The GM Vortec marine engines run 9.4 to 1 compression, so that is what I aimed for, making sure I had good .040 quench. Would I be better off going up to a .050 quench and lowering the compression to 9.2? At the fuel docks it's usually 93 and sometimes 89 Octane. I plan on keeping some good Octane boost on board in case it's an issue at unknown docks. I'm running Volvo drives and they use a cone clutch so that should also help with shifting around the docks.