Join Date: Jan 2011
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Re: Last one for tonight. Tiller pilots
There are a lot of factors to consider and the manufactures cannot properly explain the engineering, so they simplify the solution to just specify the weight of the boat. If you look into details, there's more than that.
Tiller pilots are limited in their power, which in the truest engineering sense is a product of force and speed (power = speed x force). The manner in which you mount the tiller pilot determines your trade off for force versus speed. Mount it close to the hinge point (pinion) and you will get a lot of speed in the turning action. Mount it far from the pinion and you'll get a lot of force.
Fin keel boats with spade rudders are flighty and don't like going in a straight line. The pilot will have to do a lot of work and fast response is going to be helpful.
Balanced rudders have little feedback and need little force for steering. Unbalanced rudders (ie: barn door type) take lots of force.
Your best chance for using a tiller pilot with success will be a semi-full keel boat with a balanced rudder. Given that configuration a tiller pilot might actually be able to exceed it's rating, like an 8000 lb rated pilot can steer a 12000 lb boat. A boat that does not like to self steer, like a flat bottom fin keel boat, will need to have an oversized pilot. For example, use an 8000 lb rated pilot on a 5000 lb boat.
Remember also it's not a simple pass/fail thing. The more power the pilot has the more difficult conditions it can handle. I put a 20,000 lb rated pilot on my 15,000 lb boat and it can steer downwind with a quartering wave in 5' seas with 20 knots of wind. The original wheel style pilot would work in easy conditions but never in difficult seas and downwind.