Postby jimh » Wed Jul 15, 2026 10:07 am
From the two illustrations provided (above) there is no indication if the transom has been drilled for engine mounting. If there are holes, you need to measure their positions to see if they are correctly located. If no holes, you need to drill them.
Many professional outboard engine installers use a metal template to assist in locating and drilling the holes. If you don’t have a template, be very certain to carefully check the positions before drilling the holes.
Also be sure to use sealant on the fasteners as they pass through the transom to prevent water from reaching the embedded wood in the transom.
The usual orientation of the engine mounting bolts is to have the head of the bolts on the inboard side of the transom, and the securing nut on the outboard end of the bolt.
The bolt length should not be excessive. Use shoulder bolts so most of the portion of the bolt in the transom is smooth and not threaded.
On the inboard side, use large, thick, square aluminum plates to spread the load onto the transom so the hull laminate won't be crushed under compression by the mounting bolts. On the outboard end, use normal washers under the nuts to spread the load onto the engine bracket.
If necessary, cut off excess threaded portion of the bolts to produce a cleaner installation. An elastic stop nut can be used to prevent the nut from loosening. As a finishing touch use a nylon or plastic cap to cover the end of the bolt so remove any sharp edges.