Quick question

[el_caboing]

So I was changing my trailer lights this past weekend to some new submersible led kind. I raised the motor up and for some reason saw something that made no sense to me. It seems where the motor bolts to the transom, the bolts have gone right through. I have a 16foot aluminum grumman. So my plan is to get some 2"x2" stainless steel plates with a hole in the middle and sandwich them on either side of the transom with some marine adhesive and then bolt her down. So my question is will the stainless and aluminum cause issues if they are together and eat away the aluminum or is there a better way to attach the motor? Thx in advance.

Steve

[jona38]

If you can post if few pics.

[Kerrazy]

That my friend is what happens when 2 different types of metal meet. Steel in either stainless or iron form when against aluminium and offered water will cause the aluminium to oxidize. To prevent this ensure there is a non conductive barrier between the two. Something as simple as some PVC or rubber.
I would suggest a piece of 1/4" aluminum rather than stainless as it is similar metal and then I would put some sort of a rubber shoe over your motor transom screws.

[Daboss]

http://en.wikipedia.org/wiki/Galvanic_corrosion

[el_caboing]

Ok, so as long as I put some sort of barrier between the stainless steel plate and the boat I should be ok. One more question, it looks like the motor does not fall flush with the transom as there is a lip at the top where the clamps are on the boat. Would i cause a lot of damage if I were to cut a piece of pressure treated deck board and use that as a filler for the motor to connect to the transom on the outside of the boat? I'll try and get some pictures up. Thx again.

[ShawnD]

I'll try and get some pictures up. Thx again.

Please do.

[Kerrazy]

Ok, so as long as I put some sort of barrier between the stainless steel plate and the boat I should be ok. One more question, it looks like the motor does not fall flush with the transom as there is a lip at the top where the clamps are on the boat. Would i cause a lot of damage if I were to cut a piece of pressure treated deck board and use that as a filler for the motor to connect to the transom on the outside of the boat? I'll try and get some pictures up. Thx again.

Pressure treat and aluminium are not a good mix. I would use some good old 3/4 plywood, and seal it with either epoxy or a good primer and an acrylic latex paint. I carve big signs, and commonly use an acrylic latex to ensure they stay sound for many years.

The chemicals in the pressure treat, when wet will leach out and cause a corrosive reaction with the aluminium.
Again, just keep it simple and reinforce the area with a chunk of aluminium plate, than you will never need to touch it again.
Kerrazy

[el_caboing]

Ok first time posting pics so not sure if it will work. So this is what I am talking about. Any help is appreciated.

[Kerrazy]

Ok. So from your photos, it looks like you have a real problem. A 2x2 chunk is not going to cut it.
But all is not lost. You could put in a piece of aluminium a large piece the size of you transom 3/16" thick and it would be good for years. You could even make a template and have it custom fabbed then pop rivet it in place. It looks like you have lost any structural integrity in your transom. Pm me and I will shoot you my ph# and explain a little more.
Kerrazy

[el_caboing]

So if I put a 2x2 chunk on the outside and a 2x2 chunk on the inside and bolt those together with marine adhesive it will not work? Apart from the hole there doesn't seem to be any real issues with the transom.

[Kerrazy]

A 2"x2" piece does not transfer the load enough. As it is corroded, you need to reinforce that over a greater span. I suspect the 2x2 area will just pull through in no time as the area is already compromised.

[CNs]

Ok. So from your photos, it looks like you have a real problem. A 2x2 chunk is not going to cut it.
But all is not lost. You could put in a piece of aluminium a large piece the size of you transom 3/16" thick and it would be good for years. You could even make a template and have it custom fabbed then pop rivet it in place. It looks like you have lost any structural integrity in your transom. Pm me and I will shoot you my ph# and explain a little more.
Kerrazy

Great advice Kerrazy.

[StarTzar]

So if I put a 2x2 chunk on the outside and a 2x2 chunk on the inside and bolt those together with marine adhesive it will not work? Apart from the hole there doesn't seem to be any real issues with the transom.

Do yourself a favor and call Dale.

[Mike586]

Whatever you do, do not use pressure treated wood on an aluminum boat. Because of all the copper in pressure treated wood, when its in direct contact with aluminum, particularly in moist conditions, it will cause the aluminum to corrode.

http://en.wikipedia.org/wiki/Galvanic_corrosion

The cheapest route would probably be plywood sealed with epoxy, or marine grade plywood. The best wood would be white oak or mahogany and they would require no special treatment as they naturally resist rot pieces usually lasting decades before needing replacment.