Smoke under swim platform

[torcano]

After coming off of plane and placing the boat in neutral, I noticed exhaust smoke coming from under my swim platform. I checked my guages and the engine temps were OK as was the oil pressure. The only thing I noticed was that I still had my sterndrives trimmed out because I forgot to trim them in after coming off of plane. I never saw smoke coming out of boat before. I assume this was exhaust smoke and that by having the sterndrives trimmed out permitted the exhaust to escape above the water and into the air. Does this make sense? Where does the exhaust gas exit on a Mercruiser Alpha 1. The problem seemed to stop when I trimmed the drives back down.

 

[tashasdaddy]

Re: Smoke under swim platform

thru the center of the prop hub, you are correct in your assumption.

 

[Chris1956]

Re: Smoke under swim platform

Torcano, Alpha drives allow exhaust to exit from two places. One is at the base of the transom plate for exhaust relief at idle. The other is thru the prop exhaust. The swim platform and transom form a vacuum at speed and especially at idle speed. The fumes were sucked back from the Aplha drive and held under the platform. You never noticed it before, probably because the motor was burning some oil (foging or motor), but that area is normally full of carbon monoxide, which is colorless.

 

[QC]

Re: Smoke under swim platform

When I was in high school we smoked behind the tennis courts, your way sounds hard . . .