The Ensenada 20 came with a factory installed, spring-loaded, raisable mount for an outboard motor. Ours is securely affixed with four carriage bolts through the transom and a 3/4" plywood backing plate inside. The whole shooting match seems to be well bedded in place with epoxy or something similar: even after removing the nuts we were never able to budge the mounting bolts, backing plate, or bracket even a tiny bit. We hope we never need to take it off!
The motor mount is easily secure enough to hold our 50 pounds of 8 HP Chrysler. However, under the thrust developed when that engine is at full throttle, something disconcerting happens. The engine is the 25" shaft model, so the thrust of the propeller is down at the end of a 25" lever. It doesn't just push the boat, but tries to twist the whole engine and mount up and forward at the bottom, or counterclockwise as seen from starboard. I shouldn't say "tries" to twist; at full throttle we can watch the transom fold in near the bottom of the mount and its backing plate!
A number of hairline cracks in the gelcoat near the top and bottom of the
mount bracket confirm that it's been doing that all along, so we extended the
inside backing plate all the way down to the hull bottom and tabbed it in place
there.
We haven't had a chance yet to test it at full power, but we expect this will
greatly reduce the inward flex at the bottom of the engine mount.
The original plan was to just replace the original backing plate but, given the difficulty of removing it, we just added to it, as you see. The darker plywood is the original backing plate.