Taking Off the Training Wheels (Sailing a Hydrofoil Trimaran Without the Amas)

[Doug Halsey]

In an earlier thread (Ama Hull Shapes - 5/29/08), Gary Baigent made the comment
If I had more courage I would build a foiler without any floats at all, just large foils. Whoops!!!

This inspired me to try to sail my hydrofoil trimaran (Broomstick) without its amas (floats). In my case, I didn't have to build or modify anything; the amas that I use in foiling mode simply attach to the crossbeams with bungee cord.

My plan was to go out on a fairly moderate day, first with the amas attached to make sure everything was set right & working OK, then come ashore & ditch the amas. This plan quickly fell apart when I ran into a giant kelp bed (or some kind of weed anyway) & had to spend several minutes in all sorts of odd positions to remove all the weed. Thank goodness for the amas, that time!

Next time out (6/11/08), I launched farther down the beach & was more aware of where the patches of weeds were lurking. I sailed for a few minutes with the amas, then got up my nerve to take them off.

There were some awkward moments (Photo #1), but as soon as the boat had any forward motion at all, it was surprisingly easy to sail. In one sense, it was much easier to sail. When it's not up on the foils, Broomstick's crossbeams don't have a lot of clearance & it only takes a small amount of heel for them to to hit the water, causing tremendous drag & risk of a slow-motion capsize. Without the amas, it seemed to be much easier to keep this from happening. Apparently, the extra drag of the leeward ama when it is deeply immersed is a more powerful factor than the extra righting moment that it provides.

The boat also seemed to perform better & felt more lively. For the first time ever, I was able to take off while close-hauled at about 50 degrees. (Previously, I might have flown that close to the wind, but I did it by reaching off first until foilbourne). I would have expected a smaller improvement, since I'm only eliminating 20 lbs of weight (out of about 200 total, not counting my weight) and also a small amount of windage. Obviously, I can't quantify this very well, but I was very pleased with the performance. See Photos #2 & #3. Top speed for the day was 20.2 knots, in a fairly moderate wind (low to middle teens).

I did let my guard down one time & capsized, for only the second time ever ( Photo #4). That didn't really dampen my spirits much, since I was able to right it without help. I definitely plan to sail without the amas much more.

One final question - If I'm sailing without amas, can I still call it a hydrofoil trimaran?

Note : All photos were taken by Terry Curtiss.

[Chris Ostlind]

Who was the idiot who said we get more timid as we grow older?

Very interesting development and now begging for even more design mods, such as a bit more aka clearance and that will most likely necessitate longer foils. Sorry I mentioned it.

This success probably confines the boat to warm water/weather sailing, as it will be no fun at all trying to right that puppy in truly cold water. Still, it's probably a hoot to take the risks with the boat and make these discoveries.

Does the gustiness potential there make for a higher premium on athleticism while trying to keep her upright at the start?

Nice stuff, Doug.

Hey, I'll be out in SoCal for two weeks starting next Wednesday. Maybe I can swing by your place to check out your boat?

My regular email is: Chris at Wedgesail dot com drop me a line with your number and I'll shoot you a call.

Chris

[Doug Lord]

Congratulations,Doug! Very cool.

[Doug Halsey]

Chris & Doug:

Thanks for the interest & the compliments. This project has probably been the most fun of any I've been involved in, and it's gratifying when someone else takes notice.

Chris: Addressing each of your points:
Who was the idiot who said we get more timid as we grow older?

You must have found out that I used to race Moths in the 1960's.

Very interesting development and now begging for even more design mods, such as a bit more aka clearance and that will most likely necessitate longer foils. Sorry I mentioned it.

Longer foils would definitely give me more headaches! One of my biggest problems has been keeping the foil brackets attached to the crossbeams. Sometimes I think that the best solution might be to run the foils through wells in the amas (like on Gary Baigent's Flash Harry) to give them something more substantial to bear against. Of course, then I couldn't use vee-foils & I couldn't sail without the amas.

This success probably confines the boat to warm water/weather sailing, as it will be no fun at all trying to right that puppy in truly cold water.

Since it only takes a minute or two to attach or remove the amas, I can have them on the beach & decide at the last instant whether the conditions are such that I feel like I need them. For now, I'll probably use the amas if the wind is over about 18-20 knots, or if I'll be measuring the wind, taking many notes, etc. As I get more used to it, I'll no doubt sail more often without them.

Also, this capsize happened in such slow motion that I never fell into the water. See the attached photo. The other time I capsized was in the middle of November, 2005 & it was plenty cold (at least by California standards). Still, I usually only sail from May through October.

Does the gustiness potential there make for a higher premium on athleticism while trying to keep her upright at the start?

I don't consider this to be very athletic - not nearly as much as the 1960-era Moths or the 1970-era Windsurfers I used to sail (even factoring in my ages, then & now).

Hey, I'll be out in SoCal for two weeks starting next Wednesday. Maybe I can swing by your place to check out your boat?

I'd love to have you see (& possibly sail) the boat. I'll be emailing you shortly to try to sort out how, when & where to meet.

[Gary Baigent]

Fanbloodytastic Doug, you're a better man than I am Gungha Din.
Actually the British 1988 AC challenge Blue Arrow, although apparently it tipped in deep on a sea delivery trip, (I heard a rumour that it actually inverted, anyone have more knowledge?) had an interesting float/foil configuration: the foil thickened as it rose above the (usual?) waterline, a bit like an upside down bottle - crude description but you get the image, and in flat water the boat looked fast and stable in photographs to me. Blue Arrow was designed by a group with Ed Dubois, Adrian Thompson, Barry Noble and other British hotshots - definitely breaking new ground. Hey you blokes, tell us more about it - doesn't matter that it was considered a dismal failure, there are plenty of us out here who want to know.
Another pioneer was kiwi Noel Fuller who had triangular float foils that thickened above the water on his 14 foot Sabrina - those foils worked well, didn't bury but Sabrina was not a good windward performer - but reached along impressively enveloped in spray with the doughty bearded designer hidden from sight by a curtain of white.

[Doug Lord]

Heres more:
http://www.policesailing.org.uk/reports/nimss/americas.htm

[Doug Halsey]

Gary & Doug:

Thanks for bringing Blue Arrow to my attention. How could I have been unaware of such a neat boat?

There have actually been quite a few foilers that were essentially trimarans without amas (I repeat, can we still call them trimarans?). A well-known one was Don Nigg's Flying Fish (featured in some of the old hydrofoil books).

One of my favorites was Gary Seaman's flying drainpipe (see photo). This boat won a speed-trial at Hurricane Gulch, CA in about 1972, beating the notable D-Cat Beowulf. The wind was fairly light & the winning speed was only in the high teens. As I recall, he really struggled in stronger winds. It must have been a real bear to sail (unlike Broomstick, which is actually quite easy, even without the amas).

[Doug Lord]

Gary & Doug:

I repeat, can we still call them trimarans?.
----------------
Interesting question-one that was wrestled with in the Moth class. They finally decided(rightly or wrongly) that foils mounted off the center line were a "multihull" configuration. If we go with that definition then what about Kotaro Horiuchi's boat? It seems that maybe we'd have to make a judgement about the size of the buoyancy at the end of the "racks"?
Kotaro's boat is "obviously" a trimaran but the Bladerider "obviously" has buoyancy pods.

[Doug Lord]

Check these out: (from scuttlebutt via SA)

[ancient kayaker]

Interesting to note your experience without the amas, Doug (H). My first venture into sailing, apart from the odd rented or borrowed boat, was a sailing canoe with a single home-designed and built ama. I was careful to keep the ama wet at all times assuming that was the thing to do, and was consistently disappointed with the pedestrian performance.

Then one day I found myself tearing along in a modest breeze. I looked around to better judge the speed and Lo! There was the ama a foot out of the water! It was my introduction into just how much drag a short and badly-designed displacement ama could create.

No, I haven't tried foiling yet, but ...

[Gary Baigent]

Well, as I posted before Doug, you're a better man than i am - however recently I took Flash Harry out in an informal (but as usual serious) race with winds gusts to over 25 knots and good sized, solid waves running, full sail and wing on Harry (can't reef, no points .... will be changed) and the bastard buried foil and float and half the main beam, never happened before. Also the loads were so high one of the foils started spitting its carbon off during continuous flying, then crashing, didn't break but looked very secondhand when removed later. So making a few changes on Harry, going to inverted Y foils to reduce the bloody crashing, keeping the floats, sorry, empirical knowledge overpowering pitiful attempts at valour, full width main sheet track (to better control a completely overpowered sail and rig) and various other improvements.

[Doug Lord]

Gary, what do you think causes the crashing?

[Gary Baigent]

Hi Doug, large waves and Harry flying off the tops of them, foils completely out of the water, or almost clear, ventilation, roaring, crash, immediately leaps up again, accelerates tremendously, crash, enormous deceleration, repeat, fun but you just know if you could stay flying ... lot better fun. Foils are surface piercers, (like small Hydroptere) inverted T's or Y's are better IMO - I've fitted them to G. Marx and I really like them, greater lift, less ventilation and require less surface area too. I had to reduce them because I had too much lift and the platform (which has some dihedral) would begin to rock - but now it is steady. In flatter water the originals are fine too, just larger waves cause the problems.

[Doug Lord]

Gary, thanks for the info! Good luck in the fix...

[Gary Baigent]

Forgot to mention - Inverted T rudder saved my bacon, kept stern down, otherwise I'd have gone helicoptering horizon sudden climb, pause, silence, blue wave swept sea suddenly above head, lots of bubbles.

[ancient kayaker]

Is that the good old "down the mine" syndrome or the standard involuntary highspeed baptism?

[Seafarer24]

Why don't you just strap the amas on TOP of the crossbeams? For that matter, some sort of inflatable float would do as well.

That way you can't entirely capsize if you screw up, but they're out of the way otherwise.

[Doug Lord]

Heres a video of Dr. Bradfields NF3 foiling with no amas(to speak of):

http://www.youtube.com/watch?v=oRUewjLbi_I&feature=fvsr

[Busman1965]

The video of NF3 with no ama's was a very early one, when she was first built. That system proved to be very poor, and unmanagable in many conditions. Acutally we broke the main crossbeam by burying the outboard end, after a ventilation crash.

Some long cylinder type floats were tried next, but they were a flop.
We later refitted a a pair of surfboards to the ends of the cross beams, which worked very well. They had just enough bouyancy to prevent burying, and skimmed smoothly in calm water.

The trick is to keep the dihedral of the cross beam high enough, so that the boat does not rest on both ama floats at the same time. This allows you to sail with both ama's clear of the water, when hullborne, and keep the windward foil out of the water, when it is retracted.

Nf3 liked to be sailed with the leeward ama about 6" off the water, so the foil hinge was above the waters surface.

Having sailed without amas, I cant recommend it. It is too easy to bury the leeward crossbeam, when taking off. Falling to windward in a lull is also an issue. Also, the dreaded ventilation crash can become much more dangerous, with no bouyancy on the tips.

Hydrofoils are touchy enough to sail, that they really need a little extra help from amas, just to remove that issue from the mind of the poor devil sailing the thing.

[dacarls]

Hi Busman,

I actually saw this boat on its trailer when Tom and Sam were first selling the converted Hobie16 foiler. My friend Hollis actually bought one, then traded it in on a new Rave.

[Busman1965]

I actually bought NF3 in 1990 from Sam Bradfield. I sailed/raced it for 5 years or so, and then donated it to Chapmans School. Some one else bought it, and then abandonded it later on. Tom and Sam were able to get it back. You probably saw it after all that happened, as that was when the Hobie 16 conversions were going on.

I sailed the Hobie conversion a few times, and thought it was pretty neat,for a cheap little hyrofoil conversion !! Also it was a heck of a lot easier to rig than NF3(that wing was a real SOB).

I thought about buying one of the Hobie conversions, but by that time, I was Hydrofoiled out, after 8 years and 6 different foiler boats. So I bought a gaff rigged catboat instead!!

[dacarls]

I talked to Randy Smyth about this boat 3 weeks ago- he sailed it in the 18 M2
Nationals with its J-foils.
Too bad it wasn't built light.

[Busman1965]

Yes, Randy did sail with us a number of times on Nf3 and some of the later foilers we built (Hydrosail 21, Mosquito, etc). Alot of good sailors came to try out the various boats, to see what foilers were about. You have to remeber, this was in the late 80's, and we were about the only foil nuts around, at the time. Some left very impressed, others indifferent, which sort of mirrors the public sentiment about foilers in general.

At one point we has 6 different foilers at our site, so we had alot of variety to play with!!

NF3 was not really too heavy a boat, her big hinderance was the J-foils were not built for flat out speed record attemps. They were designed for "round the Bouys" racing. As such, they were profiled to produce better speeds in semi-hull bourn mode. The theoretical top end of these foils was 35 knots, but in practice we found that they could be pushed well over 45knots, by reducing the angle of attack, using the rudder foil's trim tab, and decreasing the horizontal lift angle of the J-foils. We had alot of runs in the high 40's in those days, which was pretty good.

Our later boat, the Hydrosail 21 used one of Randy Smyth's old World 1000 catamaran rig. That boat was a really nice steady performer, and did well in races. It was alot harder boat to sail than NF3, as the crewman had to be in 10 places at one time, as well as being windard ballast!

I am sure NF3 could have easily been a world record boat, with the right foils.
The rigid wing sail developed far more power than the foil system was able to dissapate. As a result, we had to sail her on the conservative side, or she would break foils, crossbeams, etc.

I believe I have the honor of being the first person to pitchpole a sailing hydrofoil, at speed. We were always under the impression that the rudder foil would prevent a pitchpole, when it went to a negative angle of attack. I proved this to be false, by pitchpoling NF3 in clam water with a 15knt wind.
This was not a fluke, as I had it happen on 3 different occasions, while I owned NF3.

[Gary Baigent]

hey Busman, that is very, very interesting. I remember looking at photographs of NF3, with the full wing and J foils, and being very impressed - you blokes were pushing the boundaries - but what I didn't know, was that you achieved those very high speeds, although I knew the boat had to be fast. On the point of pitchpoling, I've buried Flash Harry many times, and once recently right over the main beam, but the inverted T rudder saved my bacon everytime. What did you do, in only 15 knots wind, to achieve this momentous record?

[Busman1965]

NF3 could really develop some serious power in 12-15 knots of wind. With the camber induced wing, set with a fair amount of camber, and a slight twist off the top, she could really move in medium winds. As I said, the wing made alot more power than the boat could handle. We could get 2.5x wind speed under the right conditions.

My first pitchpole was the result of a ventilation crash, when I was hotdogging on a lake in West Palm Beach, one day. The foils ventilated, and the bow dropped pretty fast, as I had the j-foils set in fairly vertical position (less lift, more speed). Since the foils were more vertical, the recovery of lift was slow, and allowed the bow to get under water . Nf3's bow was very short,only3ft in front of the crossbeam.

Once the bow submerged, the stern kept going up and over, and catapluted me out of the cockpit, into the wing sail. I came out of the wing sail cut to ribbons by all the carbon fiber and epoxy !!!

I was able to duplicate this feat, 2 more times over the years, but with a cockpit seatbelt, I stayed out of the wing sail....a big plus!!

I have a beauty of a scar down my right leg, from the first pitchpole, which is trophy from that ,ahem, momentous event.

We learned alot of lessons the hard way, that hopefully helped the breed evolve.

I do find it interesting that Hydro Petre looks like a giant version of the Hydrosail 21, even the design of the crossbeam and the foil control system.
I would have thought that 20 years would have brought more changes than it did!!

Thanks
Don Carson

[Doug Lord]

Don, very interesting stuff-thanks! Have you seen the new Osprey? Seems like it will be a sort of carbon Rave... Last I talked to Dr. Sam (2 months ago?)
he said they were about "20% along".

[Busman1965]

I have not seen the Osprey yet, but knowing Sam, it will be very interesting and well thought out. He has been at it longer than anyone else, truly the father of the modern sailing hydrofoil!

It was the high point of my sailing life to work for him, and be a part in building 4 hydrofoil boats. We had alot of fun,even when everything fell apart! Heck, in one race,we finished in 1st place,foilborne, and settled down on the hull after crossing the line, and promptly sank!!! We had split the hull stem to stern, smashing a wavetop on the final leg of the race. Since we were on the foils, we did not know about it till the race was over.
Fun times....

[Gary Baigent]

Don, could you post some photographs of that important, historical time. cheers.

[Busman1965]

I have to look around for my old photos of my time with Dr. Bradfield. I know I have complete building photos of the Hydrosail 21, from the bare hull to sailing. Also, alot of photos of NF3 under sail. I think there are some shots of Mosquito (an 18sq Nacra hull based foiler), and a few other boats that were around at the time. It was a very intersting time for me, as I felt like we were really pushing the envelope of performance.

[Doug Halsey]

Don :

Like Gary, I've always been tremendously impressed by NF3. Not only was it a technological marvel, but it's possibly the most beautiful foiler I've ever seen photos of.

I wonder if you have any numbers for the depth of the aft foil, compared to the main foils ? One mistake I made in designing Broomstick's foils was to put the aft foil too shallow. (In my defence, I didn't really "design" it that way, I simply slapped a foil on the bottom of an existing kick-up rudder. My real error was in using the same aft-foil depth when I made a second, more substantial rudder.)

When the boat is flying on the tips of its foils, the aft foil can get too close to the surface & possibly stall or otherwise misbehave. I've never pitchpoled, but I've seen some pretty wierd effects (like the fountain in my wake in the attached photo), & I firmly believe that this is a major factor limiting Broomstick's top speed so far.

[Busman1965]

If my memory serves me right, the rudder foil was 4ft, when fully extended for flight. The rudder foil was made of some old Harken Sailboard Foil Extrusion.
It was not a kick up rudder, but rather a dagger type, that retracted vertically. A pin was inserted when fully extended, to lock it in position.

Since the rudder foil was a fairly thin foil section, it was easy to stall at low speed. The flap on the foil was controlled by a small push pull cable, in the cockpit.

The rudder foil was deeper than the main foils by about 6". In practice, it worked out well, as it did not ventilate. We had a bright orange stripe on the main foils, which was the danger zone. If you could see the stripe above the water, you were about to ventilate. That usually ment giving the rudder foil some more lift, to change the angle of attack downward on the main foils, decreasing the lift. Also, we found that falling off the wind a couple of degrees would cause the boat to settle lower on the foils,which was handy in puffy conditions.

The fountain off the foil was something we saw at times,also some great roostertails,at times. Alot of it was the rudder to foil joint, and the foil ends.
Both areas need careful fairing and smoothing.

I still have 2 sets of J-foils from NF3,in my warehouse. I will dig them out and post some pictures of them.

[Doug Lord]

I was able to duplicate this feat, 2 more times over the years, but with a cockpit seatbelt, I stayed out of the wing sail....a big plus!!

Thanks
Don Carson
======================
Don, I've been thinking about this since you posted it for possible application on a couple of my boats down the line. If your rig had broken what was your "quick way out" plan? Any thoughts on your system would be much appreciated...

[Busman1965]

Doug,

Since NF3 was operated from a seated position, with foot steering, I was able to utilize a lap belt bolted to the floor. I sewed 2 loops in some 1" nylon webbing and used a harken snap-shackle as the buckle.

I had a large, orange monkeys fist knot on the release,to make it easy to find underwater.

I left the belt slightly loose fitting, as its only function was to keep me from flying out, during a pitchpole.

As a final exit strategy, I had a Swedish "Mora" sheathknife velcored on the belt. The "Mora" is the sharpest rigging/survival knife I have found......it has saved my hide on a number of occasions!!! And they are CHEAP!

The belt did work, as I pitchpoled with it, and I DID NOT fly into the wingsail.

[Doug Lord]

Thanks, Don. Would you use it again?

[Busman1965]

I would! There are so many variables in foil boats which can cause a crash,
a little safety is a good thing. I am a walking monument to various crashes
sustained while foiling.

All of the foilers after NF3 were trampoline type boats, which precluded using a safety harness or belt.

I received some serious thrashings on these boats.
Wrenched neck, broken ribs, puncture wounds on my legs,were just some of the fun adventures.

[Doug Halsey]

Don,

I'm more worried about safety then I was the first couple of years with Broomstick. Last summer, I got thrown off the trampoline twice & turtled both times. In the photo shown (when I broke a foil), I didn't hit anything on the way over the forward crossbeam, but the other time I gashed my hand pretty badly on something (probably the stay).

I've thought about some sort of strap to help keep me in place, but so far have shied away from that for fear of getting tangled.

[Gary Baigent]

I've done my share of crashes and juddering stops but have never been catapulted off ... and that is because my tiller is well aft, and gripping that helps stop you flying forward, but most importantly, I'm also gripping the main or traveller sheet which is behind me, ALL the time ... and that's a good safety harness.
Years ago on Supplejack cat, coming back singlehanded from Kawau in a strong north easterly, again using only the wing mast (and travelling bloody fast passing numbers of fully crewed keelers running for home) we all got into a wind against tide waves over a deep shoal out from A Buoy ... and the half dozen keelers beside me all broached on a large and ugly shaped, breaking wave - while Supplejack went up to what seemed almost vertical on her side, completely burying her leeward hull under white water, me with the helm hard up trying to turn downwave and my other hand gripping a bit of hatch cover rope ... which without I would have been to leeward in a flash with the boat going over on top of me. So a bit of rope in one hand could probably save you guys with foot or wheel steering. I don't like the idea of tethering yourself to a multihull.

[Doug Lord]

I don't like the idea of being "tethered" but maybe it's worth thinking about. On boats like the Moth with shrouds some guys have been really hurt flying into the wires. Dons experience is enlightening but I'm still not convinced-on my boat one will sit on a seat with feet down in the cockpit(or in a single seat in the center)-and the flying version will have shrouds.....

[Busman1965]

I agree that it is not good to be teathered to a multihull, in principal. But when dealing with the excessive speeds and rapid stops a foiler can generate, it may be the lesser of the evils? My personal feeling was it was right for NF3, however, on other foilers I have sailed, it was not possible or desireable to do.

The idea of holding the tiller and mainsheet is very valid, it will keep you from flying, but on NF3 the rudder was foot controlled, and the main sheet was ahead of the helm position, so that was of no use.

I remember thinking during the first pitchpole, as I flew out of the cockpit into the rigid wing...I should of had a seat belt.

On soft sail foilers, the potential damage is about the same as a fast catamaran, so it is an acceptable risk, but there is the issue of hitting the foils themselves. I calved a good hunk off my shin, on the rudder foil of Mosquito when a strut failed, and the leeward foil folded (don't ask me how it happened, it was a blur...).

The single best safety device was a good thick wetsuit, and knee pads. I know this saved me from many injuries during crashes. But, it will not prevent broken ribs......I know this first hand!!

It's funny, I still have little chunks of glass and carbon fiber come to the surface of my scars, from my first pitchpole. Every now and then, I will see a little black fleck in one, and have to dig it out. Amazing,as it happened almost 20 years ago!!!