How do I know?

[twodzusfittings]

I recently sold my two stroke 9.9hp and have a new Nissan 9.9hp as a replacement. Looking at my Garelick engine mount, it looks like it should work, as the difference in weight is only five pounds. I am installing an aluminum backing plate on the outside as well as one on the inside to spread the weight over a 12x12 area. Is this going to do the trick? Anyone have any thoughts?

 

[inarathree]

If you put it on and it rips off the stern, then you know.

 

[kloudie1]

aluminum is probably going to be OK, but you'd be lots stronger if you epoxied/glassed a piece of 1/2" or 5/8" plywood to the inside. Make sure to seal the holes well and it will make a great base for the mount.

 

[Crazy Dave Condon]

Most folks think you have to epoxy and or glass the backing plate in place. NOt really needed. If you tighten the bolts and the holes are just big enough for the bolts along with the holes in the backing plate, once you tighten, generally it is not going anywhere. A 12 X 12 is plenty as you are really distributing the load. I use to be a Hunter dealer very much involved with the Hunter sailboats.

crazy dave

 

[twodzusfittings]

For those that would like to know, here is a picture of the finished product. The 12x12x3/16 plate on the outside was purchased for $25 with shipping from exactmetals.com, whom I found on ebay. My friend and I removed the bolts and removed the motor mount, cleaned off the old sealer. After drilling holes into the new plate, we reused the inside plate and bolts, attached it all with fresh SS washers and lock nuts. With lots of Life Seal under the outer plate applying plenty around the holes in the transom, we sandwhiched the transom. It all went together very well. The previous play of the mount on the transom has gone. I'll be waiting untill end of March to put the new engine on, so I'll update then if the whole task works or doesn't.

 

[twodzusfittings]

If you put it on and it rips off the stern, then you know.

Well the new motor is on. The difference in noise is incredible. Its so much quieter. Took it out for a long spin. All held together. So much for the smart alec's reply.:dance::naughty:

 

[Crazy Dave Condon]

Looking at the installed backing plate, I would suggest installing it inside. Why? First the outboard motor bracket in a sense is already a backing plate for the exterior. You need the backing plate on the inside to distribute the load from the inside of the boat vs. large washers; otherwise, I fear that stress will occur from the inside. Remember, it is called a backing plate as the plates were inside, not outside to help distribute the load. I use to be a former but now retired sailboat dealer having owned American Marine & Sail Supply.

crazy dave condon

 

[isaksp00]

My '23 has 2X4's as interior backing, and only the motor mount itself as outside backing. I have a heavy-ish Honda 8, and it seems perfectly fine. I do check for rot in the wood frequently, but it has been very dry so far, and I believe this is the original setup from around '91. I think (and I am no designer) the key is to distribute the load to a much broader area than just 4 bolts with washers, and that wood seems to do it.

 

[Crazy Dave Condon]

I had an email from two duzz fittings and there is a backing plate on the inside as well.
Although Iso is correct, two added a plate on the outside as well. The main thing is to have a backing plate on the inside to distribute the load as the motor bracket is also acting as an exterior backing plate. enuf said from me.