Tuesday, November 11, 2008

new stuf (hull, wings etc.)

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


Doug Culnane said...

Looking at your boat here are some additional comments:

I bust my V foredeck with the forward strut. The forward load on the king post if FUCKING LOTS so I would be putting loads of carbon in that king post but even then I am not sure it will be staying in the boat, with no bulkhead underneath, and little boat to stick it too. I can not see that lasting long.

Like I said in a mail the bow sheer is on minimum on my boat. Not for nose diving because that is job of the foils to prevent but when low riding in little wind and flat water... However the back is too big so I would chop 5cm off the sheer aft. If you dive then I agree you should go with it and the deeper underwater you go the more you have protected from breakage, by your flying body.

My gantry is fixed the rear wing bars as the hull is very small and week. I would say this is better than your layout. (IMHO but this is nit picking)

The front wing bars look very perpendicular to the hull. Structure here would over ride letting the boom out as the boom nearly always on the center-line. Maybe I am wrong but I would check the angle with other boats.

The boat look awesome. It is the next iteration of Lord Flashheart, and looks like a foiling Moth of the future not some flying hungry tiger. I like the tramp and thought of doing something similar on my boat but did not have the balls.

There is nothing wrong with Adams hull shape so building female moulds is worth doing. However this will make my Flashheart look terrible in comparison.

Adam and I released the Flashheart under the GPL so if people want the file of your modify lines based on it you will have to supply the data. This is very important because I will probably want to build a new boat at some point... ;-)

I am very excited to follow your build.

All the best,


Karl said...

Nick is it possible to keep the aft deck flat or a little inverted V shape? Maybe carry that upward curve from the mast area all the way back to the stern somehow? Then you could do a right/left half tool and join on centerline with no aft deck to fiddle with.

Just a thought. Might ask you for some lines when I get to that stage.


nick flutter said...

hey guys thanks for the comments.
a few things:

- yeh the kingpost is difficult, i was thinking of taking it right through the boat, so its a cantilever. i know theres lots of load, especailly when the boat pitchpoles and the vang loads are complimented by the rig trying to become a hang-glider. ill either work out a tensile tie to the centreboard case that wont interrupt the vang, beef up the post or put in a strut. i micht rake it more too. 12 or 13 degrees? the worst thing you can do is kid yourself about the loads hey.

-the freeboard aft is -5cm on flasheart. so is the bow, so ill raise it up a little. i think wave peircing dynamics will pay for some lost freeboard there.
thats funny about flying bodies i broke my stem block the other day with my chin!

- gantry to wing bars / slpoing transom is sounding better and better, i might actually fix it to the wing struts if the rear wing bar remains raised, that way the wings can come off for travelling no trouble.
- the front bars are from the measurements on your 'design brief' page, as far is i can be sure i typed the corretly, im looking for any excuse to rake them back more. just need to make sure i can let the sail out to stop the boat before the start, thats the only reason for keeping them out.

- karl your right about the aft deck. its the obvious choice. i will change it. teh idea was to have some points to attach the gantry, and i was going to have something more complex going on there that i didnt model. but ive scrapped that idea. ill use bits of kingpost as struts to elevate the rear wingbar.

thanks for the feeddback!

nick flutter said...

also if anyone wants the rhino file or a dwg at any stage of this, just ask me, ill email it to you.

Doug Culnane said...

Maybe the the front wingbar angle is ok then. I think the shrouds should be 25cm aft of the mast step. It just looks a bit scary so I would double check it with other boats, however I built to the same measurement, and my boat is OK.

Looking again at the tramps I would be worried about falling down the hole at the front. Is it possible to tie them to the kicker attachment and not the back of centreboard? You could do the prowler forward sweep which works great.

A strut to the forestay is maybe unavoidable. I would not go to mid deck like my boat as it destroyed the fordeckdeck and the re-enforcements are now more carbon than the 30cm extra tube needed to go to the forestay.

I too had a low deck the only problem is where to put the fittings. Your boat is even worse with very little pace to glue a fitting to.

The nose is nice and a bit aardvark. This is all good but you are getting close to dragging your wand attachment through the water when low riding in light winds. Maybe do some hydrostats as this is worth getting right if you do a mould.

The more I see the lines the more I like them. It may only be a rendering but so is the Mach 2 from what I have seen ;-) and this looks sexier IMHO.

nick flutter said...

thanks mate i think it looks sexy too! the wand gear will be hidden mach 2 stlye, bow will come up slightly though. i'll fill in the hole a bit, after my sail today in 20-27kts i think id have gone through!

Teknologika said...

Looking good Nick, can you send me the Rhino file pls.

Also, If you want to get the mould cut, I can give you my brother's details and he might be able to cut it for you on the machine we built.

I say might as the full boat won't fit on the machine, and we would have to cut it in sections.



Pearso said...

Looks like youve been busy mate... looks great. hey just a quick message. Sail bris next week not sure if rod has gotten onto you but were doing some sailing there next week. anyways catchya on the flip flop braah