Transom height question

I've decided to replace the transom on my 14' jon while doing some other work on the boat. I run a 1956 Johnson 15 hp FD-10 on it. The shaft length of the motor is 18" (top of transom to cavitation plate.) The transom on the boat is 15", and since I will always run either the FD-10 or my 1958 10 horse Evinrude (18" shaft) on it, I was planning to raise the transom height to 18". The boat has always run great, but has never seemed to plane out well.

I thought I knew that putting the cavitation plate about even with the keel was correct, but then today I read that some of the older outboards need to be set deeper to pick up water, keeping the water pump below water level because they are not self priming. Made sense to me... then I thought... hey... the keel is several inches below the waterline when the motor is first started, and only gets near the top if the boat is planing extremely well. Once the water is pumping, as long as the pickup is under the surface, it will keep pumping.

So here I am looking for answers <G>. Any thoughts on the subject would be appreciated.

Tom

Re: Transom height question

your 15 inch transom is correct for those motors. you might slip a piece of 1x2 under it, but that is all. planing, distribute your weight properly, and moving the tilt pin closer to the transom will push the bow down to plane, too far and it will make it plow.

Re: Transom height question

To be honest, I hadn't thought about plowing. I just went out, stepped back from the boat, and noticed that the motor shaft is tilted in quite a bit. I can go one notch in or two notches out. I think I'll let it out one notch and see if that solves the problem. The boat always seemed to level out, but the wake it made was huge at any speed. Plowing makes sense.

Thanks!
Tom