"Pull your spark plugs and cra
"Pull your spark plugs and crank it. The motor should turn that way. It's not going to be exceptionally loose (shouldn't, anyway) but it should turn.
How about a bit of history for this boat? How long have you owned it, what is the service history, what major repairs have been done, who does the regularly scheduled service and is that done on schedule?
You can pull the starter and test it with a set of jumper cables and a car battery. Wear safety glasses and if it just sparks without spinning, it was due or wasn't properly maintained. Starters are supposed to be lubed annually."