Fastest Sailboat on the Planet!

[daiquiri]

Transferred from the thread http://www.boatdesign.net/forums/sai...ord-30137.html :

Fantastic!
And these pics of Hydroptere are awesome:
http://www.sailinganarchy.com/fringe...%20Grenier.jpg
http://www.sailinganarchy.com/fringe...HyTR50_147.jpg

[daiquiri]

I have just noticed an interesting thing in the second pic...
It appears that the water spray from the leeward foil impinges against the ama and gets deflected downwards. If that is true, then an additional lift force is created at the leeward ama, augmenting the overall lift force, diminishing the heel angle and increasing (I'm guessing here) the hydrodynamic efficiency.

Does someone know (many well-informed people in this forum... ) if this is real or is it just an optical illusion produced by this particular viewing angle? And if it is real, do you think it was an intentional feature of Hydroptere's design or was it just a lucky by-product of this particular configuration?

[Doug Lord]

I know that the stepped amas were redesigned to allow a less draggy release from a wave impact-I imagine any positive effect from spray deflection is a by-product.

[daiquiri]

If that is the actual spray behaviour, then they could use it to generate more lift by deflecting it intentionally. A deflector plate (magenta color in the attached pic) could be installed on the ventral side of the foil, at some distance above the water surface, in order to deflect the spray downwards and generate additional lift and heel-reducing moment.
I know it is nothing really new, I am just thinking out loud by looking at that photo... What do you say?

[Doug Lord]

It might be a good idea but it might also have a negative effect on liftoff since it would be immersed when the boat was off the foils....

[Boston]

less spray = less drag
I think its like the F1 cars
they always want to use clean air to control there dynamics and use as little as possible at that
my guess is that once the air or water is "disturbed" ( like being thrown airborne for instance ) it becomes a liability rather than an consistent source of dynamic stability
better to reduce the condition that waists the energy throwing water in the air than try and create a new lift surface when thy clearly have the lift they need

my two cents, and Im sure someone will come along and take my head off for it, but it rings true with all Ive learned this last year or so of reading along

cheers
B

oh
and good observations Daiquiri
I missed the spray interfering wit the boat like that and Ive been an avid follower of this thread

best
B

[daiquiri]

I have checked out on youtube, there are a lots of videos of Hydroptere in action. In this one, in particular:
http://www.youtube.com/watch?v=dFGS7YCDk3Y
the spray (or should I rather call it "the jet"?) created by the leeward foil is clearly visible at the beggining of the video and it looks pretty impressive. It impinges upon the ama and gets deflected downwards, but in a rather uncontrolled way.

I think that a deflector could be designed in such a way to canalize this water jet in a more efficient way and create a limited but useful increase in lift, as in my above (rough) drawing, with very little added drag. As Boston has noted, this sidewise-thrown water carries kinetic energy which is actually pretty much wasted, imho.

The added lift created in this way could allow to unload the foil to some extent, and thus to have less lifting surface in the water and less hydrodynamic drag. And, since the lateral point of application of this additional lift would be placed further away from the boat's CG, it would create a heel-restoring moment which could somewhat diminsh the heel angle and increase the aerodynamic efficiency of sails, too.
I know it might seem like a very little gain, but when you approach the design (and physical) limits, every detail becomes important, imho.

I would like to hear opinions on this from other people here with relevant experience.

Cheers!

S.

[Gary Baigent]

Good stuff Daiquiri - but I think this is a serendipitous result, although obviously the float plane type stepped amas are designed to definitely throw water away and provide some lift coming from the intense and powerful foil spray - but more importantly are designed that way to help break free from water surface in lesser winds - but I'd guess, pretty sticky in below 5 knots wind. Think of Yves Parlier's stepped hulled ORMA catamaran, excellent in higher winds (but threw clouds of water and spray) but not good in light conditions.
But the stepped floats are an interim transition thing; the boat is a true flying foiler, meaning the lifting foils are the most important aspect of the design, they're the boat's raison d'etre.

[Doug Lord]

From Foilers!-- http://foils.wordpress.com/ :

Alain Thebault, again, would aim now around the world in 40 days! Around the world envisioned in the Hydrofoil max derived from tests performed on the Hydrofoil. ch. Read on Sport.fr or 24 hours. Good news for me (!)
12/7/09

[Doug Lord]

Hydroptere.ch is in build. She is a 40' cat with stepped planing hulls, a central pod(like the decision 35) and surface piercing foils. Can't find dimensions but the thing looks wide in renderings.
http://www.hydroptere.com/_en/actu_d...actu=59#centre

Launch summer 2010....

[sysfx]

The text speaks of archimedean mode and foiling mode only, but they will certainly use foil assistance too.
The design is even closer to my boat's than BMWO's! Not too bad for something that started ten years ago.
Luiz

[Doug Lord]

Excellent new -and historic- video: http://www.hydroptere.com/_en/galeri...re.html#centre

[Doug Lord]

I urge anyone with a real interest in high speed sailing to watch this video!!!
Toward the end the 2008 pitchpole is shown as taken from the mast tip-this whole video is nothing short of incredible. Here is the url again:

http://www.hydroptere.com/_en/galeri...re.html#centre

[Chris Ostlind]

Doug,

Just because you have a Jones for foils, does not mean you should post the same information twice in succession.

Some folks call that redundant.

[DocScience]

http://www.hydroptere.com/~hydropte/...xi.html#centre .
Notice that in the proposed Hydroptere Maxi , they are moving the main foils a little bit farther forward, which I assume is to reduce the tendency to pitchpole. Also, they are tilting the mast backward to a bit of an angle, most likely for the same reason.