PDA

View Full Version : Caledonia "Launch"



Mezzaluna
02-24-2007, 02:40 PM
I'm planning on converting a Caledonia Yawl, dbl. ended open boat, which I build several years ago to more or less full time motoring status. (I already hear the cursing, the wailing and knashing of teeth). But the so called facts are inescapable, where I live the wind is never right- it's too much, too little and always the wrong direction. It's frequently wrong in both directions, wrong when you're going out and equally wrong when you turn 180 degrees to head in. A full time motor would allow me to actually use the boat more often. What I'm thinking of is a sort of inboard launch sort of thing except with a small, 5-8hp, 4-stroke outboard, tilt-able, in a covered well. I know the sensible thing would be to get a more suitable boat, but I love the boat and I'm not going to be building anything else in the near future.
Anybody done anything like this?

mcdenny
02-24-2007, 03:25 PM
You must like sailing to have built a sail boat. You could keep the quiet and fresh air by using electric power. That double ended hull would drive very easily. 250 lbs of batteries shouldn't hurt performance too much. 4 - 5 mph for 3 or 4 hours ought to be possible.

Briggs & Stratton http://www.briggsandstratton.com/display/router.asp?DocID=81400 has a 3 hp electric outboard priced about the same as the 4stroke gas OB (about $1800) that ought to get it up to hull speed with (4) good size 12v batteries. RE EPOWER http://www.re-e-power.com/ also sells an under hull electric drive pod which is more expensive but looks pretty slick if you can stand the permanent under water protrusion. A 'normal' inboard installation with a small skeg would work well too but with a good bit of construction complexity. Under sail with the inboard or pod a tiny bit of electricity can spin the prop at boat speed and eliminate the prop drag.

The motor used in the Briggs OB is available in the aftermarket as are other suitable motors. They are only around 8" dia, and weigh 20 -30 lbs so can be mounted in a small space. The batteries of course are a lot bigger than a gas tank but can be distributed throughout the boat as long as the proper CG is maintained.

JimD
02-24-2007, 03:51 PM
I'm in a somewhat similar situation and am in the process of building a well in a Glen-L Minuet and redesigning the sailing rig to simplify the amount of deckwork to a bare minimum. You might want to keep at least one sail on a short mast to assist the motor for those few times when the wind is ok as in this Atkin Periwinkle. A small sail can steady the motion of a powerboat for a more comfortable ride, too:

http://www.boat-links.com/Atkinco/Cruisers/images/Periwinkl-1.gif

Pytheas
02-25-2007, 12:26 PM
I usually sail or row a Calidonia Yawl but occasionally when I have guests I put a 2HP, 4-stroke Honda in the motor well and parade around Chautauqua Lake. With four aboard and little else the boat reaches hull speed or close to it. By my calculations the boat needs 2.2 to 2.6 horsepower, according to who's formula I use, to reach hull speed. Allowing for adverse winds, waves, heavy loading, etc. and a bit extra capacity for the engine's sake, a 4HP should get you around in most conditions as fast as the boat will allow. I put more priority on low engine weight, low noise and fuel economy and went with the Honda 2HP. My only complaint is that even this is noisier than I would like. For that reason an electric motor might be just the thing. A formula I found on the Web showed a 17lb-thrust setup would be needed. Maybe someone else has some experience there.

Usually I keep the engine fixed and use the tiller to steer. Reversing with this engine requires unlocking the pivot and spinning the unit around - not a problem to me. With the propeller pointed to starboard the hull and keel are in the way, thrust and control are poor.

Another consideration is the drag of the open motor well. Mine is not a tip-up type. From the churning water in the well under power it is obvious there is considerable drag. In rough water some may come over the top.

The Calidonia seems just right as a launch to me. Even in motor mode people cross the lake to take a closer look. I think you'll enjoy your "launch." Let us know how it turns out.

JimD
02-25-2007, 01:33 PM
Just a guess but a 17 pound thrust electric sounds like very little power. I have a 65# thrust and could use more. The obvious problem with electric is making sure you don't run out of battery charge.

Dave Lesser
02-25-2007, 02:08 PM
Pytheas, check your PM's