nick flutter's moth design blog

entry level CFD

2012-01-24T22:47:00.000+10:00

CFD has been - and probably still is - the realm of people who know what they're doing. However recently Autodesk released a little bit of software called Vasari, which is really a software preview of some of the things that might be available in future versions of Revit. The 'wind tunnel' in Vasari is admittedly a bit crude compared to other things on the market, so you have to take the results with a grain of salt, but it does seem to give a reasonable impression of what goes on.

The thing I have been initially trying to test for ís whether the hull tramps in any particular configuration acts as sail, or otherwise increases the efficiency of the sail. This could probably come about in a couple of ways:

The wing tramps act as an end plate, and reduce the size of the vortex coming off / wrapping around the boom
The leeward tramp generates lift in a downward and to windward direction when the boat is heeled strongly to windward, acting as not very productive sail
A fixed foredeck fairing of whatever size could generate lift as long as the AOA is reduced somehow so it doesn't stall, or it is a very high stall angle section
A fixed fairing might fill the gap between the deck and the boom and increase the end plate effect, even if it is stalled.
The underwater profile of the hull generates lift

There has been mention on Facebook that there might be some legality issues with fixed aerodynamic fairings attached to the hull. I couldn't immediately see where aerodynamic fairings of this sort were ruled out, but please if you want to comment do so, I want to open up the discussion.

a couple of screen vids showing the airflow over different tramps, all other things remaining equal:

An early hypothesis is that the vortex trailing off the tramp actually seems to counteract the one from the bottom of the sail slightly. When you have a full tramp, that vortex seems to work better than with a small tramp. Just an early theory though.

gh

2012-01-24T22:39:00.000+10:00

For those who aren't all over it yet, grasshopper is a plugin for Rhino that allows you to build 3d models parametrically. You can choose to model the normal way and just let grasshopper calculate the surfaces, or draw every component from scratch in grasshopper. By using number sliders for certain dimensions, you can create fully adjustable 3d models that you can easily change and optimize after finishing the model.

In my experience this type of modelling is normally used to make things like this:

But that said, I know people use tools like Catia and Generative Components in all sorts of industrial and product design fields. So parametric models are probably being used to make boats. In fact, I'd say that if you are trying to design a boat and not using a generative 3d model, then you're doing it tough.

Here's a screen vid of one of first forays into moth design using grasshopper - the parametric wing: Apologies for the daggy commentary and vigorous cursor gestures!

back on the horse

2011-11-04T22:42:00.000+10:00

Its been about 10 months since the worlds. A pretty good amount of time to rest, digest new information, work on other things etc etc. But, the itch to go sailing is back and I now have a Doink-built Alpha shell (thanks mate!) sitting in the garage waiting to get turned into a new boat.

So, the plan was to start with the most outrageous contraption possible, and gradually change it into something that sort of worked. I'm not sure about that plan anymore, due to day to day time constraints and the pressures of modern life and whatever else. So, I've decided to go with something more conventional. Evolutionary rather than revolutionary, and maybe then try and put a wing on it.

But, it seems like a waste to just chuck ideas away, so I decided to post some things I've been thinking about on here, maybe generate a bit of discussion and possibly inspire someone else to take it a step or two further. They might trickle in, but here's the first one.

The canting foil.
After an initial thought experiment and then some basic 2d cad "calculations," I decided that this would probably be worth a try. But a discussing it with Nick and Markla, we came to the conclusion that it was going to be a lot of work and structural compromise for no a huge gain. Markla did a few proper numbers to illustrate this point. Anyway, I'm still not completely discouraged and it will just go on the back burner I think!

The system I arrived at to make this work is as follows: The foil cants side to side about a bearing mounted at deck level. Very important to have the bearing on the deck, as you seem to get absolutely no advantage over a fixed foil with it at the keel. The bearing needs to be pretty snug, so there are replaceable nylon inserts inside the carbon tube. The centreboard case is supported from the top, but a sliding 'car' that runs along a bit of aluminium bike rim acts as a third point in case you hit a sand bank. I was initially thinking of using a stainless lead screw to control the cant, but decided there was too much machining involved, so I went for an 8:1 purchase system running through laminated-in thimbles. The purchase would need a serious amount of pre-tension in the form of a big bungee to compensate for the changes in line length between 'centred' and 'canted'. Even so, you would never achieve the stiffness from the foil that you get from a fixed centreboard case. That's probably the biggest trade-off. Another issue is that you're left with a large hole in the bottom of the boat, which is among other things a structural problem. This is overcome by some longditudinal bulkheads that tie the fore and aft bearings into the chines and act as beams to stop the hull from snapping. A laterally sliding carbon plate, flexible in one direction only, sits around the base of the foil and fits into a specially moulded carbon groove at the front and back of the hole (not modeled, quite difficult to draw actually) and a small fixed venturi drains it.

In the end, the foil can cant through about 15 degrees comfortably, which is all you would need. From a sailing point of view, i envisaged that the controls would be quite lightly loaded and accurately adjustable. You would probably just centre it in the tacks and when sailing downwind. its an upwind device really.

interview

2011-02-16T19:30:00.002+10:00

Finally got around to watching my interview from the worlds. Knowing full well that i'm a pretty rough looking bloke I was putting off watching at it in the name of self esteem, but now I've seen it and i think the worlds media team really did a great job so i thought I should share it. The particular 'some guy' mentioned I think was Bill Olsen (with probably the nicest paint in the fleet) - don't think we'd met at that stage.

cheers

Belmont

2011-01-23T13:08:00.007+10:00

thanks very much to Thierry Martinez for the shot. www.thmartinez.com

Without going into too much detail, I had a great time at Belmont. It was especially good to meet so many moth people for the first time. Thanks to John Harris and Clive Watts for helping me get set up with a rig that worked, and cheers to the guys like Andrew Stevo, Bruce Gault, Bill Olsen and Al Goddard who generally hung around the repair shed and were really generous with their advice and bits of carbon. It was also cool to meet Dave Lister and check out some of his genius carbon work on the 'monstro' and likewise Luka with the scalpel and John Ilett with his latest prowler. All three are lovely looking boats with great ideas and top blokes behind them.

So anyway I didnt do very well on paper - 34th in the silver fleet and I think over the regatta i had as many DNFs and i had places. In one race i did manage a 15th in silver, which I was quite happy about in breeze. Also i logged a new top speed on the speed puck of 27.2 knots. I was really pleased, but I heard later that the fast guys average that on a downwind, so again i need to find another gear.

The boat performed reasonably. I cant say I had it right on its game because I was stuffing around with the foil angle of attack the whole regatta, and never quite got it right. I noticed after the first day's racing that my boat was sailing around with the flap fully down, which cant be fast. The refinement process was complicated when I snapped the strut in one very windy race, after the gudgeons on the gantry came apart and the rudder parted company. I could say I was a victim of the weed clumps, but the reality is that I needed a carbon spar in the strut. On Bruce's advice I hollowed it all out and glued a stack of carbon rods in the break, then scarfed the laminate back over it and she's probably stronger and stiffer now than before.

for reference, A good angle of attack for my main foil design is 2.0 - 2.5 degrees from what I have seen and what people suggest.

I got more DNFs for other stupid things - my vang strop came undone at one point and I had to sail in to fix it. The sail got chafed on the concrete and wore through the webbing strap at the top, causing it to fall down the mast and I lost 3 races I think. Angus had a similar issue and we were both at the sailmakers on the same day. Probably the dumbest was when I went out after racing was cancelled in a gusty 25 - 30knots, and blew up the vang, causing the sidestay to get overloaded and rip the front wingbar off the boat. the rescue was a bit difficult and I felt a bit bad for going out and causing drama when I should have stayed on shore. the wingbar will be sleeved together in good time, but after that I called it a regatta. It was actually pretty fun sitting in the club on the last day watching the racing. probably the best spectator sailing ive ever seen - and ive watched a lot of match and team racing!

So as a way of capping off this post, heres a diagram of something I was keeping a bit secret. Its my integrated hinge concept. It has never worked in the past, but I fixed it I think. It survived the nationals and worlds anyway. The trick is to make the centre 70mm or so a standard sikaflex hinge like a bladerider, and then have a couple of narrow points, about 5mm wide (section a) along the span to stop the hinge going 's shaped'. section b shows the normal 10mm gap to allow the carbon surface to bend around a decent radius. A few people mentioned that it might work better if the seamless surface was on the bottom, which is fine, as long as you keep the hinge dead straight so it wont bind up.

foil progress

2010-12-03T18:09:00.004+10:00

finally had some racing this week. I've been waiting to see if there was some video that I could scavenge from the pretty decent Sail Brisbane media coverage, but despite having a camera gaffa-taped to my boat I don't feature anywhere except for some brief moments. Always a bit apprehensive watching videos of yourself - its hard to know whether you're going to look like an uncoordinated fool or not. i reckon a bit of column A and a bit of B.

Aside, the foils are going well and both the boat and my technique are improving. Had a top speed of 22.7 in a predominately light to moderate-air and choppy regatta. Still that's the fastest the boat has gone, although I reckon there's a lot left in it. I never really felt like i had it wound up. Anyway hopefully with a new rig and some tweaks here and there I should get away without too much embarrassment at Belmont.

Still cant get the height control perfect through the chop, although i was pleased to see everyone else having occasional problems as well! People keep telling my that my boat goes up and down more than the others, and I'm not entirely sure what to put this down to. Sure the waves are a factor, by why do the affect me more than others? I'm putting a kink and my wand to try and space it further forward of the foil and we'll see what that does. I know the bowsprit is an option but i quite like the bow as it is. Also a lower profile boom will allow the mast to come back further while still giving me enough space to get through the tacks. more rake may help.

I put limiters on the flap down and flap up because I found that too much movement was causing a bit of cavitation around the flap that I could actually hear from on the boat. I suggest to anyone looking at building the foils that they do this too. Mainly down- 15 degrees is too much deflection. I'm not sure what its set at now, but email me if you're interested and ill measure it.

Also worthy of note, the ride height lever was really helping my takeoff. I worked out that i can neutralise the flap, reach off and get the boat speed and apparent wind up then gradually pull the ride height on, and the boat takes off much more easily than it otherwise would have. at the risk of losing what may be a slight edge, i reckon the same technique will work with a dial on your mach 2, prowler assassin or whatever you happen to bring to the potentially marginal foiling conditions at the worlds.

a couple of photos courtesy of the AYF media people, (http://www.saildownunder.org.au/) who by the way were tops.

So, reckon I should try and paint the boat before the worlds or is it fine as it is? I'm tending toward no, but I could be swayed. I think the rust stains particularly add charm.

simple harmonic motion

2010-10-24T22:02:00.002+10:00

so no results from the foil testing as yet because i cracked the bottom rudder gudgeon before the first race. sometimes when you say 'that probably wont be strong enough' its a bad idea to convince yourself that it will be. anyway its glued back together and tomorrow it will be beefed up and i should make it on the water later in the week.

The reason I loaded up the rudder and snapped the gudgeon was because of the annoying downwind motion the boat exhibits through our short chop. I drew a diagram to help myself understand what was going on- my theory is that the wave motion is wildly changing the angle of attack on the foil as it goes through the water. This can be up to around + - 5 degrees or more, depending on the boat speed and ride height. The boat tries to follow the wave- up the back and down the face - but there is a bit of lag because of Newton. The flap also complicates things a bit because it is reacting to the lag and not the wave.

The calcs suggest the best thing to do is go faster. The more waves per minute you go through, the less time F=ma has to crash the boat. But the faster you go, the greater the lift from that extra AOA and F becomes a bit more significant. also, there will be a sort of no go zone, where dead square is ok, beam reach is ok, and somewhere in between the effective wavelength gets in a problematic range and causes this kind of crap behavior. Probably people who can sail will be saying 'duh' but this has been hurting me for ages!

I still don't get why 2 boats with very similar setups will respond differently to this. Ncik said its all in the shock chord...

PDF here

more tinkering less sailing

2010-10-22T14:04:00.005+10:00

I think the 'hours tinkering to hours sailing ratio' this year is about 278:6. Not doing my boat-handling any good at all. I've been thinking i should really just outsource the sailing part and focus all my energy on stuffing around in the shed. Anyway although I'm still not landing most of my maneuvers, my work with CNC and carbon is getting better and I've been busy applying the stuf I learnt building the moth to other products.

Anyway here are a few pics of my (almost) finished set of foils. They've been out a few times now and i think they could be on the pace. not that I can judge, of course, because no-one ever comes sailing with me! Thats probably my fault for having the boat in bits every time theres a race on and going out mainly on Tuesday mornings.. mm. The 3D model of the foils is available for download permanently on the right hand side of the page. Ill get back on here with an actual review when I've had a chance to line up against someone.

The top of this has become a bit of a mess. It functions, without any reference to form whatsoever. I like it.

I also chucked a set of spreaders together. So far they work. And they weighed in 300g lighter than my old ones.

Finally, has anyone got a carbon boom they want to sell? My alloy boom is nearly dead, (ugh, corrosion) and probably adds about a kilo or more onto the boat! Luka mentioned there may be Mach 2 owners who have upgraded to CST HM gear and have no use for their flexy Mach 2 boom. Anyway I reckon even the worst carbon boom will vastly improve my boat, so please let me know if you know of anything.

Right, now for some sailing.

first sail

2010-03-28T18:47:00.003+10:00

fist go in a moth for quite a while! needless to say i was a pro and not rusty at all... anyway there wasn't too much skill required, it was just a quick check of the boat to make sure everything was going together well. It was 8-10 knots so perfect for a first go.

almost everything worked and didn't break. even though i hardly sanded the foil and there were pin-holes all through it, the boat lifted off pretty early. you could feel the skin friction so with a bit of bog and paint i reckon it will go well. much, much better already than the last foil. about half the weight too. the second attempt at the horizontal came out lighter again. the sikaflex hinge let go though. i hit the bottom once, and i think the tip got ripped off a bit and after that it started to separate. does anyone know exactly which Sikaflex you're supposed to use? i just used whatever one i had that was open. i might try a hidden hinge system of some sort, even if it means i have to make a new flap.

the 'dial' thing works well. i was a bit skeptical but the lever and rope that i have going is really effective in controlling the ride height. basically the wand pivot fitting is upside down so everything is in tension, and then the lever just slightly adjusts the length of the rope between the wand and bell crank. i have a slight problem with rope stretch/spring, but i think that will improve with use and you can compensate for it with the system.

the wand pivot is strong and declared good. basically its a Harken ball-bearing sheave stolen from an old block glassed into the hull. i modified it a bit so by tensioning the bolt you control the friction/slop on the sheave and hopefully find the happy medium. very direct, straight and very low friction under load.

the AOA adjuster on the centreboard works well except as it it you cant adjust it when the board's in the boat, because of the centreboard case prongs. bit of crap management but ill sort that out. eventually i think it will have a dial too or some other way of moving it on the water.

the weird kingpost i made seems fine but not yet tested in breeze. the cleat attachments are interesting and they seem to work. i did that because i couldn't fit them on otherwise, without buying new cleats. and the small stainless ones were like $80 each. the vang retainer is good as well - i got the angles right so the vang doesn't tighten up as you ease sheet, like it used to. wave peircing bow also a tick - i have the same freeboard as the assassin but heaps more volume because the old girl is a lot fatter, so the boat sits higher in the water and sails quite well lowriding. the water sheds well off the peaked foredeck. i reckon a proper wave piercer with no compression strut is definitely on the cards at some stage. i think it has legs. i dont actually mind the fatter hull when i think about it, because it will keep the freeboard down and thats less windage. i think i could cut another 50mm off the freeboard and 50mm off the rocker of this boat.

the gantry is shit but hasnt broken yet. the product of a vacuum bag that got a hole in it. i chucked it on anyway, but i think ill do something different. i really like the assassin gantry, might do something like that.

the flat wingbars also work. in fact the boat is noticeably easier to sail as a lowrider, really nice to sail as a foiler and much cooler looking. the little wings are good - i cant imagine they need to be bigger, actually could be smaller again.

the rudder is the final thing. i designed one already for Sam Schneider's SR71 foiler. it looks about right, at some point ill scale it back down and pull some moulds off it. i'll make the rudder foil available for download from the blog too at some point.

so im going overseas now, so the boat will be mothballed for a while. but its all set up for some serious tuning when i get back! really pleased i got it sailing before i left.

this is a good way to do the moulds if you're going to cnc it. helps to keep everything straight because the MDF is so crap with heat. that said, id minimise the use of MDF because it shrunk fairly considerably in the oven. no big deal as long as you let the foil cure before you heat it, as i did because i accidentally didn't turn the oven on! the first time round i used chip board glued to MDF, so the mould surface was still in the MDF but the whole thing had a 18mm chip board backing, and that didn't shrink as much.

below is a comparison of my foil and the assassin foil. area is pretty similar.

hull

2010-03-22T12:11:00.003+10:00

Finally the hull is faired and undercoated. wings are re-built, new foil is curing. tramps are re-done. lots of fiddly jobs but the boat is looking a lot closer to hitting the water. Im optimistic as always - we'll see if we can go for a sail this weekend. its not getting a top coat because i cant be bothered fairing the hull right now. done enough sanding lately.

I think the renovation has shaved about 7.5 or 8 kilos off the boat - hull down to 12.5 or so, lost 0.5kg from the wings too at least. anyway it looks strong enough, looks good enough. hope it works.

files

2010-02-03T22:18:00.002+10:00

having actually bought some web space the other day, i can now host big files! here are a few rhino files that i've promised in the past:

ill get back to you on the progress of the boat! briefly, the hull is done aside from bog, sand paint, wingbar joints to go (they suck!), gantry is done but needs a bake, foil is not CNC-d yet and I still have to afford the materials for it.

new foil

2010-01-18T12:28:00.003+10:00

I re-designed the foil with a bigger bulb, so that the socket could be 25mm deep. The bulb looks a bit fat, but in theory it should work. I wish I could use CFD to sort this out propperly, but bloody ANSYS are too on top of their licensing.

anyway that can get cut out tomorrow, if anyone has any comments about the shape please let me know before then!

deck goes on tonight hopefully. making pretty good ground, a good 1/3rd of the list is ticked off.

finished!

2010-01-13T23:23:00.002+10:00

well, practically. i stuck the wingbars on with string.

stood back and admired my work. (you'll notice that i stuck them on once before, made holes in the hull, then decided they were too far forward and moved them back. not like me to be that conservative, but i realised that i got my numbers wrong, upon measuring a Mach 2, and i probably should have put the centreboard case about 85mm further forward. im happy with how its sitting now. mast step is 985 from the bow, front of centreboard is 1585.) anyway, standing there planning how i was going to paint it, i realised there were still a few jobs to do. made a list.

The list nearly fitted on the foil alignment template, so thats a good sign. i reckon if i tick a few of these jobs off each day i should be done in like 3 or 4 weeks. start work in a week.

bits

2010-01-07T17:02:00.005+10:00

Foils and deck done. the laminates came up really nice. the araldite 3600 resin that Ive been using becomes so high modulus when you bake it (80 - 100 deg) that you'd almost say its prepreg. Foil came out at 1.8 kg and the deck at about the same, with a further 250 grams for the bulkheads. so the vacuum did the trick. The only problem is that the socket in the foil looks a bit too shallow, (by like 10mm, massively too shallow!) so if thats the case i might re-do just the horizontal with a much bigger bulb, and cut the tab on the strut a bit longer. Will try and make what ive got work first. I put 2 tubes down the strut this time, in case i want to do a swept horizontal with a split flap at some point. I really should have put some high build primer down in the mould first, as Andrew at CG composites suggested, because im going to have to go over everything with some black bog to patch up all the tiny holes in the weave that the vacuum leaves behind.

Anyway lots to do, tomorrow the bulkheads go in and I need to make some little angles so that the deck can stick to something. I really have no idea how people would normally stick a deck on a moth. If anyone has a suggestion let me know! also the gantry mould is ready for the CNC machine to cut out. opted for a box gantry over tubes because then I could avoid buying tube, and use the materials I have already that are leftover from the deck. quite like the design of it though so it should be fine. function over form!

ps. if anyone would like some free moth bits, i have some now redundant lowriding foils, need some care admittedly, some moulds for a NACA 66014 strut and an old repaired carbon strut that is about 1.3m long. and my old gantry.

foils

2009-12-22T18:52:00.004+10:00

finally something tangible! part 1 of the conversion is the new main foil. i figured it would be simpler to start with that and then build the boat around it. i can also get the centreboard case and the deck going when i get off my ass. i've pretty much bought all the materials.

heres the process:

The foil is longer than the last one, and the strut tapers. the hydrofoil is a higher lift section with a larger flap, as i found by doing this that the lift/drag ratio was generally better in that configuration because of the reduced area needed for takeoff. Top speed may suffer, we'll see. Also maxed out the span as much as i thought i could structurally with standard modulus carbon and wet layup (span is 1050mm). The flap is designed so that the deflection at the tips is limited to 5 or so degrees, and hopefully that should decrease induced drag when the flap is fully deflected up or down without affecting lift too much. I found that even though the tips twist down slightly, it is difficult to keep the lift distribution fairly elliptical when the flap is allowed to operate through its full range at the tip.

anyway, will lay up some bits when i get time. might have to wait till the new year.

whisper

2009-11-30T22:04:00.004+10:00

Just did some cunning measuring on the whisper boat. Looked to me like the mast was a bit forward and so was the foil. and the wings. I was thinking the same thing so i thought id check the actual numbers, out of interest of course!

I think im going to have the mast at like 850 and the foil at 1500. Keeps about the same proportion, with a bit more bow sticking out, but then ill have a gantry too. Ill have to move the wings forward because they're connected to the bloody sidestays. what an awesome idea to get rid of them! Also the rake adjustment on the fly is a step forward, with the spherical mast bearing. And come to think of it, I like that a ply and glass hull can be 6kg and $700.

Cant wait to see how this boat goes in Perth.

Half-meanie!

2009-11-18T17:33:00.005+10:00

Finished architecture on Monday, just sobered up with no intention of even trying to remember what happened yesterday and the day before. back to the blog! And before you ask, no. my sailing and my boat, sail, and attitude toward training are the main things that are slowing me down at the moment, not the blog. its not like im shaving the last couple of percent off my top speed or anything anyway.

speaking of shaving, i shaved more than 10kg off my boat this morning. this is what I had in mind thew whole time:

http://www.youtube.com/watch?v=A9AvhDm7rI8

So the hull was 19kg. ha your all laughing but i dont have any money. Now the glass shell is just over 8kg, and ill chuck a flat carbon deck on it and a couple of new bulkheads which might take it up to something like 13 or 14. Seriously the foredeck was about 4kg, the mast base was 4kg. and the deck was wrecked. The skin is not in great condition with a bit of osmosis and whatever, but it'll have to do for now. It looks overbuilt anyway, so thats a bit of a plus.

This is definitely the way to build boats though! well so far its been more like destroying one but its pretty much the most fun you can have. especially when you're trying to take your mind off a cracker hangover. There are so many good second hand boats out there that are a bit too big nowdays, getting an old prowler and doing this might even work out cheaper than building from scratch. and you'd get good foils, a rig etc. and you can use your own ideas.

So the Flashheart idea looks to be out the window. Boat 2 (yes im optimistically thinking about a year ahead) might be a big mod of a light, pre-preg well built boat. So much less work. Time on the water mate!

Also, obviously I didnt sell the boat. It is still for sale, though I probably might want to hold off until the mods are done and Ive completed at least 1 race!

Alright, gotta go get drunk again. more later.

CNC

2009-08-18T21:00:00.005+10:00

so heres what ive been doing lately.

http://www.youtube.com/watch?v=LKyu_ECy8rg

designed it in rhino, built it from the cheapest bits I could find, and very suprisingly it seems to work! Got a kit with the electronics and everything from http://www.oceancontrols.com.au/ to power it. Its cutting area should (i say should because i havent actually tested this) be around 1210 X 2440 X 300mm. So a whole moth mould will still be in a couple of bits, but it will cut out a whole set of foil moulds from one bit of MDF. cant see why it wont cut solid fibreglass or solid carbon in the future either. We're thinking of using it to do some ply stuf for joinery and that kind of thing as well, and of course the last couple of models i have to do for my architecture degree.

anyway im theoretically set up to be a moth home-builder now. you seem to need one of these things if youre going to even have a chance at building a good boat these days, foils etc, so we'll see what happens. heres an image of my test file in wood. Below it is the toolpath.

As always the rhino file for the machine is available if anyone wants it to inform their own design. im not going to go so far as to recommend it just yet!

for sale

2009-05-23T11:45:00.005+10:00

ive decided its time to sell the moth to get some cash together for the new boat.

also i probably wont get much time to sail it while building the new one, its about as fast as it will ever be anyway, and tinkering with an old boat distracts you from doing work on a new boat.

so if anyone is interested, it comes with:

home built foils that have had 30 or so sails and plenty of crashes, with no structural repairs, still in good condition except maybe the main flap hinge but i think ill fix that before selling the boat
adjustable wand that still needs some tweaking, but fundamentally works well
lowriding centreboard and rudder that still fit (rudder needs gudgeons)
road trailer, built for the boat, ok condition, painted not galv.
ka sail, standard bladerider one, been used about 20 times total. still in good condition
burville mast (bladerider) with the top section repaired, but going fine and sail sets exactly as before, used 10 times, so like new.
alloy boom, near new ropes and blocks

generally the hull, wings and traps are starting to get a bit tired, the boat leaks a bit etc. and its by no means pretty. at this point i might as well admit that it could use a coat of paint.

that said its been my faithful steed over the last 3 years, ive learnt stacks sailing this boat and though not that compeditive at any point, its been a great introduction to moths for me. the hull is a bit heavy and thus bulletproof, and thats been a pretty important thing. the boat has finally progressed past the point of breaking something every time you go sailing, so everything is strong enough now by a long process of trial and error. With the current setup, although you cant go upwind at the same angles as well.. sabots.. you can still match the slower skiffs around the course, losing on the upwinds and gaining on the downwinds. also it takes off with my 75 kilos in like 8 knots, not 6 or 5 like good boats with light people. mainly due to the extra weight and the increased drag from the square foils.

so its a bit of a sad day, anyway ive put $4500 on it, thats gotta be about the cheapest foiling moth with flaps and wands and stuf. ever. for that price its a good toy or a relatively cheap first moth to learn foiling on and get on the water. you can work out pretty well from my old posts whats there and its condition, so otherwise make me an offer. remember im a starving, barely employed uni student.

wingtips

2009-02-21T19:19:00.004+10:00

Ok so i have been slack. I still dont even have a mould for the new hull or even a block or foam. absolutely no progress there. the 3d file is router-ready but thats about it. Had a few projects that took over and now that theyre done im back at uni and so progress i fear will be slow.

anyway ive been still tinkering with the blue boat - broke the gantry and it was off the water for a while and now its fixed back up again, a truly crap repair job later. one of the things i did was redistribute some area between the foils, just for the sake of an experiment. so i cut 100mm off the rudder span and added that to the centreboard, in the form of these wingtips.

Everyone i talk to says "wingtips are tricky, you need to do 3d analysis and work out the nature of the vortex at the design speeds etc." Anyway i pretty much ignored the advice of everone who knew what they were talking about and just designed some in rhino that looked good, cut them out, took a mould etc. I think they came up pretty good, the foil sections are pretty accurate at least. and they seem to work too, subject to a bit more testing, two things have happened; the boat launches much better and at lower speeds, and the hum that i used to have is gone. also there is no noticeable loss in stability from a smaller rudder (550 span i think) and it all feels smoother, and the boat want to go straighter. i could be kidding myself about that last bit. foiling manoeuvres were easier. also i have a new wand which i reckon is my best one so far, with a paddle about 200mm from a very flexy tip. If i do anything else i may want to extend the flap onto the wingtip, i dont seem to have quite as much response.

anyway heres a pic of my wingtip, if anyone wants one for their old and shit square foil let me know and ill make you a pair of blanks, im keen for another opinion. chord is like 115mm or so.

done

2009-01-10T18:24:00.006+10:00

So the aussie flasheart design is done... sort of. feel free to email me if you would like the rhino file. note the bridle attachment point. i think its cool. wand mechnism: grearing is adjustable by a thumb screw. the front bung goes in above the pushrod exit point, under the cover.I thought of a neat way of adjusting the rake of the centreboard too, which is basically a stevo top rudder gudgeon for the centreboard, that the retainer pin goes through. a thumb screw at the front of the centreboard, just above the deck, pushes a rod back and forth inside the top of the foil and the pin goes through that. the rod would be like 50mm long and is held in there pretty well so the hole in the carbon can be elongated. it means your centreboard case needs to taper slightly, but the range of adjustment is no more than 1 or 2 degrees to accommodate all wind conditions.. just a thought. i think ill be doing that if i build another foil.

also had a glamour sail in 12-15 kts and pretty flat water at RQ, took my iphone with recently updated gps software and for the first time i could download my track. the data was pretty noisy, but i used excel to average it out and im pretty sure i hit about 20.5kts, my best average over 100m was 18.1. i was doing about 12.5 - 13 upwind, but not pointing very high at all. I might try again one day with a real gps. it really didnt feel that fast, and i think the boat has gone faster so ill keep pushing it.

^ i entered the seabreeze.com.au competition. i couldnt help myslef, the prize is pretty amazing. i reckon the dude with his hair on fire is a definite winner but.

fixed the mast, sort of. have been sailing without using too much vang or cunningham, and because it has two sleeves in it now its pretty much the stiffest topmast ever. so i dont really get a good leach anymore and hence the no pointing. im getting a new one.. just as soon as i go to work, earn some money and get paid, subtract bills and living expenses. i think i logged 6 hours this week so im not looking good.

finacial situation doesnt look good for a speedy build either, i might have to find a sponsor. though i am in brisbane, going to uni full time, its all a bit hard. anyway at least that gives me time to go over in my head the procedures and simplify it right down.

anyway thats about all, best of luck everyone at the nationals, hope you dont break anything, forget what hole it was in etc, hope your knots all stay tied up, and that the breeze is between 8 and 20kts the whole time and that the chop is less than 2 foot!

hand luggage

2008-12-16T13:44:00.002+10:00

heres a concept, maybe for the mach 3: a moth that fits in a suitcase! or better still hand luggage. they have fishing rods that do it.

step 1: cut your mast/hull/wings up into little pieces
step 2: place in luggage
step 3: reassemble at desired glabal destination.*

*nick flutter takes no responsibility for any complications arrising from above process

2008-12-16T12:07:00.004+10:00

Just a few more images of the specific failures. you can see that the pocket was clean, no sand, dirt or grit. the sail has been rigged up pretty much exclusively on this lawn the last 10 times. and the condition of the mast is, well, brand new.

1 hour sailing, 3 hours commuting, 2 masts and 1 drunk dude with a broken spirit.

2008-12-13T17:23:00.004+10:00

The photos say it all really. 2 out of 3 attempts to go for a sail have had me in my gear, getting ready to lift the boat in the water and this. First my old mast, below the hounds, so i put it down to age or cracks or something. Today's victim was a bladerider mast that had been used twice. im not sure why its happening - maybe i had too much vang on or something when the boat was leaning over. but it was well and truly eased from where id have it sailing, like at 30%. same with cunningham, at say 40%. maybe my spreaders are keeping the bottom section too straight. but how do you tell that? there was about 50mm of 'kink' in the forestay after the mast broke, no idea what it had before. maybe my rig tension was too much, but i doubt it. maybe i crushed it last time i sailed in like 20 - 25kts, maybe a manufacturing flaw (but the new one broke in 2 places) maybe i broke it when i cranked the cunningham while rigging , boat upright, to see how flat i could get the sail for the windy day. but i have 2 less purchases on that than lots of people, and i didnt go past the red line on the mast. maybe its because this mast was different to the standard ones, apparently having a stiffer top section, and that stiff section couldnt take the bend that i put on it with the long front prodder. but then why did the last one break that the spreaders were designed for? surely there is more load when your out sailing...

anyway id be interested to know if anyone has seen this before, and whether, when you rest the boat on the mast, there is a common law that you let the control lines completely go.

to top it off i got yelled at (and told to fuck off) by some RQYS voulenteer with 3 missing teeth, who was at me to move my car when i was packing away the broken bits in despair. a great day in sunny queensland.

2008-11-16T23:20:00.004+10:00

the next iteration:

bow higher, aft deck convex, aft wing struts... strutting, gantry (not fully thought through) more kingpost rake to resist max loads (12 deg), decision made not to slope the transom because i couldnt get it to look cool (tiny transom anyway, might revisit this) tramp not updated re. filling holes slightly.

Still not sure about the volume / freeboard, im inclined to thing there is too much at the mast, (450mm to top of deck) yet to measure a bladerider for comparision.

the rest of that foil article

2008-11-16T20:49:00.005+10:00

Heres the rest of that article. 80s gold.

Aso i just want to put it out there.. i have hinge damage...

Though i have yet to lose the whole thing on foreign soil, this moderately irreparable cracked hinge may be something that we will be seeing more often.

foil article

2008-11-11T18:58:00.003+10:00

heres something i just stumbled apon when flicking through a 1983 issue of Australain Sailing. may explain why some people have massive rudder ventillation issues and I dont seem to. my rudder is a 66012 as opposed to a 0012. bring back decent sailing journalism!

new stuf (hull, wings etc.)

2008-11-11T17:26:00.003+10:00

so ive been neglecting this for a while, mainly due to another architecure folio.
been sailing a few times, but mainly been in front of the computer evolving into one of those hunched, pale, widescreen-format-eyed little creatures (from the future).

anyway the whole time i was studying i was sidetracked with a stack of new ideas for a moth, and im pretty sure ill be building something over the summer "break". The lines are from Doug Culnane's Lord Flasheart, designed in collaboration with Adam May. (cheers doug, looks great)

Flasheart is available for home builders like myself to have a crack at, so in the interests of total tansparency ill be chucking everything up here form design to eventual completion. that puts the pressure on to not fuck it up i suppose.

construction will hopefully be by female mould, cut from high density foam using a 3d router. dont know how much that will cost yet, but the plan B is a hot wire and ply plug. the boat will be built in 2 halves, vacuum moulded etc etc. the aim is to keep construction extra simple and quick so that the thing isnt still half finished in a year or 2. kinda defeats the purpose. 10kg for the hull will be acceptable, but i will of course be going for lighter. as this is my first go i want to make sure it holds together.

what the wind 'sees'

there are a couple of odd ideas in this. this is only the first iteration, i might do a few versions with different configurations to get a feel for what will work best, be lightest and cheapest. I'd love some feedback on what you think will work and what wont. at this stage i think its better to get a bit of consensus on things. The main decisions i've made with this one:

Foredeck, wavepiercing bow - The stem is even shorter than Flasheart, which is on the short side as it is. im hoping that the bow in this configuration will go further underwater without digging in, and use the buoyancy around the mast base to pop back up. i find that most of my stacks at the moment are due to the drag of the foredeck, tramps and ropes stopping the boat, rather than the pitch.
Kingpost, Recessed foil wingbars - The foil shapes are mainly there to reduce fricion when the hull does go under a wave, though they should reduce windage a bit too. circles are terrible in terms of drag and im avoiding them as much as i can. The kingpost is cantillevered from the keel, so there is no need for a forward support, that adds areodynamic and hydrodynamic drag. ill make a bladder mould for the kingpost, so i can cantrol the fibre orientation and reinforcement.
Wings - Raised up and out of the way of everything. the freeboard is slightly lower than flasheart aft, (50mm) the wings are slightly higher. They are airfol shaped, only because i think it would actually reduce drag a bit. it opens up a big gap between the tramp and hull which will reduce windage.
Flare - I altered the bow of Flasheart a bit to include a 10 - 15mm deep step. for lift.
Centreboard is 100mm further forward that Doug had it - his was in the same place as my current boat, on which mast is 200mm further aft. what is a standard dimension these days from transom to front of centreboard case? assuming 8 degree strut rake.
the outside wing bar continues aft of the back wing bar. the joint is easier, and you reduce tramp area, while still having somewhere to sit. and if i find the back bar is too far forward, i dont have to buy new outer bars.
There is only one internal bulkhead at the centreboard case, which is pretty small. (divides in 2 as per rules) some diagonal reinforcing will be built into the hull laminate.

anyway the only things i am sure about at this stage are the general freeboard, and the step in the chine.. foredeck could come up, aft deck could be convex (better for 3d router). wings could atach to the hull (i feel it may be better to have something solid to stand on, rather than just tramp, though this means reinforcing the deck a bit?)

anyway ill keep plugging away, please email me if you have any ideas

2008-10-13T21:07:00.003+10:00

been out sailing a couple of times since the lake

the boat is getting better and better. the foil mods were aimed at reducing induced drag when the flap is fully deflected, and do seem to give a smoother accelleration at takeoff. the wand system is getting better fast, with my bendy bit of aluminium allowing for the whole thing to be mangled on the water. ive taken all the slack out of it and i now get that bumpy feeling when the boat is going quick upwind, and have a greater range of where i can sit.

my dodgey skin fitting rudder adjuster works a treat as well, after a bit of WD40! ive also managed to reduce a bit of friction everywhere (hello wd40 again!) and im now almost at bladerider standard in this department.

the flap hinge incorporated into the laminate has started to crack and distort, and im not sure ill do it agian. if i do, ill use something different. the problem is you cant replace it when it gets a bit shit (if this one gets worse, ill cut it off and do a sikaflex hinge)

its now obvious that the boat is too heavy, too leaky, and the foils are too square. time, it seems, for a new boat!

allboats

2008-08-25T08:48:00.003+10:00

lake cootharaba is getting a bit too shallow. the long walk out to the middle to get on is getting too long. and then you get the boat up and get on and you're sitting on the foils on the bottom, i ended up just sitting back dragging them through the mud until i was up and going, then trying pretty hard no to crash. and repeating this procedure after every tack.

aside from that the boat went well, and improved over the weekend. in 10 - 12 or more it goes fine around the course. in less than that i can foil on reaches and sometimes upwind but not really downwind, and i cant point. since the setup is getting close to good, i'm starting to blame weight, 'square foil drag' and 'fat ass hull drag'. these are things that wont be fixed with tuning, though i plan to make a few changes to minimise 'odd shaped gantry drag' and 'poor sailor finesse drag'. also im getting the pocket in the sail adjusted to my mast, which may hopefully pull some draught back in the sail to line up with my aft centreboard case. i think that may give me some more height upwind.

anyway that said i had moments of glory; like picking through a fleet of A calss and nacra 5.8 cats on a reach in 10 kts. or beating sharpies and MGs around the track in breeze, despite my shit upwinds.

on the way home some tired dude ran up the back of the trailer in traffic on the highway, doing about 20ks and we were stopped. missed the gantry (that hangs 600mm over the back of the trailer) by centimetres, broke some lights and stuf on the trailer and sheered the bolts connecting the hitch on. so while his car got put on a tow truck with some pretty severe facial modification we sat on the side of the highway wondering how we were going to get 3 M12s to get the trailer back together and get home. anyway long story short his dad rolled up to take him home, turned out he worked with my dad, (brisbane is small) so they went off on a mission to get bolts leaving me and the tired dude who'd just nearly written off my boat to make small talk for an hour on the side of the highway. fun times.

sailing

2008-08-02T20:55:00.002+10:00

went out for a sail in gusty 15 kts with Rod from the gold coast. the boat went ok, though the flap response is still not adequate despite all the improvments. i need another change of wand to a bladerider style thing with a substantial flat bit on the end, that will pull it back propperly. also the straight wand is the way to go.
had a go on Rod's bladerider, and doesn't that make it obvious that my boat is underperforming! you just sheet on, point it, it pops up to the right height and accellerates endlessly, without spontaneously launching out of the water, tipping over sideways or sinking back down. i think i hit over 20 on his velocitek, though it may have been lying. the linkages on his boat were working overtime, while mine were kinda stopped, lethargic. it was interesting to see my boat being sailed well by someone else also, and i know a couple of things. it can go quick upwind when sailed propperly, though probably not in less than 15 kts. It looks really bulky when foiling compared to all the other boats. its like the fat kid.
resolve to put it on a diet. failing that a new hull/wings.
new bladerider sail is an improvment, needs slight luff adjustment.

wand

2008-07-16T20:59:00.002+10:00

i did a couple of maths and realised that some of my light-air trouble is possibly stemming from my technique, rather than from setup problems. (would be great if it turns out this is the case.)

Basically when i sit at the back of the boat and try and launch, i can get up to about 7 degrees angle of attack on the centreboard foil as the bow lifts up, and my boat's fat ass drags in the water. lifting off like this the wand starts moving the flap up, as the front of the boat starts to clear of the surface. in this configuration, with the flap down say 5 degrees out of 20, the centreboard Cl is 1.57 and Cd is 0.0193
If on the other hand i was to sit really far forward and keep the nose buried, i could keep the flap at say 15 degrees down, at the same stage of takeoff. in this configuration the centreboard angle of attack is 0 degrees, but with the extra flap deflection im still getting a Cl of 1.54 and a Cd of 0.0156. so this is better, same lift for about 80 to 85% of the drag. ill try it out on the weekend.

also i ripped off my crappy wand. finally. i laid up some new bits tonight that will allow me to adjust everything about the wand, and to use carbon rod and tube of varying stiffness and size. I have a choice of two wands to start with - a straight stiff one with flexible tip and a kinked, stiff one like the old prowlers, with a flexible tip as well. ill try both on saturday weather permitting. The aim of all this is to keep the flap at full deflection while the bow is within a foot of the water. the winning wand gets glory. and to stay on the boat. it is possible that they will both lose, in which case shame will be brought apon their families. and they both also die.

testing

2008-07-12T18:13:00.002+10:00

went out today for a few hours to test the new modifications. conditions were like 3 to 12kts. anything above about 8 i was foiling, though probably needed 10 to go upwind and downwind propperly. everything worked well, no breakages, nothing moved at all. didn't capsize or crash, but i was playing it pretty safe. tried a foiling tack and almost threw myself off the back corner of the wing, holding onto the tramp lacing with my feet. it turns much quicker on foils!

The linkages work much better, and the rudder adjutment in particular is a massive step up from what i had. the wand vibrates when going slow, which is annoying, so ill take to it with the grinder and make it flatter on one side. also thinking about a flat surface on the end, so that not as much of it drags in the water.

i need a new sail.

im not quite happy with the angle of the centreboard. i noticed that i had the rudder trimmed back, flap up about 5 degrees, to the point where half the time it was actually pulling the transom down; you could see because the top gudgeon was touching the top of the gantry, rather than there being a small gap. seems to me the rudder foil could be smaller. before i go cutting stuf im going to make an F-box of sorts, a contraption that lets me adjust the rake fo the centreboard over about 5 degrees on the fly. also i want to put a small bulb at the T joint of the centreboard, to hide a wad of carbon uni that i will wrap around the leading edge at the T. the crack didnt get any bigger, but im not going to risk breaking this foil. so there's 2 or 3 projects to keep me busy(er).

linkages relinked

2008-07-05T22:30:00.003+10:00

just a quick note: the boat is nearly back in one bit again!

all linkages are now stainless, after much swearing at (breaking of) expensive taps/dyes. there is less slack and the ends are more robust, especially the new flap joint which is a beast. see below, pretty self explanatory. i think the bladeriders have a similar thing, with the benefit of having a nice thick bullet fairing to hide all the shit in. i reckon ill have to fair it a bit.

the main foil appears to be at a good angle to the static waterline, about +1.5 to +2 degrees; i think the flap was just jamming in the 'up' position after the linkage broke within 10 seconds of leaving the ramp, giving me that 'sucking' feeling. also theres a 10mm long crack at the t joint of the new centreboard, not sure if its superficial or not. im keeping an eye on it. be sailing soon, should be interesting.

The States

2008-04-20T18:05:00.004+10:00

Im not actually on the same lap as matt...

1. out of control approaching the bottom mark. i was on the same lap as the scows.

2. at least i missed them.

well I finised two races, and in one of them i beat another boat.

Had a couple of teething problems as you do when your that unprepared at a regatta.

Saturday was a bit of a write-off, as it was squalling through at 20-30kts as predicted. there was one boat in a fleet of 11 which did not sustain any damage, and that was Matt with his bladerider. He sailed the boat pretty damn well for the conditions. The sheer variety of damage seen on the rigging lawn after racing was abandoned was impressive even for a moth regatta. I lost my rig, and in the process busted a panel in my pretty shagged sail. (fixed with gaffa tape) The foils were fine, but they were probably to blame for the whole 'losing the rig' caper in the first place.

I have somehow managed to stuff up the angle of atack of the centreboard, i think. There isn't enough +ve angle, which meant i wasn't getting up and foiling at the kind of low speeds i should be able to. I will fix it by increasing its forward rake, which in the long run isn't a bad thing. This means i need to modify my centreboard case thing.

The rudder adjustment systems is shit. needs a better sollution.

Both ball joints failed on saturday, and though i tried to fix them with 5 minute epoxy, they were too loaded up and snapped again within minutes. So i sailed Sunday with no flaps at all, and it was predictably hard to foil and hairy once up. I have a new 'bladerider inspired' sollution, which should work or at least look a bit pro. Means ill have to go back to stainless rod for pushrods instead of fibreglass. no big deal.

Anyway, for the next month or so I've got a bit on at uni, probably not much will happen on the boat. After that ill sort out a new mast and sail, and get to work on the few things to tune before i go sailing agian.

race ready but no sail today

2008-04-18T15:29:00.002+10:00

its 30kts from the SE today. had a couple of odd jobs to do, could have dropped the boat down to the coast today and got a quick sail in but i decided it wasnt worth it. probably better to get some uni work done. Rigged it up as best as i could in the garage to make sure the flaps worked etc. they did, here are a couple of images.

Done and dusted

2008-04-17T23:34:00.002+10:00

Dusted figuratively not literally. The dust will blow off on the highway tomorrow.

Missing one tripple block on the cunningham, ill have to get that on the way. The forecast is for breeze, 20-30kts, i am dobtful whether the boat will last the weekend and more doubtful about the sail. (now largely just gaffa tape) However i haven't fixed the low-rider rudder so foiling it is, and theres no backing out. The boat is literally rough aroud the edges, and obviously underprepared, but pending the success of the ball joints on the flaps (curing now) i'd say all the systems are go. [im liking this motif of using cliches in their original context] The adjustable gantry looks pretty good, though i realised why everyone else's have only one lower strut and not two; there needs to be some flex in the joint between the strut and the bottom gudgeon to facilitate easy adjustment. anyway its fine for now, hopefully i've got the angles right and i wont need to adjust it. The cams seem to work in the sail, ill wait and see on that one as well. i have a spare just in case.

gantry done pending 12 hours @ 80deg.

2008-04-16T00:06:00.003+10:00

The release went well from the mould, by my standards. (lucky i didnt spend too much time on the mould.) The vacuum finish is impressive, the part is actually lighter than my previous gantry and 200mm longer. and intact. yay. at this point i declare the design to be good, and the construction to be good. lets see how we feel after a couple of sails...

The ball joints on the other hand were a complete failure, i tested them with a good solid yank and they came off. will swage copper ones tomorrow. also got the rudder gudgeons on. 6 jobs to go.

sucker!

2008-04-15T00:18:00.003+10:00

My $150 ebay vacuum pump came through with the goods!
im bagging everything form now on! something to bag, ill bag it. fibreglass, oranges... small animals... lock up your pets!

yeh anyway so i had a couple of small issues getting it to work, seeing as it was my first go, and the job was quite complex. i think that box was the most complex thing i've ever laid up; it had lots of different ingredients and was awkward to get your hand into. My main problem with the vacuum was in the spikiness of the mould. You wouldn’t think so hey. The spikes, nails, bits of glue/bog etc made a couple of little holes in the bag, and i tried patching them up with tackytape. Didn’t work, so i got a whole new bag (garden strength garbage bag) and put the whole mould and bag in that. Taped it up. sweet.

Carboned up the other bit of the gantry, the two tubes. Also stuck some little globs of glue in the exact right places on the control rods in the foils to serve as the balls in my flap ball joints. Got the stainless T piece welded also, thanks to Rod at Astro Metal for being a good bloke.

8 things to go on the list.

working parts

2008-04-13T23:54:00.003+10:00

tried out the vacuum today, seems to work. will have a more definitive answer tomorrow when i 'bag' the gantry.

otherwise on track to be done for thursday night hopefully for a sail on friday!

rigged up my flap adjustment systems, the rudder system is a bit questionable. not sure if i have gone forwards or backwards with that one. (the extra bits on the rudder are the remains of my old system; im not prepared to write that one off just yet.

The centreboard control mechanism needs a taller mounting block to attach the cable to the cockpit floor, and i think ill bodgey something up there cos i already have the gear to stick a rod through the boat bladerider style. just not the time. there is more friction than id like in that system but at least not too much slack.

Overall im pretty happy with the new main foil, which is now completely done sans ball joint. The top skin hinge is neat, and flexes really well, and the gap closes up completely when the flap is at full deflection. I have an issue with some .5mm lips on the top surface around the hinge, due to my not laying the kevlar up in the mould, but tacking it in later. not top priority though. if it survives one regatta i might think about fixing those.

pretty hectic day tomorrow of uni and gantry, with a few vacuum bits still to get. we'll see if i cant stuff up my schedule.

a sigh of relief for the foils are done...

2008-04-13T00:16:00.003+10:00

pretty much anyway.
a few cuts here and a few holes there, a bit of sanding.

the rudder is strengthened almost to the centreboard spec, it will hopefully be strong enough. (in its defence it is 2/3 the area... your honour.) i made it shorter beneath the boat so its foil travels 60mm above the line of the centreboard foil, and out of its downwash. there will be a reduction of the torque on the gantry from steering and foiling high, and also it will help the foil ventilate in a crash and thus not snap. we hope. and since there is not so much rudder in the water when foiling high, it will reduce my tendency to jam the tiller towards me to bear off before crashing, as that little bad habbit was breaking things... well reduce it by making it pretty much ineffective. hopefully my new reduced friction centreboard flap will help in that respect too.

Now for the gantry. The QLD moth states and my deadline are fast approaching (we're inside a week) The gantry should take 3 or 4 days to put together so i may even be able to rig the boat before the regatta. ha! as if. I bought a vacuum pump off ebay today for $160 bucks, which i think was an ok buy, and its in brisbane too so ill pick it up tomorrow, get some tacky tape on monday and be sucking on monday night. in the mean time i need a jig to get the angles of the tubes right and get them glued/carboned together.

other than that i need to fix the hole in the boat (i bought a clear bulkhead cap for it, stuck it on, but it was a tight fit so when i tested it after the sikaflex had dried, i realised it was squashed and the cap wouldnt screw in.) (try again timmy. Timmah!) I need to get my welding bloke to weld my little stainless gudgeon for the gantry lower attachment, i need to get a batten for my sail, and i need to make those fiddly little ball joints that attach the rods to the flaps.

and that is all.

Bell Cranks and linkages

2008-04-06T01:17:00.003+10:00

Knocked off a few niggling little jobs today. It's been hard to work around uni and last night was my first good sleep all week (3am - 11am). will be no such luxury tonight, this counts as procrastinating and i have a meeting at 1pm tomorrow (sunday!) and about form now till then worth of exploded axonometric diagram to do...

Anyway i got the bell cranks designed and cut out. All the linkage bits i pretty much thought up as i went along, though i had a vague idea of what i wanted; they definitely had to be bigger than before, and i wanted to minimise friction and slack as much as possible. The little carbon forks on the fibreglass rods I think were a good idea, easy to make, we will see whether they hold together or not. they look pretty tough anyway. My little stainlless threaded fork is an M5 turnbuckle body that i cut up, and took about 5 minutes to make with the grinder. The thread is done for you its great.

I also took the opportunity to finish off the cams and do the wand as well. The centreboard system is pretty done save a bit of bog and the ball joint on the flap. Im waiting until I've done the gantry before i cut the rudder to length and put its linkages together.

I checked the centreboad foil angle of attack today too (first time in the boat) and its what i wanted (good management more than anything i think!) between +1.5 and +1.8 degrees on roungh calculations. Much more than that and you start paying drag penalties, but form memory up to about that range you only gain 1% or 2% Cd but significant Cl.

Also i went to pick up the carbon tube I got from CST for the gantry from the post office as i was out when the courier rocked up (as is always the case) but the post office is apparently shut on the weekends??? wtf? how backward are we! I now get the whole '5 working days' thing. There must be an easier way to get something from one person to another... in this day and age.

It had a baby and then the baby had a baby.

2008-04-01T21:31:00.006+10:00

What i am of course referring to is what is by now one of my favourite things to do; pulling a mould of something out of the oven and then pulling some nice looking carbon bit out of the mould. and intending to wait until it is cool to open the mould but not having the patience and getting burnt. and in this case dropping half the mould on my toe.

cool. so randemnity aside, i have, for the most part, a foil. the flap works after a bit of cracking of stray bog, and the recess i made in the mould (at the T joint for the flap) came out perfectly.

The oven sat on 75-80 degrees for 24 hours, last time it was summer and it all got a bit hotter, more like a solid 80-85. and the resin loves that, so consequently i haven't got the tesnile strength in the resin quite as good. and it has a different, dull pitch when you knock it. but its still ok. that coupled with the better lay-up and a couple of other dirty tricks i have up my sleeve (rubs hands together) should hopefully make this one not break.

so also the top hinge worked well. The kevlar is 2 layers of 75g, one at 45 degrees, so its pretty much exactly as flexible/stiff as it needs to be. as you can see the gap closes up pretty much prefectly when its fully deflected, which will be fine, as id say it will create turbulant bubble at the kink and be pretty efficient. with the flap up at high speed the separation point on the bottom surface is well forward of the gap, so no real drag there either I imagine. Thats my (probably ill informed) justification anyway. wait and see.

sandwiched

2008-03-31T00:03:00.003+10:00

laid up all the carbon on friday, laminated the 3 bits together today. went fine, im happy with the amount of material, though this time i didn't reinforce the skin so much at the exit point and at the T-Joint. There was still ample weight of carbon in those areas but, the weakness last time was in how i dealt with the shear loadings.

Anyway i've improved the sheer resistance in a couple of ways, the result of which will hopefully be a long as prosporous, successful life for the foil: (carreer as a banker, hot wife and a couple of kids, townhouse in central sydney, big boat etc.)

First of all the T joint has no foam in it at all, just glue (sp microfibres). Last time it was foam and bog (Q-cells) with carbon strands in it, that wasnt enough.

There is some diagonal carbon along the front and back inside edges in the areas of high shear stress - i just chuked it in there with a big glob of glue in the middle; the idea is that when the mould squeezes together it gets pushed to the places the glue is oozing out.

you can see in the photo I integrated my carbon T-piece into the bottom surface, that pushed straight up into the foil and is encased in glue. hopefully there is no way in the world it will separate from the bottom skin, or pull out of the strut.

Lastly i plan to further tie the leading and trailng edges of the foil together around the T joint area and the exit area by making carbon 'wet bolts', at about 30-50mm centres for about 250 - 300mm, to join the top and bottom surfaces. ill put photos of them up when i do them.

Also i cut my finger twice in the same spot with the grinder. first time with the cutting disk then again with a sandpaper disk. the second time it went straight through my nice fresh band-aid. I put a heavy glove on after that. When you wear a glove you might as well have a bit of wood for a hand.

waxed and ready

2008-03-28T00:03:00.004+10:00

I think this is turning into a way for me to summarise my days work, so i can swich off and so it doesnt keep me up half the night planning anf recapping. and mistyping.

anyway i thought id get the foil laid up today, but kinda ran out of time and oomph.

made a last minute alteration to the mould; something id been planning to do but forgot about. its made out of some thin acrylic filled with araldite/Q-cells, took 5 minutes to set. stoked. i wanted it to be quick as at that point i still thought id be putting some carbon down over it tonight.

Its there to create the gap between the foil and the flap, so i dont have to cut a gap and thus stuf up the carbon skin. also last time i had to reinforce the centre of the flap from the outside after id made the cut, this time i can do it from the inside and it will all be flush. saved some time. its a bit rough cos i didnt sand it at all, just chucked wax straight on, but itll do. may have to bog the foil slightly (probably will anyway, as the fibres wont want to bend around, and i dont have a vacuum set up yet.)

Came to the realisation that i should have wet out the flap hinge in position in the mould, and stuck the plastic spacer strip on it there too. now i have to glue it in with PVA, and glue the spacer onto it. hopefully the mould type PVA will stick it. I wasnt organised yesterday to do that, so it never would have happened, but for next time...

Also completed step 2 of the cams, ill see how they come out tomorrow. ill bake them with the foil so ill post a photo of the finished product. i think they will be ok.

The carbon is now cut out too. its such a shame to cut up those big perfect sheets, but you gotta grit your teeth and do it. and hope you get it right. the hull became a pretty good bench, at 21kg bare, i think it is almost better as a bench than as a hull. anyway thats a couple of projects down the track. Oh also i cut a hole in the hull that i really shouldnt have cut... more on that later.

Finally i just want put it out there and say thanks to Andrew and Scott at CG composites for being so helpful with the resin and reinforcements, bog, glue, and peel ply etc. and to Mel and Miller and David at Glascraft Marine for putting up with my crap. From those two places i've been able to get 90% of the materials I need to keep this project going, and some good sound (and patient) advice, which has probably been the diference between a semi success (so far) and a complete cock-up. also Bretts/Bunnings you're both wankers, though 'Tube Sales' at Yatala i like.

gantry mould, cams, foil prep

2008-03-26T19:29:00.004+10:00

Unrolled the sail today and noticed that its not only completely shagged, but i was missing 4 out of 5 cams. i think i gave them to emo in return for partly busting his sail. so anyway i've half finished a new set of 5 out of carbon, i dont think there will be any weight saved rather its just easier than finding where to buy them. when theyre done ill decide whether theyre good or not. i hope they dont snap in a race. just one more thing to go wrong.

also laid up the T piece to tie the bottom plate of the foil into the T joint, and also the tang to attach the gantry to the transom (in the same mould.) mould looked cool i took a photo. The T piece i will drill some holes in, to make sure it bonds well to the bottom plate, also i will put a couple of layers of carbon over the top of it.

Did the hinge as well, had an interesting incident with the leftovers of my hardener-heavy resin (to make it a bit more flexible than normal) started smoking and actually boiled and set in the tin at the same time. must have been hot today.

construction commences!

2008-03-22T15:40:00.005+10:00

about a year late... but hey. what can you do.

hopefully it will all be done in time for the states on the 19th of april. if the new foil's maiden voyage is race 1 then i guess that constitues success. !.

The foil is designed with some sneaky new improvements, and i have re-surfaced the moulds (they are a fraction more accurate to the NACA shape now) and added and subtracted aluminim strips as appropriate. The front edge of the foil is now 10mm forward of the strut, so that the rod has more leverage on the flap. I've stuck the moulds back together like before, so that all the angles are adjustable, using longer bolts this time, and the result resembles some kind of fusion beween a smoked chedder and a jarlsberg. lots of crumbly holes. whatever, they'll get covered in wax and resin anyway.

I've also designed a new gantry, maxed out to 500mm, as the spacing between my foils is, well, close, due to the limitations of working with an existing boat. Ill make a good mould for this so that sometime down the track, if need be, i can make a good, light version with my vacuum gear that im going to buy when i get cash. Although if there is a new hull, there may as well be a new gantry. orrite so ill make a slap-up mould. or just buy vaccuum gear now.

I've sussed out a (hopefully more effective) new rudder flap adjustment system using a piece of string and a cleat and some elastic/pulleys etc. we'll see how that goes.

also my stsainless cables inside the foils are going to get replaced with some nice smooth fibreglass rod. the centreboard first, the rudder may need to wait until after the states. Ultmately there will be a bladerider style tube through the foredeck so i can do away with the friction-friendly throttle cable. and a new wand hinge mechanism.

i have my work cut out for me i guess, but im on holidays this week so ill get right into it and see if i can't get a foil laid up and a gantry laid up by next friday

to buy:

carbon.

release wax and PVA release agent

resin

fibreglass rod & end fittings

new wing tramps

some rope and pulleys

to bring us up to speed

2008-01-07T14:36:00.000+10:00

I bought the boat from a nice bloke in the northern territory at the beginning of 06. I'd never seen it in the flesh when i picked it up from the truck depot and was all round pretty stoked with it. The bare hull weighs about 15-18kg with fittings on. The wings are carbon (fibreglass?) sailboard masts. carbon stick, sail was almost dead. The boat is rock solid though, and as a first moth and a test platform for ideas it is very satisfactory.

Tacking out of the manly boat harbour the first time was interesting. And on my second sail i broke the wings; the middle of the aft bar and the port tip of the fore bar. I didnt realise that the aft wingtips needed to be tied together. after a pretty long swim some windsurfing dudes helped me get the boat up the rock wall of the marina. repaired:

also the t foil came off the rudder, i took the opportunity of saving myself about a kilo by doing away with the old gnarled rudder box, and re'built the rudder; the old blade as a one piece arrangement with a new T-foil made out of laminated balsa and a carbon tiller and tiller extension. this made the boat much easier to control. i also raked the rig back lots, and replaced all the ropes and most of the blocks, both changes were winners. how someone managed to get it around the course with the previous setup i dont know, but i take my hat off to them.

That all went ok for a couple of sails and I started looking into hydrofoils. Then my flash looking one piece rudder snapped while bearing away one day. another hour in the water, finally picked up a tow back to the harbour, and after that hydrofoils looked like a very good option.

My first hydrofoil mould.. was a work of art, but not so much of science or engineering. we wont go there. important lessons learned.

The second moulds used a thicker NACA 6-series strut section, rather than the NACA0012. This benefited from having a more rectangular shape, and being thicker, and hence a stiffer strut. the mould could be bolted together to form the complete foil. The lay-up took 2 days per foil - all the carbon in one hit (6x400g uni, 1x200g twill on the outside and 1x300g double bias on the inside) and peel ply. Then a 200kg/m3 foam core set with a wet Q-cells bog between the carbon bits, and the whole thing was bolted together and pre cured, before being baked at 80 degrees for 24 hours. The result was precise, with a nice finish, no bubbles, and very stiff, and tense. it resinated when you knocked it, like it should.

I made an adjustable fairing for the foil to fit into my existing centreboard case - a case within a case. all the control systems were very similar to what the prowlers were running at the time. i purposely made the foils a bit long, knowing i could move the rudder gudgeons and re-drill the centreboard to shorten it if need be. first test was in the manly boat harbour in 5-10 kts, and to my surprise all 45kg of boat and 75kg of skipper went rocketing out of the water on the first puff. i foiled around for 10 minutes and called it a day. the control systems really didnt work that well, but i really didnt care at that point. stoked.

Second time out it was a bit breezy and a bit choppy on the bay. The sideways force on the long rudder twisted the aluminium rudder gantry that was nicely built but clearly not designed for those loads. I had a scary ride into the harbour with the foils 10 degrees out of allignment.

At this point, it was about 3 days before the nationals at cootharaba and i knocked up a new gantry overnight which was crap, but lasted the nationals. just. and shortened the foils to 850mm, though didnt cut them off, as the lake was meant to be a tad shallow. and it was definitely fun foiling (some of the way at least) into the shore when everyone else was getting out in neck deep water.

nationals:

the day before the regatta i went out on the lake and foiled around fine. need some practise. just before the invitation race i had a big crash and was not suprised to see the main foil in 3 bits. At the particular point when the boat is nosediving at 20 degrees doing 15kts, there is so much load on that foil from such a wrong direction that i couldn't see how all the others managed to stay together. in fact i couldn't see how mine had survived quite a few such crashes. I got to the shore with my few shredded bits of carbon hanging a bit limp off the bottom of the boat and it became apparent that all i had to do was tie the bottom plate to the top plate and strut. lots. then she'd be able to resist that negative load that i didnt really foresee. Sailed the regatta as a low-rider, (had to bite the bullet and do an overnight repair on the broken standard rudder) I found the boat to be fairly quick on the breeze but not downwind. maybe that was to do with my mast rake... or my lack of balance... did orrite in the end i was pretty happy. Brent ended up beating me, but i did finish the regatta with two DNFs.

anyway over the course of the regatta i broke:

2 sails. (one was emo's, i hope that fixed up alright)

1 hydrofoil.

1 dacron tramp. (stitching)

1 repaired t-foil rudder. (sheered off on the second last day in 25kts at the bottom gudgeon)

1 makeshift gantry. (didnt actually break, just elongated the holes where it attached to the boat)

So a year later im into it again, i have an opportunity to try some new ideas. i need a new foil, a new gantry, a new tramp, a new sail and the control system needs an overhaul. give me a month to psych myself up.