The foil provides efficient lateral resistance and righting moment.  My aim is to get enough righting moment from the lee foil to avoid hiking out.  I want to be able to stay seated on any point of sailing.  

I tested the canting foil arrangement on the yellow pedal boat and it was quite impressive. With its tiny 4sq.m sail it could easily outpace my 10kt maximum pedal speed:

 https://1drv.ms/v/s!Aq1iAj8Yo7jNgWLyFOoBOY8T6900

That boat did not have enough reserve buoyancy to support the weight of the ply stabilisers so they are always immersed but they did not immerse much more when sailing as the foil produced righting moment.

On the 8m boat the canting foil produce enough righting moment when reaching to keep the stabiliser flying but it relied on buoyancy when pointing higher.  The straight canted foils were cambered but had zero AoA and the roll control offered when motoring was inadequate; it would just flop to on one side and stay down unless I shifted body weight.  When sailing, the leeway creates positive AoA on the lee side and negative on the ww side so the differential lift is greater under sail.  With the L-foils I have increased the righting arm and can adjust the AoA of the flat portion by raking the foil forward.  Canted T-foils would increase the righting arm even more.  I can also adjust the cant angle to get the best balance between leeway prevention and righting moment.  

On a narrow hull it makes sense to have the shaft beside the hull rather than under it.  That way the shaft is compliant and cannot be bent by beaching the boat.  If you look closely at the attached photo you will see the prop pulled way up out of the water.  The shaft is very high strength stainless and can be curved a long way before it yields.

A pedal drive mounted in a cockpit requires 1.2m from back of seat base to the forward bulkhead to give room to spin pedals.  The crankshaft is around 900mm from the back of the seat, depending on engine height.  The crankshaft needs to be 300mm off the cockpit sole to give heel clearance.   The cockpit needs to be no less than 500mm wide to ensure there is room for feet on pedals.  The back of the seat from lumbar to shoulder blades needs to rake at about 45 degrees for the most comfortable seating.  My cockpit is 1.9m long and I have room to step behind the seat. A lower height cockpit could be as short as 1.4m providing the back of the seat overhangs the cockpit. (Seating way aft on a small boat will pitch it nose up).  You can sit more upright if the seat is mounted above the cockpit sole or you are prepared to accept knee pain after pedalling for a couple of hours.  Point is you need to be certain you have the room in the cockpit to take the pedal drive.  15ft appears a lot shorter on the water than out of the water. 

I can provide parts for pedal drive if needed.  Any drawings are provided free on the basis I usually end up selling parts.  If you have the facility to fabricate stuff it is best to make as much as you can yourself and buy parts locally.  I strongly recommend T-10 belts over bike chains.  You can also get away with low cost model aircraft props if fouling with weed is not a concern.

Unless you really want the exercise and plan to go long distances, You should consider a small electric thruster and a good size LiPoly battery.  They would work out about the same cost of a pedal drive and have less space constraint.  200W battery drain on a little thruster is equivalent to about 120W human output on an efficient pedal system.  Unless you are athletic it is not easy to get much above 120W for long periods.  I expect around 4kts at that power on the little tri.  A battery having usable 400Wh, weighing 2.5kg, costs less than $300 and a 24V trolling motor also less than $300.  So good for 2 hours at 4kts.  Such a system could achieve more than 8kts with the right prop.  

Rick

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