guys with transom outboard brackets.
 

I am trying to figure out how thick to make my transom. Any of you guys know how thick you all transoms are?

My 86 came with a sea drive, looks like it would also be the same transom as an io, but a guesstimate on mine would be 2 1/2-3 inches.
Next time I go down to the boat I'll measure it up, and post back.

Thanks, I am thinking I am going to use 3 peices of 3/4 and then glass over. That should put me at the numbers you are saying.

The strength isn't in teh thickness so much as it is in the layup. Also put in a set of knee braces on each side of where the bracket will atatch. Make it so that the load will go through the hull instead of the transom so much.

I will definitely put knees between the two. Also I will use some good size plates of aluminum for washers where the bolts will go through the hull.

I put a progressive patch on my transon in between layers of 1708. It helps to distribute load from the brackets bolt pattern. I wetted out a 10x14 patch on my core then put on my first layer of 1708 that lap back to the hull 4 inches, I then put a 14x16 patch and then put my second layer of 1708 that progressively lapped back into the hull 8 inches. I put another patch that was 18x18 over that layer and then applied my third and final layer of 1708 that progressively lapped the hull about 10 inches. my core material consisted of 2 layers of 3/4 plywood. the bolt patch is just another way of adding strength and distributing load with out adding a bunch of weight. notice in the picture the dark green in the middle of the transom were the patch was layed up

Basically you added another piece of ply where the bolts would bolt up?

ply as in core material? no the bolt pattern patches were cut out of 1708 cloth and were wetted out and incorporated between my 3 whole layers of cloth. I was trying to give you someother ideas for strength without adding a bunch of weight to the transom. maybe go with 2 layers of 3/4 (which is factory core thickness) and then add a 1/2 inch piece of core ply to make a total core thickness of 2 inches. But I truelly dont see why you cant just put 2 pieces of 3/4 ply and then incoporate transom knees, guys run em like that everyday with no issues. as was said earlier thicker is not more strength, the strength is in the layup.

mine was 2x 3/4 plty, then bolted on the bracket with a custom bar out of 1/2 steel to distrbute the weight.

http://www.wellcraftv20.com/gallery/...icture_016.jpg

Makes sense now. I think 2 pieces of ply, with knees tied into the stringers and then make a plate like mj has out of alum. Should take care of things