depends
whenever I tow an outboard boat I make sure that the weight of the motor is not completly on the transom, and is kept from bouncing. A small brace rigged up for the motor to sit in keeps a lot of the stress off, and preventing bounce by tieing it down works wonders. Most damage I've seen comes from people locking the motor in the up position with no other support or ties, puts a LOT more stress on the transom, or leaving it down and not locking it or tieing it which shock loads the transome every bump you hit. Ken