It's NOT necessary to have the
raw water thru hull closed for a pre-lube. The only reason to even consider that is that if you crank for more than 30 seconds you'll fill up the muffler with water. That is NOT a good thing to do. However, if you're only turning the engine over a time or two for short bursts, then just go open the thru hull, pull the kill switch up, turn the engine over, then push the kill switch down and start it up. Saves a trip up and down the companionway steps. While I've heard of this from a few sources, we've never done it. 1,900 engine hours, working just fine. Your boat, your choice.Paul, if you haven't yet please buy Nigel Calder's Boatowner's manual for Mechanical and Electrical Systems. It'll take a LOT of mystery out of your new boat.