[willy]

My Merc 150 tested low and un even on a compression check by the certified tech, brought it home, my 75 year old fisherman/boat experienced buddy brought over some stuff to decard the engine like MJ says and we did a job on the engine.
So much in there I white fogged my whole neighborhood for half an hour. When all was said and done compression was back up to close to normal, a little lower than a stock fresh engine would be. Ran like a monster after that because we also cleaned out the carbs while we were at it.
Also there are thousands of engines out there that run every year with low compression as they age. The big problem is if you have 1or 2 cylinders that are real low. So low compression should not be keeping you from the water.
The lower unit has water in it. Could be as others have said and someone did not replace the washers on the drain and fill screws, or they replaced just one(like happened to mine) or they over tightened one or both and cracked or split one of them.
So check it out, if they are ok and you are actually leaking from a prop seal or you may be leaking from an improperly torqued reinstall of the lower unit.
If it is the seals that have to be replaced then you can do two things, pick up a little jar of SealLube from New Tech or whatever prodet you have in your area for the job and add it to your lower unit oil, if it is a slow leak seal type of theing it will close them up good and you can finish the season on it.
Or you can lay out the cash for a new motor if you got it to run with, that is always a nice option to have. But I would not miss the tournament due to the issues stated unless the motor is dying or stuttering on you then I would not take the chance but if it runs good just a little low on the upper end power wise go for it ;)