Bolting outboard on Catalina 27

[Brian Buzz]

I just bought a T9.9 hp high thrust Yamaha Outboard for my Catalina 27. I have the outboard model with the hole cut-out in the transom. My question is this: outboard came with a couple of long bolts to not only secure the outboard by the normal clamps but to drill through the transom and bolt it on. Do you recommend using the bolts? I hate to drill holes in the transom if I don't need to but what do you think?
Thanks
Brian

 

[Benny17441]

Let's put it this way, the engine designer thinks that you may need too or they would not have supplied the bolts. Drilling holes in the transom is not really a big deal as when you might not need them you can easily plug them up. The mechanics of an outboard require a sturdy mount as vertical and horizontal acceleration forces will be exerted on the mount in excess of the engine weight. Sailboats heel and you could have one clamp holding a pushing downward force while the other holds a pulling upward force. I have seen in rough waters the stern of a sailboat drive an outboard engine down in the water submerging the cowling cover just to quickly pop out to lift the engine propeller out of the water. We were running an outboard bracket an I though for sure the engine was going to get ripped off but it held. It was a 2 stroke Nissan 9.8HP weighing under 60 lbs; If it had been a 4stroke engine weighing 120 lbs it would have been gone. Don't know how strong the mounting support for the clamps might be but if it were me I would also install the screws. To drill cover the location for the holes with masking tape to prevent the gelcoat cracking. Use an epoxy to seal the interior of the holes and caulk the bolts. I would use a backing plate to sandwich the transom wall and distribute forces along a larger area. If you don't use them you will always be wondering...….. Peace of mind is priceless.

 

[Tom J]

I had the 9.9 hp Yamaha on my O'Day 23, mounted on the transom cutout. This was quite a few years ago, and the bolts weren't an option. The motor was very secure, more than it would have been if it were on a bracket. I removed the engine for storage at the end of every season, so I probably would have skipped the bolts if they were an option.
Like Benny said, though, drilling the holes is no big deal, and might be worth it for ultimate security.

 

[Brian Buzz]

I bolted the outboard on today. The motor falling off the back is now one thing less I got to worry about. Thanks for your
detailed responses.
Brian

 

[ZackB]

Irwin 28.5". No room to work to install backing plate in transom. Was thinking of putting backing plate on outside of transom in cockpit then fill 3 1/2" cavity in the transom with Evercoat 100654 Sealant Foam. I am thinking the foam would spread the push of the outboard over a larger area of the transom. The backing plate in the cockpit would just be acting to allow access to nuts and washers. Any ideas on why or why not this would work?

 

[BeachGuy]

Looks as if I'm a day late to the party. So for anyone in the future who researches this forum needs more info here are a couple of photos from my install of a Suzuki 9.9 long shaft 4 stroke on my 1980 Catalina 30. No more stinky 11 hp diesel and all it's 40 year old problems in the boat. Sail Gulf of Mexico and local bays. Will push the boat at hull speed at 2/3 power.