Re: shaft length question - again!
Those smaller engines seem to run deeper in the water so I'd say you have a short shaft. One way to tell is to look at it from the side.
Short shafts look balanced; like the lower unit mid section doesn't seem to be disproportionally long. Long shafts just look funny; lower unit seems very long for the rest of the engine.
I think long shafts (other than for sailboats) are probably special order and not that popular, even though they are available. Most 12-14' fishing boats sport a 15" transom and the anti vent plate is well under the water when running.....have looked many times.
Sorry, that's the best that I can do.
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Thought about it some more before I shipped this off and you have a short shaft. No way you can run a 17 1/2" lower unit on a 20" transom at that hp rating and properly propel your boat.
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Still thinking. You said that you are stuck with it if already short.....you can put some shims between the transom top and underside of the clamp bracket. I have done that on several occasions. I used 1x2 redwood strips....but expect some ventilating if you get it too high.
Most boats of that size have a very definite keel protruding right in front of the engine and that disturbance will make her spin up on turns.
If you are worried about the engine coming off, like if your clamps are right near the top, bolt that sucker on to the transom.....unless you remove the engine frequently.
Mark
