Hi Dave

It looks like there are 2 distict types of sailing foilers evolving

The true foilers designed to raise up above wave tops ,-
theses generally with surface foils mounted on the sides of the craft like yours and the larger Aussie cat foiler -
{can't wait to see the 60 ft version for a transatlantic race attempt } ---
and the semi foilers which seem to be thru hull canted board types ,-like catri http://www.multicascos.com/ingles/catri_english.htm

These seem to partially raise ,-or 90 % lift ,-which may be the ideal multi use craft type for ocean conditions , designed with proper hull form .
The more extreme forward locations of foils and masts may be the next area of development needed for these craft to overcome top speed limitation ,--developing some lift from the sail plan as well as the foils .

there are some other good examples of thru hull canted board types ,-in smaller cats ,-do any have references or design sites on these ? -thanks -

Seems like the forward foil/board rake along with cant of the foils or boards would also improve the angle of attack as compared to craft angle and attitude .

Is there an established ideal rake and angle degree of cant,--the verticle from horizontal surface {end forward view} looks like approx. 45 degrees
and also forward rake ,-looks like this would vary with bow down tendancies of hull design ,--probably why so many of these designs have huge bow sections and narrow sterns , which not only keeps them level before lifting but also assists in dropping off the foils suddenly .
Would like to retrofit and experiment with some canted boards and shapes on existing cats on the thru hull type,
Some designs have already had success with this , might be fun to try to take it to the next level .

thanks
Carl

Excellent! Carl has again grasped the essentials: I would say that there are 4 main multihull types and one bicycle monohull type.
1. Catri and the older French tris used foil-assisted lifting on their forward system, never intending to fly completely out of the water.
2. L'Hydroptere has very large surface-piercing foils angled at about 45 degrees between the hulls and flies at speed quite high above the water: thus crashing may hurt.
3. Sam Bradfield's new inverted T-foil design will be racing to the Bahamas soon, with Rave sailors manning the side: these all fly above the water. Some claim that this design never pitchpoles but I have watched it happen! When they collect weeds they all stop.
4. The monohull Moths fly whether on outrigger-type surface-piercing foils or bicycle T foils, and cannot be retracted out of the water.
5. My rigs and the Spitfire concept boats all fly: in less air the foils can be lifted out of the water for efficient sailing -(mine lift easily).

(Its a LONG way from here to Labrador and the land of the Newfies to go to test foilers in salty ice water).

Bill Roberts quote about the round Barbados race: "The locals told me the race was 88 nautical miles around the perimeter of the island. Sailing North up the East coast against the swells was very slow and jerky, no fun".
The boat would accelerate then head into waves and stop.

Hmmmmm- What if Silver Bullet was on foils and could sustain foiling speed?

You probably mean older and latest French tris.

Most (if not all) Open 60 tris today use Bruce foils. The latest ones also feature rudder foils.

It seems that the Open 60s have been designed to sail in displacement mode. Judging by the size of their foils the lift provided is close to 20% to 25% of the displacement, which is not enough to plane.

I see the Catri as something different from the Open 60s:

1) It is a small cruiser, not a big racer.
2) It is designed to reach top speed without flying two hulls.
3) It has a unique stabilization system.
4) The amas are almost half in displacement (110% X more then 200%).
5) It folds.

I am not sure if they should be put together. They just look alike.

Carl,

Regarding the inclination of the foils:

As far as I know, Bruce demonstrated that if the foil's lift points towards the center of sail, the boat is stable when sailing fully foilborne.

As a consequence, the daggerboards inclination angle is a function of mast height and total beam.

If the mast is taller, the boards should be more inclined (closer to horizontal) and if the mast is lower, the boards should be closer to vertical.

Wider boats require less inclination, narrower boats require more inclination.

now that's interesting

Thanks Luiz -Dave -Jake and all ,-it is interesting as Jake noted .

Thought that would be ideal --alligning the foils at a basic right angle or roughly 90% angle to the sail plan CE
though spin to non spin calc thought thru as well .

Dave ,-on going thru waves with a foiler ,-It seems there are times in larger seas where the craft is actually traveling uphill ,-against gravity more , --no matter how large the craft is ,some effect remains though proportional to craft /wave size ,-
No matter how potentially fast ,ocean going sailing craft are subject to the hulls going thru waves at times .
bottom line is they should be designed this way ,-unless the goal is protected water sailing in only a certain wind range ,-just fun foilsailing ,-or a speed record type craft

maybe a set on this one added for fun
http://www.morrellimelvin.com/ss60_April03.html


Like Sergy,s inflatable cat ,-{other post }-
now if we could just fill it with helium and add Dave,s foils we may really have something

have fun
Carl

Jake,

Last night, we started a page for our foiling videos. Go here for our beginning collection of links: http://www.windriderforum.com/phpBB2/viewforum.php?f=12

What a great idea Carl!
We could make boats lighter then air, then use the foils as wings and actually fly...

Now seriously, I wonder why PVC foams and honeycombs aren't sold with a "helium filling" option? I think it's feasible, at least in some honeycombs. Lighter foam or honeycomb would be especially welcome in airplanes too.

Re: Lighter Foam for Luiz- there have been several threads on this site about this topic. Most closed-cell foam is made with a chemical blowing agent of chemically-generated nitrogen. Helium cannot be generated that way since it is a noble gas. Maybe hydrogen could, but would get out through the plastic cell walls since the H2 molecule is so small. In short, not enough advantage would be gained.

Oh the humanity -hydrogen beach cats -
http://www.vidicom-tv.com/tohiburg.htm

Some have already tryed filling air bags in the hulls , but the volume for helium is small ,and hydrogen a little too dangerous .

Seems we will all be powered by vacume zero space and {wiggle } in the future --makes you wonder about the billion currently designated to help develop hydrogen cars and vehicles to replace gas .
Land sailing yachts would be great for all , but a little tough in the morning commute to work with the wind on the nose tacking within a 66 ft wide highway easement ,--
STARBOARD - #@%%$# :grin

thank god for the creative dreamers ,-the world would be a very boring , diminished and conformist -limited place without em -
http://www.windjet.co.uk/water/competitors.php

Ok, so ligkht gas foam is difficult to manufacture, but maybe a light gas honeycomb could be done. I've seen one that had plastic walls and a thin plastic surface. It seemed quite easy to fill the cells with anything before adding the last flat surface.

Yup, hydrogen would be dangerous.. especially with the three leprechauns living in my hull where they smoke their little green pipes: I keep asking them not to provide this source of ignition on my sailboat.

Red hulls + Hydrogen honeycomb = Red Zeppelin

Hi Dave,
Sailing up the East coats of Barbados on foils would have been fine. All it would have taken are legs to the foils about 8ft to 10ft tall.
This is the same problem that exists with the production foil boats today. The legs are too short to get the hulls up out of the waves in real water and the drag pulls the boat down off the foils, slows the boat down until it can't be foil born. The foil boats are similiar to sailboards: They go really fast in the French ditch but put them on real water with real chop and they really slow down. Biscayne Bay is one of the best "protected water" sailing areas in the world. One would think it would be covered with foil boats but it is not. Why not??? They can't get up. Some foilers have had power boats pull them up on their foils and them cut them lose to sail on their own and if the chop is 2ft to 3ft, they can't stay up on the foils. We need some long legs to those foils! Get the hulls up out of the waves and they will fly.

Bill,

Your wish has been granted by Nigel Irens and Sam Bradfield and they plan to cross the Atlantic with it. Pics here: http://www.multihullboatbuilder.com/scat/ Are you ready to place your order?

Boats with short foils (vertical) won't fly in a chop but the boat at the site shown here can handle a two to three foot chop because it's legs are almost six feet long. http://www.windrider.com/wrrave.shtml
The point is moot with the Rave because once a 120-160 lb. pilot is going 12-13mph in wind of 10-11 mph, it's liftoff. Sustained liftoff, not a hopping. Chop is no problem with the Rave. I've hit a two foot chop off the shore of Quietwater Beach near Key Sailing in Pensacola. Also, out there behind Tristan Tower. An early French review of the Rave mentioned the most strange feeling of riding so smoothly above a big chop. But on a boat that only has to get up to 12-14mph for liftoff, you don't have to wait for the choppy weather.

Once the Rave is up the only resistance is to overcome is about 10 square feet of foil surfaces being pulled by 300 sq. ft. of sail; the boat simply takes off like a rocket and the trick is to keep it from flying out of the water. Flaps keep it flying level. The pilot on a Rave can fly his foils as deep or as shallow as he pleases. The proper attitude is to keep it skimming just above the surface, bow down.

The most common reason foilers can't get up in Biscayne Bay is all the grass and that's a shallow bay in places but I've flown there. It was lonesome.

Regarding them not being popular, they're expensive and the economy hasn't been this bad since 1958. Also, boat manufacturers are terrible marketers. Foilers are a tiny niche market in a shrinking part of sailing whose overall demographic has been shrinking for quite some time.

The problem with the Hobie in a chop is those little fragile skids riding forward of the bows. A chop plays hell with those things; a design limitation if not a flaw. That's why you never see a Tri-Foiler in water that is only a little confused and relatively flat.

The Rave, however, with T-foils about six feet deep will sail eerily smoothly above a three foot chop. Once foilborne on the Rave the chop is just something to look at. The Rave's foils are riding through the water below the chop and the wands controlling the flaps on the port and starboard foils are slapping the top of the chop so fast that the wands don't a chance to drop into the short troughs so they ride pretty much at a level as if they were on smoother water. The Tri-Foiler can't do that with their skid system.

You're correct. No foiler with short legs can do it in a chop but a foiler with more than 6' long legs would be impractical unless your crossing the Atlantic for which their is a 37' version of the Rave with T-foil legs that are just plain scary. I'll post that web address when I can find it.

Dean,
Most people don't buy a "pig in a poke". Your experience with the Rave is quite different than what I have observed on the Saint Lucy River. The Rave dealer that sold more Raves than any other dealer in the world use to demonstrate the boats on the Saint Lucy River in Stuart, Florida. I have watched them fail to become foil born many many more times than being successful in the effort. The problem was not lack of wind but too much 2ft to 3ft chop. The dealer has since moved on to other endeavors. The Rave foil boats have attempted the Miami to Key Largo Race many times....no success.
The swells in Barbados were 6ft to 8ft. With the foils 2ft under water and the hulls 2ft above the water, that requires at least 10ft tall legs and these numbers are not what you would call "big seas".
Team Philips thought they had tall enough legs holding their POD up above the hulls. But they found some seas that tore their POD off its legs and the boat was abandon.
Dean, 6ft legs are not going to cut it out in the real ocean even in a small storm or just 30 knot winds and normal waves.
Bill

Yes, I bought my boat from Eric Arens in Stuart. I've sailed with him several times in the St. Lucie River. Eric went back to the F-Boats. Eric and I have tested some simple modifications on our Raves in a short chop in the north fork.

Eric also used the St. Lucie to teach the owners. If you consistently saw Raves hoppin' and floppin' out there you can bet that it was Eric helping someone to get their wings and if the newbie was in a light chop he was probably a little askeered and timid with the machine. Ther are are eight basic lines to control while steering with your feet. It's a lot more complicated than a couple of sheets and a tiller extension while hanging on a wire. Yes, during that time you look pretty stupid or the boat looks like a failed design.

Eric had a marketing disagreement with the factory and gave up the franchise to the people that bought his Corsair dealership.

I didn't mean to imply that the 17' Rave would be an oceangoing vessel; only that it's deep T-foils can easily handle a chop unlike foilers with shallow foils. Even so, in 1999 a Rave easily made the trip from Key West to the Yucatan though I personally think that a little crazy. Here's his story: http://www.pan.com/folksinger/Further.htm

The Rave's big brother "SCAT" at 37' and with foils that extend to ten feet would be the one to take on the big water. I think that Nigel Irens design would have a good chance out there.

I know quite well ALL the few sailors that attempted the Miami to Key Largo Race once in a Rave. That cannot be construed as "many times" and, like my effort in the Round The Island, it's better to give the guys credit for making the attempt while knowing that they will be in an uproven boat and among much faster boats while hullborne. It's much easier to show up in a cat and know that the race will be a piece of cake, but everybody does that. Some people like more of a challenge than the same old thing.

Hello people interested in foils,
Foil boats and the foils are not as simple as what I am reading on this thread.
First, fixed foils won't work/fly. The foils have to be modulated because the weight to lift is constant but the ability to generate lift increses with the speed of the boat squared. Once a craft is foilborn and accelerating something has to control the lift or else the lift will continue to increase until the foil stalls and then crash. Once a foil craft climbs up on its foils something has to keep the total foil lift constant as the craft changes speed while up on the foils. This is acheived by changing the angle of attack of the entire foil or by varying a trailing edge flap on the foil to control lift. The secret to foil boats is not the foil shape; it is to "control the foil" to generate constant lift, boat plus sailor, over a useable speed range.
Bill

Bill,

have you not even seen the wands that ride the surface of the water to control the pitch angle?

It IS pretty simple, even a uneducated, non-engineer like me can get it.