Down when it's in the water, up any time it is not.
If you think of the physics involved, towing with your motor down puts a lot more leverage on your transom (not to mention the risk of smacking the skeg pulling into the gas station). Towing with the motor up balances the weight between the powerhead and the lower unit on top of the transom - where it is strongest.
You should have a lever on the motor, or a block to put in the strut, to take the tension off of the hydraulic trim.
If you think of the physics involved, towing with your motor down puts a lot more leverage on your transom (not to mention the risk of smacking the skeg pulling into the gas station). Towing with the motor up balances the weight between the powerhead and the lower unit on top of the transom - where it is strongest.
You should have a lever on the motor, or a block to put in the strut, to take the tension off of the hydraulic trim.