Veal Heel for Multihull Foilers

There are many Mike Nelsons, but my favorite was an ex-navy frogman aptly portrayed by Lloyd Bridges in the syndicated TV show "Sea Hunt". If there was a problem or a mystery you talked to Mike. After much swimming about and the cutting of the occasional air hose he fixed it.

 

Like all good days out fishing the flats... have patience and eventually the prey will rise to the bait.

Thanks, Chris.

 

Chris ,Sadly I found some of the threads over on SA to be not very worthy of the read, there was far too much bias towards the Moth which is a great boat for the lean greyhounds but totally impractical for the fat old farts like me. In truth the Moth is a great platform, but I can already beat the Moth around the course on a majority of ocassions and can average over 19 knots over a 30 second period on an existing cat platform, so why go down this route apart from wanting to get involved in foiling ?

Which leaves this forum as probably one of the better places to seek factual unbiased, totally free information. There are some very knowledgable guys here on this forum who could be extremely helpful to those wanting to experiment in foiling but and here is the big but. We have two posters who seem to be so totally at logger heads that the good guys have left the forum.

One who is extremely enthusiastic about the whole foiling thing that he simply pisses everbody off with his constant postings. Couple that with the fact he has a skin of a rhino, absolutely no political nous and has become so besotted with foiling that he now believes he has invented the whole thing.

The other poster simply has so much free time on his hands that he checks out all the foiling threads even though he hates anything to do with foiling, any ideas are immediately attacked as being unworkable and dare a thread get going its his personal mantra in life to immediately kill it off just in case the rest of the readers have an opinion on the subject. The time it must take to monitor these threads and reply must take up most of his free time.

So boys and girls can we get back to foil design and the practicalities thereof or are we going to continue in the usual manner of useless point making that has nothing to do with foils.

 

Here, here! We can do better.

I think the title of the thread is confusing, it’s nothing to do with windward heel really, and the considerable non-technical content of this thread is a bit confusing also, so I’ll toss in a para on the concept to focus the discussion before I weigh in with my thoughts.

As I understand it the proposed concept is an attempt to combine the Moth’s ability to fly in light winds due to its light weight and low drag, with the greater speed (in more wind) of a multihull due to its ability to carry more sail. What is proposed is a lightweight trimaran with Moth-style foils on the vaka and deployable foils on the amas. When deployed the windward ama-born foil would generate downward force to augment the RM of crew weight.

1) the idea of increasing RM by increasing downward force on the windward ama without using ballast to has obvious merit
2) the extra weight and complexity of the basic concept, compared to a regular moth, need not be very great and could probably be retrofitted to an existing boat ... but
3) during the transition from 2 foils to 3 foils the sudden introduction of offset drag during deployment will slew the boat sharply windward ... and
4) during the transition from 2 foils to 3 foils, as the downward force increases the lift of the “main” foils must be increased in concert to compensate
5) the additional complexity required to fix problems 3) and 4) will likely outweigh the advantages of 1) so just forget about 2)

Assuming it worked, if I were about to launch such a boat in light wind conditions, the first thing I would want to do is remove all the extra stuff to save weight.

It might be simpler, safer, and more effective to have 2 foilers, a Moth-like one for light conditions and a Rave type one to take advantage of heavier breezes. To save cost, perhaps the basic hull and sail could be common.

The concept can certainly be employed advantageously in a trimaran foiler which used ama-born foils. One approach is to use differential incidence. The Greg Ketterman quote in post #13 called it “dynamic leveling affect” or DLA. The differential forces that create the additional RM are applied across the full spacing of the amas with this idea, rather than between the main foil-bearing hull and the windward ama of the proposed concept. Half the force for the same RM means less drag.

There is also the rather scary Happy Feet concept which involves balancing an entire cat on laterally movable foils, see http://www.boatdesign.net/forums/sailboats/kisscut-new-swiss-foiler-29106-3.html

Another way to achieve DLA is by pulling water ballast into the windward ama through a small opening in the windward foil. The additional weight would be gradual and added drag could be negligible if implemented properly. With the ama flying, dumping the water would obviously be done quicker. Nothing new about movable water ballast of course, but I don’t see why it can’t be done on a foiler.

Whatever is done along these lines, it will be at the cost of increasing drag as the leeward foil has to increase its lift. Whether that would leave any advantage from the additional drive available remains to be seen.

 

Thanks Terry. My only quibble is that 15-20% extra righting moment (plus the other advantages of veal heel) for "free" is a substantial "charateristic" of this concept. One that must be designed into a trimaran foiler to be able to work at that level.
For what it is worth, in model testing with the F3 the windward foil would sometimes come clear and when it re-entered there was no directional affect at all.

 

Agreed, Doug. I question how much windward heel RM can provide on a trapeze-equipped monohull or a multihull design. The width obviously limits the angle one can obtain before the windward structure hits the surface or the leeward foil ventilates, although it worked for Rohan.

I think the windward water ballast idea has potential. A foiler should move fast enough for the tanking-up method used by water bombers to work.

Compared to the deployable foil concept, the force couple works across the full span instead of only half, requiring half the force. No downward lift is needed, only upward lift from the leeward foil, so the net drag should be only 25%. On the other hand, it is not going to be a light-wind boat.

It would be fairly easy to try, I think, at least to establish the principle; just an intake and tube to the foil strut.

If it works, there is an interesting possibility that the intake can be placed at a positive pressure location on the upper foil surface, or deployed as a slot, for maximum efficiency, but first things first.

 

Terry, veal heel is good for up to a 20% increase in RM.The angle* of the cross arms needs to be greater than on a "normal" tri to maintain clearance when the boat is heeled to weather. The windward water ballast is a good idea-Hydroptere uses a system similar to the one you describe. It uses an intake on the rudder and dynamic pressure to fill a tank in the windward ama.
I visualize the windward foil generating something around 400lb of downforce(max) on a 18-20' version of the concept boat (a little over 6 cu.ft. of water-could be in the ama- using it as a tank?). Not sure how practical that much water is on a small beach sailed boat. Intake would have to be -like Hydroptere- on the rudder (or main foil?) and that might be tough on a small boat but we know it works well on larger boats. The waterballast system might have less total drag when the boat is powered up-but might be harder to tack unless there was a relatively quick way to get the water to the other side. Worth thinking about.
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One thing that may not have been mentioned is that the maximum effect of veal heel is determined to some extent by how long the daggerboard(vertical strut) is.
The longer the board is, the more the CG of the boat + crew is moved to weather at any given angle. And the result is unaffected by altitude as long as no part of the hull structure touches the water.
=========
I'm posting the sketch* of 'half a tri' again so you won't have to refer back to page one to visualize it:

The 20 degrees angle is from the vertical(and mislabeled--sorry)

 

Well, you've missed it again, Wayne. It shows your lack of depth on the matter and specifically, my direct input on the topic since day one. If you have the temerity, go look it up. If not... here's the summation.

I am not against foiling. Never have been... never will be. I do not think it is the savior of all things sailing and that is not going to change in your lifetime. Foiling is a decidedly minority splinter activity within a much greater and far more diverse sailing community. Multihulls are a small segment of the greater sailing community and they so completely dominate the presence of foiling that foiling is virtually invisible by comparison. One should never attempt to elevate ones importance in the grand scheme of things if one seeks to be taken seriously.

I enjoy the activity (foiling) as a small time expression within the greater whole, but it's going nowhere for the everyday sailor for a very significant variety of reasons. These reasons have been listed on these pages frequently, so I'll not bother to enumerate the list again. You should make yourself familiar with the shortcomings, as well as the possible positives. A failure to do so is a one way ticket to irrelevance.

Your Boy, Dougie, only involves himself with the potential positives while totally ignoring the reality of the shortcomings. He has repeatedly mustered-up overly complex variants without one single notion of the shortcomings they represent. Really, Wayne, I should think that a guy with your apparent gusto would have long ago figured that out and gotten yourself involved with a much more solidly configured source.

What you do not know about me is that I've drawn some five different foil equipped craft in the last five years and rather than bother the readers here with a boat that has little to no commercial value in the short, or long term, I have kept them shelved. Your Boy, Doug, by comparison has no such self-limiting device internally and listens to nothing from external sources, either. He's a One Trick Pony who is deaf to the outside world, constantly churning-out his Rube Goldbergian devices, extracted from the parts department of the local chandlery.

I generally believe in simpler solutions to what is going on within the sailing community, not more complex and more expensive. You want to build a boat for yourself so that you can diddle with the variables until the day you croak, please, my man, have at it. While you are doing so, please have the good grace to rid yourself of the hyperbole associated with your Chosen One and present yourself with some measure of dignity when others provide input; whether good or bad.

If you can do that, then you'll be miles ahead of your guru and just may make a positive contribution to the genre. Right now, I'm not so sure that you get it.

 

This is not sailing but is a nice little foiler that I did the prop design for.

The design point was 7m/s (say 14kts) with 450W on the prop. This was with a commercially available prop that was about 5% less efficient than the ideal. I do not have actual test data other than this video link that I posted on another thread:
http://www.youtube.com/watch?v=jh_RhkejWLw

I think it is a slick little machine.

I generally agree with Chris on the prospects for foiling as the main game but I can certainly see something like this getting sales. It is similar to a two seater electric foiler I posted on another thread.

Just to move the topic on a bit.

Rick W

 

Well Chris Old Boy,

If you scroll back through this thread it's pretty clear who is responsible for most of the clutter. It is also clear from the threats of violence and your enthusiasm to carry on off list that the bully comment was right on the money.
The time you are devoting to stalking other members and spitting bile and animosity into this forum explains why your'e entire portfolio at Duckworks still says "coming soon".

 

That's more than I expected; I thought you were proposing a Moth-sized boat. I was assuming about the same weight as the crew, for one up, say 160 lb, which could easily be accommodated by a small ama: That would double the RM available from crew weight alone.

That seems odd, since the direction of the water would have to reverse. A spot on the foil strut seems more logical and simpler.

I wasn't thinking of transferring the water to the other side for tacking. Although it could be done its effectiveness would depend on the heel angle and it would be uphill when heeling to windward.

With the ama clear of the water it would run back out under gravity prior to a tack, definitely not after tacking, though! After tacking the other ama would be topped up. Probably too busy a system for racing where quick reactions are often needed but for outright speed, simply having fun or time-around -the-bouy runs against the clock, perhaps more practical.

That was clear from the start. Height of strut also would influence max heel angle.

Having watched more foiling videos, I wonder if the additional RM is the real advantage of heeling to windward. I suspect it either adds to the lateral balance of the boat or makes it easier for the crew to react to and control variations of heeling moment due to wind fluctuation and other factors. However , not having flown a foiler that is just MHO.

 

Chris, tote up the number of hours you have spent on this thread alone, stop and take a breath and then ask this question to yourself " have I contributed to this thread in a meaningful and helpful way to discuss " Veal Heel " ? If the answer is no then stop, take a breath and think of how you could have spent those hours doing a more useful task, perhaps spending time with the family, sailing, anything really thats just more useful.

Ancient Kayaker, in my opinion Veel Heel is a non runner in anything other than a Bi foil design. have a look at the best of the tri foilers such the Rave and the Hobie Tri Foiler ( and talking to owners confirm this ), all videos that I have seen show the windward foil at or about the surface. This indicates to me that the whole boat is inclining to leeward ( as you would expect in a practical way from the drag on the sails ) and for all intents and purposes the leeward foil is now inclined in a manner which is having exactly the opposite to Veel Heel ie its forces are now directed toward the leeward. Sorry Doug but it ain't going to happen in a practical way.

If you increase the RM by inclining the windward foil to get a higher angle of attack of the windward Ama then the surface drag of the foil will be higher slowing the boat rather then the benefiting ( I think the Maths will say otherwise but we have to think in a pratical way and all videos seem to show the foil at the surface where they are most inefficient ). Remember foiling at this stage of development is totally dependant on extremely light weight vessels and needing to use minimum foil ( lifting ) size to reduce the drag from the foil. Get that balance wrong and you are better off with a conventional hull.

Now ballasting the Ama may work but it is a big " may " the practicalities of ballasting whilst underway at speed and when you start to ballast are going to need the input of a dedicated crew, you maybe just better off sending the crew out on the Ama ?

Now the Bifoiler is a different beastie in particular the Moths because of their low sail area and high RM of the skipper, the foil can be inclined to weather inducing a small lift toward weather. Increase the sail area and the size of the boat and it all becomes marginal, not from a foil issue but from a physcological issue. Imagine sitting on a windward rail below the boat, it ain't half gonner be wet wild and downright scarry, increase the height of the rails to lift the ballast and you are going to have a huge effect on aerodynamics

 

That little foiler is good. Stability would be improved by slightly wider stance of fwd foils, but what the hey. It reminds me of an International Solar Class boat from (damn - can't remember the name of the US university! - anyone?) which competed in the solar boat race in Canberra in 2001 (bloody thing beat us too). It had a foiler mode, which worked if they loaded it with batteries to get it up, but it would not fly on pure solar.

I wonder if the power to weight balance might have shifted in the last 8 years, and a little foiler like that one in the youtube video might run on pure solar. If the motor is about 450w, and the prop was tuned (difficulty there - early static thrust vs foiling speed), with lightweight panels it just might work. Broad stance (beam) would be important to keep the PV array from allowing it to be blown over by a breeze though.

Here is a photo of our boat, it isn't hard to imagine foils on it, with stiffer beams. Anyone want to throw a competitor together (like - actually build one - keep both Ostlind and Lord happy!) ???

 

-I think we agree on that, but others may not.

-initially I was looking at Doug’s idea of a deployed windward foil with negative lift; you would be correct for that case.

For a boat with permanent ama-born foils both providing lift, their incidence could be changed in opposite directions to create extra RM, as Greg Ketterman suggested. Provided this differential incidence is not overdone, the extra drag from the leeward foil would be cancelled, at least partially, by reduced drag from the windward foil. *

However, once the windward foil is producing actual negative lift the total drag would increase significantly. Whether extra sail thrust could overcome that remains to be determined.

-again, I agree completely. The idea of the ballast was, in effect, to be able to pick up weight equivalent to an extra crew person once flying, with an extremely lightweight foiler that would still have the ability to fly in light airs. Unlike the differential foil incidence of Greg’s, the extra weight is going to create more drag as the foils must provide additional lift. As well as the plumbing, it might present some serious design challenges to get a foil design that can accommodate a wide range of loads. Whether it will work or be defeated by engineering or control problems remains to be seen. I don’t think I can take on the work, I am not in good enough shape for foiling!

* This is an intermediate case that is particularly interesting as it has the potential to open up foiling to the athletically challenged like me, who could adjust RM while remaining in the cockpit.

 

But you are not unique, travelling at over 20 knots does tend to give a very rough ride, I personally think that the cockpit of the Rave and TriFoiler has been derived for very good practical reasons, I'm not sure that a closed in cockpit would ding my bells though