Sailing Kayak Project

One more idea to consider by taking the cross beam idea a little further. You could set up twin lightweight mast to form an A-frame mast. This link shows it is a proven concept:
http://www.sail-works.com/KOLIKA/html/kolika_20.html

You would set the masts wide enough apart at the base to allow the sail to tack or jibe without the sheet interfering with either mast. The system would require a backstay to tension the luff.

You could probably get hold of some aluminium spreader section to use as masts.

The benefit of this is that it makes the leading edge of the sail cleaner and more efficient to help with windward performance.

The disadvantage is that it eliminates any notion of roller reefing.

Rick W

 

The A-frame mast is an interesting notion for a bermudan rig but the COE height is high so a kayak couldn't handle it without floats; the outriggers would need to be longer than the boat. I can't see how to make it work with a lower rig, no way to raise a gaff or attach a sprit. It might work for the lateen but would need so far aft that I couldn't lower it for paddling. There's no space to turn around in a kayak cockpit. I would not feel safe with that much mass and windage aloft in a blow; getting back to shore always involves paddling upwind. Always!

There is a problem with the lateen sail. Bruce foils generate a moment X that cancels the sail's heeling moment Y and is supplemented by the moment Z that comes from the sail's lift and offset so that X + Z = Y. More simply, the sail force and foil vectors should cross the centerline at the same height for zero heel.

During the force vector analysis to determine the optimum outrigger length I realized that I do not know the moment arm length for Z; it is determined by the sail offset, COE height and angle to the vertical which are all variable. Note: the previous sail had a fixed angle to the vertical. For now I will make the outrigger length adjustable and look a safe best compromise during testing; if there isn't I will have to rethink the sail. I will preset the geometry to be optimum for a broad reach.

I took the boat out for a paddle last night, the water is already too chilly here for a full immersion woopsee so testing will have to wait for next Spring.

 

The A-frame mast does not need to be vertical to the beamwise axis. You can mount the foil beam as far forward as you like providing the forestay (or sail luff cord) will stop it from collapsing aft. With the foils mounted towards the bow you should be able to balance the helm reasonably well.

In fact you could have a forestay further forward than the luff of the sail.

Rick W

 

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I've tried to find old pictures I have of the system I described earlier but can't. So I'll try to describe it better:
The idea is to allow the whole crossarm/foil assembly to pivot on the CL of the boat with a small skeg aft to help directional stability. By rotating the assembly you can:
1) steer the boat
2) adjust the foils for their most advantageous AOA upwind and downwind.
It combines the function of the rudder with an adjustable foil angle. Its actually quite simple requiring only a strong pivot point to attach the assembly to the boat and does not require any special arrangement with the rig. The system would be set up so that the leeward foil lifts vertically and the windward foil pulls down while both contribute to lateral resistance.
I hope this is a bit clearer-anyway it does work.....

 

Rick: here are my updated thoughts. With a lateen the clew has to fasten at the bow to keep the COE forward. With an A-frame mast its base must be aft to clear the tack, the best place for access (assembly/disassembly) would be just aft of the cockpit, which restricts the allowable length of the sail foot and hence the area. I could take a backstay to the stern; for paddling I could drop the mast forward with its legs either side of the cockpit. That would interfere with paddling so I would then have to dismantle it, but I intend to do that anyway.

The foils will need to be positioned aft of the CoE to balance the rudder moment. The cockpit is slightly aft of midships. Putting all that together, For adequate sail area the foils mount just ahead of the cockpit, and the sail COE should probably be a little forward of the CoG which is within the cockpit. I will take a serious look at it but I’m not yet sold on the A-frame’s advantages.

Doug: now I understand; rotating the foil assembly for steering is ingenious. Pivoting the hull close to midships may improve agility. Perhaps the fixed skeg can be on the bow so it can be mounted on the same frame as the outriggers, if that doesn't mess up the balance. Main problem I can see is getting enough of an angle for nimble turning without mechanical interference with the hull etc. and without the complexity of an Akerman linkage or the pantograph arrangement I had on the earlier effort, but I will give it serious consideration.

Usually kayaks are steered with the feet as the hands are busy paddling, not so much when sailing and hand steering would be easy to arrange with rotating foils. I think the Hobie sailing kayak is hand-steered.

The foils will be asymmetrical, each optimized for one tack, so adjusting AOA for upwind will require very small changes to one foil relative to the other. For downwind I am less concerned for efficiency and can lift the foils.

Allowing the foils to pivot so one lifts out of the water requires another axis of rotation with consequent increase in complexity. I’m not sure if that’s what you meant. I can design the foils so they can be lifted independently, pivoting the outriggers would do that, then I can test to see if that improves performance any.

It's looking good! I think it’s time to sharpen a computer and get on with the design.

 

Doug: having forgotten my medication last night I woke up with a strange thought. If I take your pivoting/steering foil assembly concept a little further, and pivot the mast/yard at the same time, tacking can be achieved virtually instantaneously without loss of the upwind component of velocity.

It merely involves moving the pivot location, currently between the crossarm and base frame, so it's between the hull and frame.

It's may be hard to visualize so I have attached a sketch. The aft skeg pulls the hull into line and since the kayak hull skids sideways easily it would not generate too much drag during the turn.

There may be a problem when sailing on a reach, with the wind abeam the hull may yaw but the skeg should resist that tendency once speed builds up, and I can balance it by adjusting the fore/aft location of the rig on the hull.

This seems like an idea that should have cropped up before, but it is only practical on a really small sailboat with a lateen sail or moving bowsprit (so the clew moves upwind). Also it is only needed on long skinny boats that are slow to turn. Hmm, like a kayak ...

 

Cool! Give it a shot-looks like it would work.....

 

I am finalizing the detail design. I started several other threads to explore issues such as foil profile and hull shape, but I will continue to report progress on this thread.

Here are some freehand sketches of what I think it will look like with the lateen sail - I don't have a 3D graphics application so forgive the perspective errors. I have replaced the small floats that I deleted earlier since they serve to conveniently attach the foils to the booms. I am also contemplating a version with a wing sail in the 10-20 sq ft range to replace the sprit, spar and sail, but first things first.

The first pic shows the boat on the port tack prior to coming about.

In the second the pivoted Bruce foils and sail assembly have been rotated and are already on the starboard tack; the hull will be brought onto the new heading by the fixed skeg at the stern.

Dimensions for the rig shown are: 10 ft yard at 45 deg mounted on 3 ft sprit and carrying a 25 sq ft area lateen sail, 2 Bruce foils 1.5 sq ft each inclined inwards at 45 deg and mounted on 3.5 ft booms, turntable 8 inches diameter.

Construction will be aluminum tubing and plywood using "anybody can do this" techniques. The sail will be cut from a tarp, it must shed water because it will get dunked when it is raised and lowered, It can be taken down and the 3-piece yard can be dismantled from the cockpit, hopefully these can be stored on the foredeck. Foil booms are telescopic and can be retracted from the cockpit, Foils and floats can be rotated forward to rest on the foredeck, which is going to be a bit crowded when the boat is rigged for paddling.

 

I'm sleepy, skipped the last posts. I feel you might be better served with a truer hapa. It doesn't neceserily have to be on strings, could be on a boom, swinging around behind, or in front of, or over, the hull. it would always be to windward and you would attach it to the hull and to the yard to create a triangle that will keep you upright as long as the hapa is submerged and there is wind in the sail. there is a swedish speedsailing boat using this principle. I think a shunting hapa on two strings may be the simplest. It would provide its own surface tracking and would be unaffected by your roll angle. Someone made a yellow one in scotland and I think the pics were in the proa file yahoo group. that was an uber simple affair with no moving parts IIRC. Kun Fett was my variant of the concept, there are some pics and vids here but it had too little area for such a task, it was more to see how a lightweight overpowered hapa could be made to behave (like a dragonfly on amphetamine).

Somewhere on the web there was a red model tri with canoe like bows. It had curved foils on little booms, which were pivoting up and down from the ama so that if the ama rose the downforce from the foil would increase.
As I understand it you are using the lee foil for righting moment since the ww foil is not made for dynamic downforce, so you are more like a normal tri without the ama bouyancy. Windjet (I think) and Jon Howes monofoil are other boats that illustrate the no heeling thing, which is not what you are doing - you can see that they are using low aspect but also a wide base, which is easier to get with strings to the hapa.

PS. If you make a shunting hapa you should try out Tom Speer's P3xxxx sections.

 

I haven’t encountered the term HAPA before but I think it’s a hydro-kite for reacting sail force, performing the same function as the Bruce foils in my concept. The Bruce foils, being rigidly attached and rotatable, can be used for steering, not sure if I can do that with the Hapa on lines. Previously I used a single flat Bruce foil with an inclined sail and there was negligible rolling and I am not anticipating any such problems with this design.

With the single foil I got virtually zero heel but I found it was more effective on the lee side and when it became immersed due to imminent failure of the outrigger it continued to resist heeling. It was less consistent on the windward side, although it never lifted out of the water. Therefore I plan to use 2 foils this time with asymmetrical profiles with alphas set so the lee foil will provide lift to offset heeling while the weather foil will coast at minimum lift/drag alpha hopefully. The lee foil lift should also reduce or eliminate leeway which was a problem with the previous system.

I started this thread to look at a shunter- http://www.boatdesign.net/forums/boat-design/hydrofoil-profile-question-24677.html -and Tom provided data on P-30208 but I decided against the shunter. I will probably use Clark-Y. There are probably more efficient hydrofoil profiles and Tom suggested it was too thick, but it is fairly tolerant of errors and predictable. I will reduce the thickness to about 85% - strong enough given the available material (softwood). Clark Y thickness is about 11.5% of chord so 85% would reduce that to about 10%.

 

Ofcourse, a heel-less rig can mean a rig that does not heel - as you have made.
However what I think of in connection with it, and with bruce foils, is a rig where ballast is not the primary reason for not heeling. To be pedantic I would say that you are not using the bruce foil (it is coasting) but your zero buoyancy leeward trimaran ama has a canted daggerboard. If stability is not an issue then why do you not put up more sail and be able to sail to windward? To me your configuration looks stability and or area challenged, so here are some other ways to get it.

In my definition of heel-less rigs (for the purpose of this message), the hydrofoil has to be on the windward side of the sail, and its downforce must increase inversely proportional to the lateral distance between them.
It will be useful to allow the hydrofoil to increase downforce when it is in danger of leaving the water. Several ways to do that.
Here is Robert Biegler's paper, includes the scottish (?) hapa I mentioned, and some theory and some other stabilising configurations. I think he tries to explain why your bruce foil did not work:
http://f1.grp.yahoofs.com/v1/4EWBSa...BiBwZydkmH_cWE0tebBs4/Robert Biegler/Proa.pdf

ps. the hapas can be flipping or tacking or shunting.

 

Another way of making the kajak heel-less, is to displace the rig from the kajak laterally, and use the kajak as a big hapa. Most easy if you use an air kite. Peter Lynn devised a way to ensure that an imaginary extension of the kitelines passed through the CoE of a normal daggerboard, without using akas or amas. You can find it at www.peterlynnkites.com, under the news section, a year or two back I think.
For this, one could use either the Peter Lynn Arc type, or a bridled foil with closed leading edge, like Flysurfers, so that you don't have to pump the kite. A Leading Edge Inflateable may or may not be easier to launch. In this size a big stunt kite with spars may also be viable.

EDIT: Mal Smith's proposals for heel-less-ness. Not exactly directly transferrable to a kajak, though some parts may be. http://www.members.optusnet.com.au/mal.smith1/Vproa.html

 

Bernard Smith's fliptacker rigs may well be suited to a kajak. They go something like this drawing, and this link here is the same but different: http://f1.grp.yahoofs.com/v1/AGKBSS...WVZ52PX3AOmU/Fliptacker and proa/Fliptack.gif

EDIT: And here is the tri, and a lot of other nice craft.
http://www.geocities.com/aerohydro/othercrafttext2.htm

EDIT: and here are Ashford's Sea Dog hapas: http://f1.grp.yahoofs.com/v1/QJqBSf...OS1M4JX/Biegler/Ashford anchor dog 2006 a.jpg

 

AK your concept is fun to contemplate. You must be a lot younger than I am because you are still fascinated with avante garde stuff. It seems, that you are committed to the Kayak planform. OK! I like 'em too. I also would like to sail my Kayak, but I do not have the urge to build something that is a pain in the *** to rig and operate. Chris O has made useful comments.

Perusing a book by Tom Firth Jones, I happened upon his Tuckakoe 10 design and build. It is a too short 10'3" X 36" sailboat that can easily be propelled with a double paddle. The Tuckahoe uses 45 square feet of sail. It is by Jones account somewhat tender but entirely manageable. I have thought rather seriously about stretching the design to 15 feet or so. Now we have a boat that will go well, paddle decently, and can be rigged/unrigged in 60 seconds. Such a boat could be built with a weight of under 50 pounds using Jones method. I will bet a chicken dinner (if I can find a convenient feed store) That your foiler will be a lot heavier, need a gob of hardware, and will not likely go any quicker than the conventional Jones boat.

Your refutation is politely anticipated.

 

Sigurd: you are correct, technically the foils are mounted on amas but they are very small and buoyancy only a few pounds, they are primarily to provide a neat interface with the outrigger which is an aluminum tube. The extra stability will be handy during rigging but I plan to keep them out of the water while sailing. With foils on both sides, using the leeward foil to counteract heeling results in the foils being toed-in which also provides some lift; I hope this will result in less drag.

The principle of the Hapas and Bruce Foils are similar in that the force vectors of the hydrofoils and sails must intersect at the centerline for zero heeling moment. While a Hapa can be deployed further out at a lower cant angle and should be more efficient, it must be to windward so it would have to change sides to change tacks.

I could not access Robert Biegler's paper but I enjoyed the Peter Lynn offerings! Bernard Smith's fliptacker rigs came up in another of my threads http://www.boatdesign.net/forums/sailboats/highly-assymetrical-wing-sail-25362.html and is something I want to try out later; I am still working on the rig and wing design.

Messabout: unless you fought in WW1 I doubt I am much younger than you at 69, but thanks for the compliment! It was a compliment, wasn’t it, not a stab at my juvenile tendencies? I like the simplicity of kayaks and the sheer idiocy of trying to make one into a sailboat appeals to me as something to do in my declining years. Your comments on ***-pain rigs were noted with interest and my refutation duly follows.

My last sailing rig could be rigged or unrigged from the cockpit in 30 seconds. It was utterly stable to sail even when, on one occasion, it was starting to fall apart. I never weighed it but it was around 7 lb including the rudder. Of course it was only a 15 sq ft sail, but very lo-tech, doweling mast, ply foils and decks and tarp sail. Maybe $20. I had a plan to up it to 25 sq ft but it was destroyed in a fire.

The new rig will be heavier certainly, around 20lb I estimate, for 25 sq ft, mostly Aluminum, and not as quick to rig/unrig, but it is really just to explore a few new (to me) concepts. I am planning to put it on my plastic kayak which is a bathtub-shaped 50 lb slug. I would like to try the rig on a new 16 lb canoe that I am just finishing, or my previous canoe which is durn fast. If the idea(s) works then sometime in the future I might make a special purpose hull for a flip-tacker, lighter, and with performance in mind, maybe even a foiler when/if my health is up to the challenge of sailing it. In the meantime, I will toast you the next time I have a chicken dinner!

The Tuckakoe 10 sounds like an interesting design and 45 sq ft is quite a lot for a boat of that size. Me in a kayak is a combination limited by inability to hike out so I haven’t tried anything like that much sail yet but ...