Mike's plan sounds like it should work... I'd pull out the entire motorbox and any center floors that come out. Check it sitting still at the dock and leave it there for an extended period. Dont DO anything but sit & listen and look for water dripping or swelling from ANY of the through hull fittings (stabilizer fins, water intake, shaft packing gland, rudder port, transom exhaust exits, swim platform through bolts, etc). A small and a large mirror is a great idea...
If it remains dry - stay at the dock and start looking for a leak with the engine running. I'd start from your water intake hose where it connects to the through hull fitting (my hose was deteriorated AND it rubs the port side exhaust hose) and check all of your water supply hoses for rub spots & insure the connections are tight. Insure the engine petcocks / drain plugs are closed and keep an eye on the block for any water seeping. Check the rear / bottom of your impellor pump for dripping - it may be leaking if you impellor bearing is bad.
Also check your exhaust hoses - mine had a hole rubbed through on BOTH the port/stbd floors as they go into the bilge - you wont see it until you pull it away from the floor edges... If you have a heater (with the engine still running) crawl into the bow area with a REALLY BRIGHT flash light to see if your heater core, or one of the hoses going to / from it, is leaking - check the carpet for warm wetness. If not properly drained for winter storage water will freeze inside the core...
DONT ask me how I know all this...
Joel
