Everglades Challenge: the Right Boat?

Sew Sew

A couple more pictures of the 2016 version-rudder T-foil(before it broke) and planing amas -much wider and different shape than earlier versions. Follows the ama development on Hydroptere that went from displacement to stepped planing amas:
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The first time I saw the Quant 23 I thought about applying the foil design to a trimaran. However, I'm beginning to wonder if balancing the trimaran on the foils would prove too difficult; in addition, after the silence following the Diam 24 foil experiments, I wonder if the additional lift provided by the foils just isn't enough to off set the drag produced by them.

I wonder if a way to optimize weight/foils on a trimaran would be to return to the lighter low volume floats and to only use the foils in moderate to heavy air; given the Diam 24 fleet's reticence to adopt J type foils on the amas.

Randy circumvented the low volume float issue simply by adding beam. The most recent photos of scissors presented with Amas half the size of the original ones. In addition, they were shaped like the planing hulls of aircraft floats, and not the smooth shapes associated with optimized light air performance.

Nevertheless, I agree the EC offers an outstanding design challenge. The beach start as well as the need for human power creates a low cost niche for handy sailors to ponder and dream. It reminds me of what the Mini 650 class was like before it exploded into what it is today.

What other race requires one to think about foils, paddles, proas and B&Bs?
In the end, I suspect the best boat would be an old carbon ARC 22 with a carbon fiber rowing station. Dreaming is always fun, but simple is it's own reward while racing.

 

Randy's boat looks a lot like the Bethwaite HSP, and now follows a similar concept. Fun boat.

 

I wouldn't draw too many conclusions about the results of the DIAM24 trimaran foil tests. The last thing the Macif team would want to do is divulge the results and give away any competitive advantage to the other Ultime teams.

 

And more...

think a second about the incremental improvement

When the quant23 gets that big fat hull out of the water drag is greatly reduced -Big improvement, and the righting lever increases a meter or so.

A performance tri already has the optimal displacement in the water at the best position, and the lifting foil is inboard so righting is actually reduced.

Lifting foils technically contribute more by being placed further off center, but the percentage improvement is less on a multihull.

The acceptance of DSS by the monohull rating regime while they continue to shun multihulls just boggles the mind. That is what makes the EC 'come one come all...' so much fun.

 

EC Foiler Tri

There would be a tremendous improvement in RM on a tri designed to use the Welbourn foils. Smaller tri's could be designed with a street legal beam and still have massive righting moment. That would simplify and lighten those boats.
Righting moment on a foiler tri* is only reduced if the ama lifting foils are surface piercing or UptiP foils. With ama T-foils or Welbourn foils, RM goes up when the main hull fly's.
The wider the tri the more it could require a lifting foil on the daggerboard to ensure light air main hull take off-- which is critical to an EC foiler design.
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The Fire Arrow uses UptiP foils on the ama and has a 22' beam. Using Welbourn foils, platform beam could be reduced by 10' overall(5' each side) for the exact same RM due to foil lift OR the Righting Arm could be increased 5' each side for the same platform beam.

*measured against the maximum RM for a given beam

 

So you are suggesting a multihull with the L foils outward rather than inward...or T. It sounds like you are just reacting to my 'reduced righting' factor as if it was an attack -it's not, I was just explaining why lifting foils 'do more' for mono performance. But let's give it consideration -the L outward has the bad pressure differential between the vertical and horizontal so at best you would make the vertical zero lift with a daggerboard in the main supplying leeway force. To be self leveling there has to be area reduction ie the tip must break the surface (or worse the horizontal breaks the surface which is very draggy). That's four surface breaks (with rudder) and a horizontal that is more draggy than the inward uptip or T. I would say that it is much easier and higher performance to just increase the aka length, face the L the right way and fly on two foils. The T in the ama has good and bad pressures unless you angle it to zero the 'mast' lift. And this is just the performance aspect -then there is cost and complexity, that's a LOT of expensive parts.

My approach would be quite different, but my goal is different. I am not looking to out fast the fast. I would use foiling to make small and cheap boats that are faster than big expensive boats. The moth style 'bicycle' foilers have the most performance for the least cost and complexity. The negative is the constant tending to stability. What if the T foil was wider and there were two wands each controlling the flaps on their side for dynamic righting? I figure I could make a boat that foils in lower wind and is easier to fly for only the cost of a second wand and only the performance cost of slightly increased wetted area.

 

Welbourn foils

Skyak, I didn't think your previous post 50 was an attack at all-I just thought the part about the placement of foils ,and their effect, was wrong.
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I'm not talking about using an outward pointing foil "L" foil on the lee side of any boat. Greg Ketterman tried that on the trifoiler and it didn't work too well. The reason it didn't work well was that the foil was being asked to lift vertically as well as help provide the lateral resistance for the boat. That meant that there would be high and low pressure on the same side of the foil which creates undue drag. The so-called "mustache" foils get around this by using the same physics as do UptiP foils but they require a substantial angle of heel to work at their best.
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What I'm talking about is using a Welbourn type foil which has a sort of "L" shape when fully immersed but when foiling almost the only portion of the foil being used is the horizontal part. The part of the foil from just above the knuckle up to the boat is designed specifically NOT to generate lateral resistance when foiling. The lateral resistance on a boat using Welbourn lifting foils for full flying is provided, on the Q23, by the keel fin and on my proposed tri by a daggerboard or centerboard. Only one foil(the lee foil) is used at a time for best performance. Altitude is controlled primarily by the proximity of the foil to the surface and exposure of the tip of the foil. The foil is designed to behave as a fully submerged foil as well as a high aspect ratio(wide) planing surface. There are pictures of the Q23, earlier in the thread(post4,page 1), showing it doing both.
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There are many considerations in adapting the Welbourn foil to a tri. And one problem that can occur is the same one than can be a problem on any wide tri: the wider the boat the more wind and/or sail area that is required to fly the main hull. So if you want to fly the main hull in light air the most effective way- without having to add too much sail area- is to use a lifting foil on the daggerboard. That means that the tri would have three foils* in the water when foiling(like almost every other multihull foiler), but the difference is that the lift required of the mainfoil(the one on the daggerboard) would change the faster the boat went because the heeling force on the rig would increase as apparent wind increased,relieving the foil of the task of lifting the main hull. That means reduced drag on the main foil. So the primary load carrying foil, as speed increases, would be the lee ama foil. The rudder T-foil would carry no more than about 20% of the load and that would change throughout the speed range until it pulls down rather than lifts up. It does this automatically.
*lee ama foil +daggerboard main foil+rudder T-foil
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Another consideration with the Welbourn foil is structural: adding the foil to the lee ama of an already wide platform will move the center of lift 5' outboard(at a minimum on the Fire Arrow) and will require another look at the engineering of the beams. However, re-engineering the beams wouldn't be required IF the platform beam was reduced so that the center of lift of the foil is about where it is now with UptiP foils. That would make the whole platform narrower but also has the effect of moving the center of buoyancy of the ama inboard-- and the effect that would have,and the size of the ama, has to be looked at as well.The reserve buoyancy provided by the ama is important in conditions where the boat is off the foils and hit by a Hand-of-God gust.
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All in all these Q23 foils offer a lot to a small trimaran designed specifically for them.

 

Okay, L ot T or whatever foil to leeward, plus usual rudder T ... and now you want another T on main hull anti-leeway dagger to early lift the main hull. How about that extra drag of the T section main hull dagger? Which will slow the boat? From drag. Which will slow liftoff. Unless you have an extreme angle of attack on said dagger T. Which will drag slow the boat too. It has been proven that too many foils are slow. It is a basic.
It's okay for you to play around with these multiple lifting foil theories on small toy models (which don't function very well anyway) - and a totally different thing to do it full size. Drag is something you don't want, needs to be balanced with lift - needs to be a minimal balance drag/lift figure. The search for the magic figure and best compromise.
And when your full size boat rocks, (from either waves or too many slow foils producing drag) the windward lift foil also ploughs through the water too. Which further slows boat.
By the way, outward facing foils work fine -as long as you're not relying on them countering leeway. This is what the latest Open 60 monohull boats use. And they have specific daggers to sail to windward. But they too are pushing defecation uphill because of way too many foils (and weight). But that is another story.

 

Foils-Fire Arrow System-with or without Welbourn foils.....

Gary, you keep saying "multiple foils" when the three foils I was referring to are the same number of foils almost every modern catamaran or trimaran full flying foiler uses.
You say the main foil creates drag but you simply ignore the fact that it is responsible for lifting the main hull completely clear of the water in light air-which would NOT happen without it. The lift it develops far outweighs the drag it produces since it 100% prevents wetted surface and wavemaking drag from the main hull.
And that's in addition to the fact that as the apparent wind increases due to boat speed the lift on the main foil reduces to zero-no induced drag.
And it has other advantages too-like providing downforce on the main foil in response to gusts. Like controlling the angle of heel of the boat. Like,with the rudder T-foil, controlling the ride angle of the lee foil and pitch of the whole boat.
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You're just dead flat wrong on this, Gary.

PS- you're also wrong about the Open 60's-the new mustache foils do develop lateral resistance for the whole boat(using the physics of UptiP foils) and because of class rules they aren't allowed to use separate daggerboards. That's why their poor upwind performance has been mentioned in just about every article about those foils on IMOCA boats.

See the daggerboards?!

 

Doug, I get all that you say above and it only reinforces my reasoning and conclusion -a wider tri with the L foils turned in will be naturally better than a narrower (or any tri for that mater) one with the L foils turned out. Personally I find it amusing are considering it when you have the superior configuration already modeled but I hope you see my reasoning.

There seem to be two things we don't agree on -1 there is some value to a tri being narrower above the waterline (still as wide below) and 2 that achieving altitude control by having the lift foil reach the surface is bad -draggy.

After reading your last post it seems to me that what you are getting at is a catamaran version of the Quant 23. NOW THAT MAKES SENSE. It could be lighter and stiffer because it has no joints. It needs to be less than 9.5 feet on the trailer but the outboard foil adds righting.

So I see where you could make a better faster quant, but I still say it naturally under performs the foiling tri you have and it gets back to an assertion I made some time back. The quant 23 has no good reason to be a scow EXCEPT that scows are accepted and rated as monohulls. Trim the fat off the brilliant! remarkable! quant scow and you have a faster, more capable boat that is a complete loser because it is a 'slow foiling catamaran'.

 

EC Foiler Tri

The main two advantages of the Welbourn foils are:
1) they work in very shallow water-more so than any other foil system that also does #2. And this is the main reason for considering them on an EC tri.
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2) they allow the center of lift of the foil to be way to lee of the boat creating tremendous righting moment in addition to vertical lift.
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The UptiP foils are probably superior to the Welbourn foils in a boat where draft is not a concern.

 

Yes, you're right about the IMOCAs and I was a year or two out of date; no daggers now. However, look at the poor design for going to windward - and that is why they've got their poor reputation. However very good lift generated with the outward facing moustaches. And there is your win and lose compromise.
Back to your proposed EC design foiler for shallow waters; you've got leeward, mainhull, rudder and windward T foils. Your windward one is going to drag in light winds, shallow water. Take it from me, the boat will rock windward foil in at times.
But deep foils will be a curse at times in this race - so they'll have to be lifted. Actually you would be better off without them in these conditions. Your lifting and flying over shallow waters is a fantasy. Look at Randy's SewSew, minimum basic work foils, planing floats and still he has trouble.
By the way, modern race foiling tris do NOT have T main hull daggers; they're just anti-leeway devices, no lift.

 

Foils

Gary, I said almost every modern multihull foiler uses three foils in the water and up to four foils total. You have repeatedly and falsely said that the Fire Arrow has more foils than any other foiler-and you ,again, are wrong-very wrong:
1) All AC 72's: one main foil retracted two rudder T foils, three foils in the water,
2) AC 45's and 50's same as 72's
3) Nacra FCS, Flying Phantom and GC32 same.
4) All legal A Class foilers 4 foils in the water,
5) Hydroptere two main foils one rudder t-foil-sailed with three foils in the water,
6) Spitfire Australian foiler 3 foils in the water,
7) Hydroptere.ch 4 foils in the water,
8) C Fly at least 4 foil pods in the water,
9) C Class foilers -all the same as #1 above,
10) The new Stiletto-just like #1 above(see the "New Catamaran Foilers " thread)
11) The S9 14' foiler cat-4 foils in the water,
12) Vampire, wand controlled main foils, one retracted three foils in the water,
13) Whisper, wand controlled main foils, 4 foils in the water,
14) Eagle, 4 foils in the water,
15) G4 same as #1 above,
16) and more I don't remember,
17) EC Foiler Tri and Fire Arrow three foils in the water, one retracted , one of the three automatically unloads as boat speeds up.

 

EC Foiler Tri

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My proposed EC foiler using Welbourn foils or UptiP foils-windward foil fully retracted.Three foils in the water:

1) main T-foil on daggerboard-unloads automatically-adds RM if desired-lifts main hull clear in a 5mph breeze,
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2) Lee ama foil-supports majority of weight when daggerboard foil unloads
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3) rudder T-foil-supports 20% of load at takeoff, automatically changes as boat speeds up.

This picture illustrates the UptiP foil version with three foils in the water in a 5 mph breeze. Note that windward foil is not dragging as you said it would Gary. And on the model the thing keeping it clear is the dihedral of the platform coupled with the designed angle of heel. On the full size version the foil would be retracted if it needed to be :