Just curious, this has been on ongoing debate amongst my friends.  I don't think there's a right or wrong answer.  Seems like personal preference.

I would trim it up mainly to keep the algea from building up on the motor and inside the water pump. Also if you are on a lake thats infested with Zebra mussels or some other nuisance that has the potential to get inside and cause problems I would rather prevent the possibility of them getting in as much as possible.

Depends, If its on a boat lift I may or may not, in the water it would be a definite. Although on my little row boats I will just leave it in and it hasnt had any issues.

It stays in the last position it was in when I pulled up to the camp

I see no reason to trim it up other than to advertise what prop I'm running to anybody passing by.

Some of those that pass by may have the tools to remove said prop.

Another one on the prop, a guy that runs a marina told me he advises keeping the prop down in case another boat trying to dock doesn't accidentally run into it while docking.

If I beach the boat I trim down to keep the boat from moving side to side and getting into another boat. If I dock it's just where ever it happens to be.

I don't dock or beach at night, I anchor while fishing overnight. I used to trim down, but after having fishing line tangle arount the prop, I now trim up to keep fishing line out of it.     Happy fishing.

~B.A.S.S.~N.A.F.C.~BoatU.S.~N.R.A.~