Of course it will be easiest if you can get the motor offm but you can do it with it on the boat. You will need a floor jack and some blocks.
Lower trailer tongue to the ground. Block two rear corners of the hull securely. Jack up trailer tongue until stern corners are resting on the blocks above the trailer. Block keel in front of the axles so boat is balanced. Lower trailer tongue so boat sits on 3 sets of blocks. Pull trailer forward until axle or crossmember is near the keel block. Now this part is tedious, you have to jack up the actual keel about 1/2" until you can remove and move keel blocks going back with the blocks towards the transom, 3-4 times or so, and pulling forward the trailer about a foot or two at a time. Safety first, careful. Do it on firm flat ground if at all possible. Another pair of hands is huge help, even though it can be done solo.
