Hi:

I bought a 19 foot seasprite boat last summer. It is a 1986. Last summer
I noticed that "on occasion" that boat would seem to "thump" after putting
it in gear. If I stayed at low RPM while leaving the boat ramp, it would
"thump" every few seconds. I couldn't really tell where the thump was
coming from. As soon as I gave it some speed, it worked fine.

I've had it out three times this year so far and today, the thumping was
especially bad. An almost continuous thump at low RPM's, and even some at
middle RPM's. When I have it full open, it seems to be working just fine.

Anybody ever had this, or heard of it, or have any idea what it might be? I
know you can't diagnose over the net, but maybe the symptoms sound familiar.

Thanks!