Here's a couple of drawings ... One shows the motor mount template for 150-300 hp motors, and the other shows a twin setup and how the holes fit around the stringers (use the upper end of the lower slots if mounting twin outboards). The motor mount template fits on a 14-1/2 inch wide by 14 inch tall area - but it can be bigger too. My favorite setup is to have an aluminum plate made according to the outboard template, then mount a short (4" or 6") bracket or jack plate to the hull ... and mount the outboard to the bracket or jack plate. That makes a nice clean mount, room for the steering gear, and easier adjustability for tuning the height (jack plate).
FYI - The upper holes are 3/4 inch apart, vertically, measured center to center.
FYI - Also, if using a jack plate, you don't need a set of holes and a lower slot ... just 4 holes, the top 2 holes on top, and the top end of the slot on the bottom... do the adjusting with the jack plate. Even a low-cost manual jack plate (or bracket with adjustment built in) is fine.
Brian
