Re: Water in Cylinders
If you can figure out (head off) which piston is frozen then freeze the piston with CO2 or 134a refrigerant. This should shrink the piston enough to allow it to come out.
Plan on buying pistons any way and if you can save them it's good.
A normal piston will have some slight wiggle at room temp. A frozen (corroded) one won't. Too much force (hammering) will ruin the lands (grooves) in the piston. If not too bad they can be fixed at an automotive machine shop.
Chances are good that the bores are ruined also. More machine shop stuff.
If you can get them out with no other damage go buy a lottery ticket. Your luck will have changed for the better!
Seafarer 29 KCB