I might be onto something
 

Ok,
I went into the boat this afternoon to get into the cabin and glanced back into engine compartment where I had recently removed my headers from my starboard motor. Something looked funny inside the rubber exhaust hose (tailpipe to thru- transom tip). Upon closer inspection the rubber had de-laminated on the inside forming kind of a dam about an inch high. Is it possible that this is what has been causing the water to get into my exhausts (at shut-off water could run forward instead of draining aft.) and then running back into cylinder #7 and then into my oil? What do you all think? - Jeff

Possible, but I thought you were having your biggest problem with water getting in your oil after after running hard for a while.

actually no griff,
the water migrated in from mostly light running idle to 2500 rpm.
thanks. - jeff

Do you have silent choice?
I had a water problem once and it turned out to be the rubber flappers in the Y pipe had burnt off and blocked the exhaust and water in silent mode.
If you don't have silent choice - the rubber dam could cause the water to build up in the exhaust and then causing reversion.

Tinkerer,
I don't have silent choice but I'm still wondering if my blockage is the cause of my current trouble. - Jeff

then I would say the damn created by the bad hose could cause it, but i would think you would have seen other effects as well if the water had leaked back into a cylinder. I had an issue with a cracked manifold that leaked water into one cylinder and obvious the there was water intrusion on the valve. It was rusty and pitted, but I still never got water in my oil.

griff, thanks for responding. when i go to start the motor sometimes it turns and stops abruptly, i imagine from water in the cylinder.( and the spark plug from #7 cylinder did indeed dribble water out when removed). i was thinking that during compression stroke the water in the combustion chamber leaked past the rings down to the pan. does this make sense? - jeff

Absolutely YES, my buddy Mike had this exact problem on his 311. The hose split inside and the inner lining would drop down like a flapper, this caused water to back up into the engine and filled the oil. We pulled the whole engine down before we realized what happened. If you were getting a stop while starting it is likely due to a cylinder hydro-locking-you may want to check for a bent rod.

With all you've described, I say the hose was definately the problem. I would pull the exhaust on that side and inspect the # 7 valve.

insptech and griff,
thanks so much you guys; some days i think we wouldn't really spend many days on the water without each others' help. i appreciate you sticking with me while i'm sorting this out. - jeff