2009 306 Bimini Transom

[306Bimini]

Back in November 2023, I was doing routine maintenance on the Yamaha 350s when I noticed "swelling" on the upper transom from the bang plate down 5 inches. I was worried that water had made it's way into the marine XL plywood.
Well today my fears were confirmed that the plywood was saturated to the middle of the transom. To note the plywood was not rotted, just wet.
Attached are some pictures of the outer skin removed exposing the plywood.

 

[Sardinia306Bimini]

Hmmm, what will you do now? Replacing the whole wood in the transom?
One of the two 306 Bimini for sale here in Italy had a pert of the transom repaired as stated on one of the maintenance invoices.
As it was done in France I can't verify what and how it was done and that worries me a bit.
Chris

 

[TikiCharterFishing]

My 2007 305 Express had slightly higher moisture in the transom when I had it surveyed. Seems like it was about 1/3 higher than surrounding areas. I decided to just leave it alone.

In your case I think I would use heat to dry the wood and then test it with the hammer test for integrity. It might take weeks to dry it out but there’s no reason what went in can’t come back out. If the wood is solid, you could epoxy coat it and then build a high quality stainless steel transom cap that wraps down several inches. Reinstall the engines and know that the wood is better than it was before. I think you will save thousands of dollars.

 

[loubeer]

Out of curiosity, was the transom bang plate the original aluminum or had it been replaced? If original, was the aluminum corroded? I can't quite make out the bang plate from the original "before" picture. If not from the bang plate, do you have any suspicions as to where the water entry point was?

 

[Sardinia306Bimini]

and then build a high quality stainless steel transom cap that wraps down several inches.

Yes, that is what I would do if I close the deal. Probably so long on the outside the it covers the size of outboard mounting plate and wide as all the transom on the outside of the splashwell and all perfectly sealed with 4200 or 5200
Chris

 

[306Bimini]

Yes, that is what I would do if I close the deal. Probably so long on the outside the it covers the size of outboard mounting plate and wide as all the transom on the outside of the splashwell and all perfectly sealed with 4200 or 5200
Chris

Here are more pictures of the progress. Removed wet plywood. Replaced with coosa board. Laminate Fiberglass over the Transom and into the splash well. All sealed up with glass .

 

[306Bimini]

 

[306Bimini]

 

[306Bimini]

I'm very happy with the work. Took 9 days from start to finish. I am pissed at Grady with this poor design. Called Grady and of course out of warranty.
I had a few fiberglass companies look at it.
The transom was still strong before the repair.
I knew there was water intrusion because of the swelling of the glass especially in between the motors. You can see how wet the plywood was in the first pictures. I wanted to have it fixed before it got any worse. It's done and behind me.

 

[306Bimini]

Out of curiosity, was the transom bang plate the original aluminum or had it been replaced? If original, was the aluminum corroded? I can't quite make out the bang plate from the original "before" picture. If not from the bang plate, do you have any suspicions as to where the water entry point was?

It was the original bang plate piece of garbage. Yes the water seeps in between the bang plate in between the laminate on top and on the corners. Over time salt builds under the bang plate and pushes it out. Very poor half assed design. BTW....Grady is not the only manufacturer that has these issues.

 

[SouthFork]

Did you do the work yourself or did you have someone here in Martin County do it?

 

[306Bimini]

Did you do the work yourself or did you have someone here in Martin County do it?

Actually was repaired in Port St Lucie.... Tradition Area. Behind Bass Pro Shops
"Treasure Coast Customs"

 

[loubeer]

It was the original bang plate piece of garbage. Yes the water seeps in between the bang plate in between the laminate on top and on the corners. Over time salt builds under the bang plate and pushes it out. Very poor half assed design. BTW....Grady is not the only manufacturer that has these issues.

Thanks for the info - sorry for your situation, but I feel lucky that my dealer changed the aluminum to vinyl before I had the same problem. Your finished repair looks great - put it behind you and enjoy!

 

[Sardinia306Bimini]

Thanks for the great tread, it will come handy to many!
Chris

 

[306Bimini]

Thanks for the info - sorry for your situation, but I feel lucky that my dealer changed the aluminum to vinyl before I had the same problem. Your finished repair looks great - put it behind you and enjoy!

It doesn't matter if it's vinyl. the problem is with the hull to topside joint on the transom. Water can find its way in between the vinyl an the corner finishing caps.... thru screw holes etc.