Re: Hydro lock?
They said you MIGHT have a hydro lock, pull the plugs and turn the engine over (By hand preferably) and see if water comes out of the cylinders.
I also asked about why you was messing with your timing in the other post.
If you boat in salt water, your exhaust manifolds, risers, extension, or the gasket surfaces between them may be compromised. They are at the end of their life in salt water.
When you shut off the engine, the water will leak out of the exhaust and leak into a cylinder with open valves. Bingo, hydrolock, and starter damage if you keep trying.