transom not flat around key hole

[harman79]

I went to mount my gimbal housing today and had trouble with the gasket sliding in. I checked my thickness and it varies from 2" to 1 7/8" I can fix this part easily by adding glass to the inside of transom right. How far out do I have to maintain the 2". Do I go as far as the transom plate sits. Also if I lay a straight edge across the outside of transom there is a 3/32 low spot. How can I correct the outside. This is a fiberglass boat with wood transom. Also what is the best way to check the repair for being parallel and at the 2" mark. thanks.

 

[Grandad]

Re: transom not flat around key hole

Hi harman, I doubt that the transom was built originally of varying thickness. I suspect that you may have some compression of the wood due to deterioration from moisture. Dare I say the word rot? I'd check what thickness changes you get if you apply a C clamp sequentially around the hole. If the area seems at all spongy, I wouldn't invest any more effort into installing the engine or outdrive until repairs are made. Perhaps a new transom. Your other threads indicate some cracking and problems with the cork gasket sliding, both of which could be the result of the fibreglass skin warping near the cut-out due to compression of the wood. I know that replacing the transom could be a big unexpected project, but if you assemble the engine to a rotten transom, I doubt you'll ever be satisfied with it. - Grandad :-(

 

[harman79]

Re: transom not flat around key hole

I forgot to mention I put a new transom in. When I measured the thickness it was 2" at the bottom and I must have never checked the top. It is at 1 7/8". I found the boat construction specs in the merc. manual and it says inner and outer parallel within a 1/8" which I am. the only think that seems not in spec is the outer surface. They say within a 1/16" and I am at 3/32" for 5 inches on both side in the middle of the gasket surface. How would I make that repair on the outside. Could I just glass the low spots where the gasket sits. I really don't want to do alot of grinding to the outside gelcoat.

 

[mxcobra]

Re: transom not flat around key hole

I would sand smooth and apply more gelcoat lie I did here...

 

[harman79]

Re: transom not flat around key hole

Are you saying I can use gel coat to build up the low spots on the outside. I know I need to add some fiberglass to the inside so I can maintain the 2 inches. what is the 2" to 2 1/4" spec determine. what would it affect if it was 1 3/4" or 2 1/2"?

 

[Bondo]

Re: transom not flat around key hole

Are you saying I can use gel coat to build up the low spots on the outside. I know I need to add some fiberglass to the inside so I can maintain the 2 inches. what is the 2" to 2 1/4" spec determine. what would it affect if it was 1 3/4" or 2 1/2"?

Ayuh,... The spline engagement length...