Hydrofoil monohull...

Very cool craft, even for a monohull... http://www.freidling.com/explorius.html

Stylish, but what is keeping it upright while under sail?

And what about swells and waves? All their renderings are in completely flat water.

The art is beautiful...but the stability is highly suspect...It looks incredibly more stable upside down.

Looks like the foils could catch a lot of stuff. I thought the foils going from the front to the back looked good. They would not have been such trash or kelp catchers in the second drawing Yeah a bit unstable but until someone sails it the concept will not go further.

Picture if you do not want to go there:

I dont think it will ever sail, but I would like to watch the video of when they try <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
To me it looks like an art-concept from somebody who dont know much about sailing. Looks cool, but no chance of it ever sailing, and foiling.. Reminds me of the royal swedish Man'o'war "Vasa". Very stylish and pretty, but going over and sinking after just a few meters.

http://en.wikipedia.org/wiki/Regalskeppet_Vasa

I promise you that no stability calculations have even approached this concept. The idea of foils like that on a big cruising cat might be interesting.

Looks like some architect gone wild with CAD software again...sigh.

If they're dihedral foils, all that is needed is to space them far enough apart transversely to gain stability. Just like a cat really, the wider the hulls are spaced, the higher the stability. This only works when it is moving fast enough for the foils to produce sufficient lift though. One of the original hydrofoil moths (Brett Burvills I think) had dihedral foils mounted to its wings. It was banned because it was too stable, the moth class rules against multihulls were invoked.

It could be done, but would be better to invest in some actual engineering/naval architect design and a prototype first.

Having simply stalled the foils on a pretty standard Henderson SRMax before (a somewhat high performance 21 monohull), I can promise you, you don't want to make one tiny mistake and stall the foils on something like that. It will be on it's ear, or worse, in a skinny second.

True. But the same counts for planes if they stall, the trick is to avoid stalling by specifying the correct design envelope for the foil. Generally speaking, the larger the foil and lower the aspect ratio, the less likely it is to stall. Large foils would be very prudent on this thing, less likely to stall and would provide an amount of bouyancy at slower pre-foiling speeds. The size I envisage off the top of my head for a 40' (similar to the sketch) would be about 4m chord, 10m length, 0.3m at thickest point and about 10m span between foils. This is for both bouyancy and height "control" in waves.

Personally, I don't think it is feasible, you may as well have a trimaran with banana boards, much safer.

Looking at the 60' tris going around atm though, it looks as though they are converging closer to the concept design. Less outer hull volume on the tris (for less windage) with larger banana boards seems to be the trend, if it is class legal. At the extreme range of this trend is the dihedral foiler monohull...

As the tris continue on this trend they will find a happy medium, which probably won't be as extreme as the concept monohull.

Guys:

This is the foil monohull you need:
http://www.int-moth.org.uk/
Will they ever make the other boat? Or is that a pipe dream?

Doug