#96051 - 01/16/07 02:19 PM
Re: Back on Topic
[Re: Nieuwkerk]
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old hand
Registered: 09/23/05
Posts: 1184
Loc: 38.912, -95.37
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and Wouter asked to make a choice, and reasoning behind our choice, of 3.66, 3.90 or 4.00
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John H16, H14
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#96052 - 01/16/07 02:31 PM
Re: F12 means what then?
[Re: Nieuwkerk]
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addict
Registered: 04/05/02
Posts: 695
Loc: Ft. Pierce, Fl. USA
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Will the water line length of the F12 be equal to its length overall? Waterline length is commonly used by some power boats to define length…On the huge SKA circuit (Southern Kingfishing Association) they have a 23’ and under class…but it goes by waterline length, not length overall…so some of the hulls end up being well over 26’ even though they are called the 23’ and under class.
If the bow of the F12 were a bit more sloped back aka “wave piercing” and had a transom that slopes forward, maybe you could steal a few inches of increased length where it counts, underwater. If somehow the "loaded" (that is including the defined designed crew weight)static waterline length could fall into the 12’-6” range (3.65 mtr) would that be enough to satisfy the group that is concerned about it not technically being 12 feet? That is, could they then be comfortable in defending the F12 as being rounded down to the next nearest foot?... which is 12 feet?
What we are really talking about is playing with words…Wouter has made a strong case for increasing the length to 3.90mtr, the numbers don’t lie. This is one of those times were it only costs a dime more to go first class (actually it's free)…why ride in the back of the bus? You can always “dumb the boat down” with a smaller less efficient rig.
By going to more performance oriented hull, the boat will allow a wider spectrum of users as Wouter has been saying from the get go. Simply by changing out the mast and sail…just like we do for windsurfing…each sailor could pick the right size and style sail for their weight, strength, and sailing experience. No one could gripe that they were being treated unfairly because everyone could choose exactly what works best for them.
To recap…a waterline length of 12’-5-19/32” (3.80), an overall length on the bottom of 12’-9-17/32” (3.9 mtr) the difference between the waterline length and over all length would only be 3-15/16” (.1 mtr) Surely a creative designer could tweak this design to get 4 more inches of length below the water line. We could have our cake and eat it too.
Regards, Bob
Edited by Seeker (01/16/07 02:38 PM)
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#96056 - 01/16/07 11:03 PM
Re: A choice to make ...
[Re: Wouter]
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old hand
Registered: 09/23/05
Posts: 1184
Loc: 38.912, -95.37
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Reading the 58kg is your target weight for prototypes, shall we go ahead and make orders today for 3mm ply? Allowing a few weeks for delivery? 
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John H16, H14
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#96058 - 01/17/07 02:13 AM
Re: A choice to make ...
[Re: _flatlander_]
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Carpal Tunnel
Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
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Well,
I think I've got it all done now. Last items seemed to have come down pretty quickly. Of course building the prototype is alot of work but the basic design is pretty much done. I even got some tricks that could allow making the hulls lighter, just in case. I also was pretty conservative with the weight calcs so you can drop some extra resin here and there.
I even got the costs sorted out to a large extend. If you really want to save cost then you have to build your own sail. Paying a sailmaker to do it for you at 610 Euro's is quite alot when the basic boat without a sail is only 2250 Euro's. And this last quote still includes the dotan rudders a 712 Euro's. If you are going to build this yourself then the ready to sail boat could be as inexpensive as around 1500 Euro's (1950 US$).
When you got more stuff laying around like blocks and shackles the price drop a little further.
I guess that soon the next stage will be to prototype the hull in cardboard at a 1:4 scale, trying to find the right panel layout and then prototype it in real life size.
I think the panels can be twisted quite alot, this should improve hull shape without having to go to compound curves or steaming the ply. It will allow a more pronounced V on the keel at the bow and have it run much flatter near the sterns. But also the sides can twisted a little bit to give hull a raked back bow and a modern wavepiercer bow section. And ofcourse the sterns can be twisted in a little bit as well if that improves looks. The deck is just curved in one plane, should be easier to close the hull off that way.
Yeah I think that with a trick here and there a pretty nice multichine hull can be made. Still I propose a square box shape like the arrows and arrafura's to test the rig and mast setup. These need to be prototyped first to see if the design works as intended. There will be no need to start right away on the more complex (and better looking) hull.
And then spend some time working out the right sail cut.
Wouter
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Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
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