Transom Separated on 1991 Thundercraft

[bytecrafter]

I have a 1991 17' Thundercraft. I noticed yesterday one of the engine bolts was pulling through the transom. I was worried the transom was rotten and starting to collapse on the inside. But upon further inspection it appears as if the fiberglass and the plywood have separated. The transom is bulging to the outside along the middle section on the top. I removed a bolt and a drain plug and the plywood seems solid. I did a tap test and it seems solid except where it has pulled away. If I had to guess, by the look of the rivets along the aluminum trim on the top of the transom, the transom has been replaced at least once. I am going to take it apart when I am on vacation and take a closer look, but assuming the plywood is good and it is just separated what is the best way to repair it.

I push with a 90hp Mercury OB.

Thanks,
Bill

 

[bytecrafter]

Re: Transom Separated on 1991 Thundercraft

Hi,

What I am really asking is what is the best way to glue the plywood and fiberglass back together? What epoxy should I use? Should I consider adding reinforcement or is just gluing it back together enough?

Thanks,
Bill

 

[bytecrafter]

Re: Transom Separated on 1991 Thundercraft

Also the top of the middle of the transom is open except for a strip of aluminum strip riveted along the top. Was it factory built this way? Would it not be better to be fiber-glassed over the top to both sides?

Thanks,
Bill

 

[boatnut74]

Re: Transom Separated on 1991 Thundercraft

Some pics would be helpful.....

From the sound of it the transom is likely rotten. The tap test isn't always accurate as any fiberglass covering will make it sound solid. Drill a couple core samples and see what you find. Most outboard boats have that aluminum strip on top of the transom as a cover / shield.

 

[bytecrafter]

Re: Transom Separated on 1991 Thundercraft - Pictures

Re: Transom Separated on 1991 Thundercraft - Pictures

Here are some pictures. I picked away a piece of fiberglass at the cracked bolt hole and the wood underneath is solid as a church - dry and blond in color. Same as the wood in the drain hole about 4 inches away. It seems just the plywood transom has separated from the inner fiberglass.

I have not had time to take it apart yet - a close friend passed from flesh eating disease and the funeral was yesterday.



Thanks,
Bill

 

[bytecrafter]

Re: Transom Separated on 1991 Thundercraft - Pictures

Re: Transom Separated on 1991 Thundercraft - Pictures

I built a motor stand yesterday so I am about to take the motor off and do the repair. My assessment until I get it apart is still that it is just separated between the plywood and inner fiberglass hull and needs to be re-glued. Based on what I have read the best adhesive is West System Micro Fiber Blend 403 - would you agree.

Thanks,
Bill