Re: Sailing ... transmission in reverse?
Note that Yanmar does allow you to shift into reverse while sailing if you have a folding or feathering prop. That's good since some props won't fold or feather without locking the shaft. Even so I usually put it into reverse for a few seconds, then back into neutral when the prop feathers.
When I had a non-feathering prop I did confirm on my own boat that freewheeling was faster than locking the prop shaft.
Putting on a feathering prop last winter was the best performance upgrade that I've made to the boat.
I'm no longer participating on SailNet.