All the above
I had a San Juan 21 with a 4 HP 2 cycle that got flooded out because of a following sea, the winds were 35-40 kts. The motor died, we were under bare poles, The only thing I could do was set the anchor with the bitter end tied to the mast step and waite out the storm at anchor. The next morning I brought the motor into the cockpit and started to pull the carburator to clean it, took out the spark plug and turned over the motor to get the water out of the cylinder. I was very lucky, after droping some oil in the cylinder and putting it back together it started up and has been fine since. On our Hunter 260 I had a 9.8 2 cyle short shaft that on a trip to Bimini from Miami the motor would come out of the water and over rev, making a racket, I did have the Power Thruster on the o/b and in that respect I don't think it made a difference. When setting the anchor, the weight of the person up forward would also over rev the prop I now have a 9.8 4 cycle extra long shaft and am very happy with it, the only thing I worry about is that the lower housing is lower than the center board in the up position, but I haven't had any problems. Knock on teak. John USNret