Randy: The M15 has a limited hull speed. TheHonda 2hp is able to provide enough power without any problem, even against a 2.5 knot current on SF Bay. The added weight of a 5hp on the transom is too much for the M15 to carry, in my opinion. You can purchase a new 2hp Honda 4 stroke for $ 699.00 with a neutral. I recommend you try a 5hp and a 2hp on the M15 before you buy one. It's an important decision. Rich Cottrell Randy Dawson <rdawson@surewest.net> wrote: Sorry if this is off topic and I know this subject gets totally hashed but I am in the market for a 4 stroke outboard for my M15 and need to know the transom height or how to measure it. My boat is an 89 model with the fixed motor mount. I know that the Honda 2hp is all I need and is the bomb BUT, Stockdale Marine has a Briggs & Stratton 5hp for less $$ AND it has neutral, forward and reverse AND an external tank so I can cruise the river all day if no wind. Thanks to anyone who responds. All comments welcome. Ran Dawson Little Wing Folsom Lake California _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats