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2hp performance


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I finally got out sailing this weekend after repainting and rerigging my cs17. One of the big changes was to add an outboard mount and evenrude 2hp outboard.

I had asked for advice on suitable power before I got the 2hp, and I had expected about 3-3 1/2 knots. Boy was I suprised :-)

I get about 4 knots at 3/4 throttle, and 5 knots at full, measured over a known mile on a lake. I think the shallow pitch 3 blade prop helps alot. In any case it just doesn't take much to move one of these boats around.

But, as expected once I was done playing with my new toy we started sailing and the outboard sat unused on its new mount for the rest of the day :-)

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;D Once I get her moving, I can move T e h a n i's 7000 (loaded) pounds at about 2 knots with a 2.2 hp. So I'm not surprised at your results. Takes a bit to get her going though!!

Jim Brown who designed the Searunner trimaran series and the Windrider tri, used to power his 31 foot tri fully loaded for cruising with he, his wife and two sons aboard, with a 4 hp evinrude.

By the way- I had to put the spaces in T e h a n i's name or the stupid spell checker or what ever it is changes it to Tehani

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Sailboats, as a rule are very easy to propel. The CS series are light, well shaped craft that are easily motivated to hull speed, with a minimum of fuss, as judged by their wakes. It goes to say, an outboard or trolling motor will have equally as little difficulty pushing her to hull speed, which should be about 6 MPH (don't know the exact LWL length for a CS17 without looking it up) for your boat. A steeper pitch prop may get you to 6 MPH. Matching a prop to an application is a bit of black magic, but basically it boils down to getting the engine to run at it's target WOT RPM under full load. If you're engine isn't running at it's target RPM (off by more then 100 RPM), then you could benefit from a prop change.

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well, yeah, that's all very true, but---

Our boat has a hull speed of about 5.6 knots - 17.9 foot waterline. We run an 8 hp 4 stroke engine with the standard prop at UNDER the start setting to get to the hull speed- at a high idle. If I changed props I'd still get hull speed, but I'd have to run the engine faster, which would burn more fuel. Currently we run 7 1/2 to 8 1/2 hours on a 3 gallon tank of fuel. We're probably using half of our available HP or even less.

I don't think I would want to mess with that ;D ;D

So it kinda sorta depends on the output power at the prop, at a specific rpm, which also kinda depends on the boat. WHOLE lotta difference twixt a Core Sound 17 and a full keeled displacement cruising sailboat.

Now I understand of course that wilh a deeper pitch I'd get better reverse, but that's a trade off I'm quite willing to make.

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