Does an Americas Cup boat have to float?

cameronke

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Has a submarine yacht ever been tried? Imagine that the whole hull was sumberged so we are no longer slowed by trying to climb our bow wave (see JohnM's baffling question). Only the mast and sails break the surface and the boats depth just below the surface is controlled by a hydrofoil system.

Navigation could be effected by a camera obscura type device in the mast :)

OK so International moths and the open development classes have taken off on hydrofoils so howzabout a submarine one?

OK its Sunday, raining and Im bored

patent applied for........

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jimi

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Pete Goss tried that as I recollect with a wave piercing hull on hid ill fated venture?

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AndrewB

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Forget it ...

... a submarine faces huge water resistance. The essence of go-fast is to have as little as possible in the water.

I'm working on a top-secret wind turbine that will create a hovercraft effect. 50 knots guaranteed. Interested sponsors may forward their readies to ...

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Spuddy

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the sailing submarine eh. Could have the sails in camouflage I suppose for military use.
There was the K class steam submarines. I think they had collapsible funnels and took ages before they could dive because the fires had to be put out first. On e skipper is supposed to have said , " my ends going down, number one. What's your end doing".

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StugeronSteve

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No, but in the very least they would need neutral buoyancy. I would have thought that the friction over the surface area of a fully submerged hull would reduce the efficiency drastically. I'm not sure, but I thought that there have already been a few America's Cup boats that didn't float (not for long anyway).

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Sybarite

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It reminds me when, long ago of a summer evening I used to invite young ladies to the seaside in my car to watch the submarine races...

John

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BobE

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Surely 'tis all to do with wave making resistance. Nuke subs are quicker down below 'cause they don't make waves.. It's the interface between the air and water that screws us up..
So what about a kite to support you and provide the motive power with a steerable foil ( basically a centreboard/rudder combo) under the water to provide the lateral reistance. These two hydro/aero dynamic units to be joined by piano type wires which should also be the control lines for each unit ( foil and kite). Minimum disturbance of the interface...No Hull... No horizontal foils to provide lift and thus make drag at the square of the velocity.. Wish I was 20 years younger !!
That would make a real cat's (or kite's ) cradle ;-) ;-)
Or doesn't any one else read "Catalyst"?? (The journal of the Amateur Yacht Research Society)
Cheers Bob E..

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Jacket

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There was talk of trying this in international moths. Have the 'hull' as a submerged bulb, with two struts from it supporting the mast and a trampoline for the sailor. Dont think it ever got built though, due to the problems of trying to keep the thing floating at a constant depth below the water.

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Twister_Ken

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You sure?

Go to the local swimming pool. Change. Get into water. Push off from side of pool and glide as far as poss on the surface.

Return to side. Take deep breath. Submerge. Push off from wall and glide as far as poss underwater. Surface only when stationary (not when you run out breath!). Which shove got you further?

I used to be able to glide a width underwater when at school, but I could never glide a width on the surface.



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MainlySteam

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How do you make it stable?

Stability is imparted by the lever arm (GZ) between the centre of gravity and the centre of buoyancy of the vessel. I would assume that a submarine hull in neutral buoyancy state (ie neither trying to float on the top of the sea or sink to the bottom) has no centre of buoyancy.

Maybe there is some secret?

{Maybe it does have a centre of buoyancy if you keep all the air in the top half of the hull?}

John

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AndrewB

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Re: You sure?

Eh? For most people it's impossible to glide underwater without added weight. Active swimming is needed to keep down.

I also used to do this at school, we had an event in our annual swimming gala to see who could get furthest, the 'plunge'. From memory I think the school record was about 12 metres. Of course, so much of the body is in the water even when surfaced that it makes little difference whether or not you are under or floating.
 

jamesjermain

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Re: You sure?

This is the first time I have ever heard of someone else doing this daft sport, which I thought was unique to my alma mater. You didn't go to a certain establishment in deep Dorset founded by Edwardus Sextus by any chance?

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ParaHandy

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Baggy trunks?

... depending on how baggy TK's trunks were, the lad might be neutrally buoyant? hence energy to kick mass underwater long(ish) distance will be less ....

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dwatson

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Unfortunately under the current rules:
10. FREEBOARD
10.1 In measurement condition the yacht shall have the following minimum freeboards
measured to the sheerline:
(a) Minimum Freeboard at FLM: 1.500 m.
(b) Minimum Freeboard at 50% LBG: 1.265m.
(c) Minimum Freeboard at ALM: 1.200 m.

Although you could launch your own challenge although you may have let the cat out of the bag about your secret weapon!

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