How deep do you put your trolling motor prop?

I have been told from 6 inches to 2 feet so something is not right.

Ahd to measure from 1) the water line and 2) the top of the deck.

Thanks guys.  I sincerely appreciate your input and guidance.

I believe to maximize efficiency it should extend below the keel of the boat, but I seldom lower it that far because of weeds, timber, etc.  As long as it is not throwing a wake on top of the water, it is probably low enough.  Of course in heavy wind/waves it needs to be even lower to stay in the water and prevent cavitation.

I just set mine so it sits properly on the mount when its not in the water. If it gets hung up, then I just lift it up with the rope and use it on low speed until i'm clear of the obstruction. Most of the water here is relatively deep though, so my 50" shaft trolling motor is probably all but 2" or so below the mount.

It all depends on where I'm fishing.If I'm in water that's deep enough not to hit stumps and other wood cover,I have the motor down fairly deep.When I'm fishing shallow,stump and snag infested waters, I raise it up to about a foot under the surface of the water.