Thread: securing 8hp outboard to fiber glass fishing boat

You can use a piece of aluminum plate inside and out. threw bolt the corners then clamp on the motor. light weight and thiner profile.

I have used plywood cut just slightly smaller than the transom and then glued and screwed it to the inside of the fiberglass transom - which probably has a plywood core.

I used construction adhesive and screws that went into but not through the transom of the boat. The idea is to spread out the load both left and right and up and down. Finish the wood with a good outdoor sealer (Deck Sealer) paying particular attention to the edges where water can get in and de-laminate the plys.

When you say a little shaky I wonder what you mean? If there is flex in the transom you may need repairs before you mount the motor. If you mean it just looks like too much motor for the boat and you want something to give it extra support, you may consider adding an aluminum plate to the back of the transom before you mount to spread out the stress of the torque of the motor. Another add on is a knee brace between the floor and transom. Snoop around a boatyard and look at how some of the others have been done and you'll see some options done for different reasons. What Jimp said about bolting it down was spot on. I have had one jump off the transom while running and it was no fun, but I made sure it wouldn't happen again. I mounted a 1 1/2" wide strip of aluminum to the inside of the transom so the cups on the screw down studs that hold the motor on were just below the strip and couldn't come off again. Simple fix that worked fine for me. Using 5200 is a must whenever you drill the transom.