Larson Composite Transom Leaks?

[mfawzy]

Wondering if anyone with a composite transom has experienced any issues? I have a '08 Cabrio 274 which I believe uses Coosa board in the transom. Does not leak at all while docked but takes on water when I'm out running it. Maybe 1 gallon per hour or less. Have not found any leaks in the waterlines or drain plugs. Could be that pressure on the transom while underway is allowing leakage. Sounds very solid using the knock test so I don't think there is delamination. Mechanic tested it on land while the engine was out and determined there is no Y pipe leakage and checked the gimbal seal to the best of his ability and found nothing. Bellows are brand new and I don't see leakage around the driveshaft to gimbal housing area. Thanks

 

[Scott Danforth]

Knock tests mean nothing

Does it leak with the motor running while tied to the dock, or just underway?

Use a flashlight, mirror and your phine on a selfie stick and look

 

[mfawzy]

Knock tests mean nothing

Does it leak with the motor running while tied to the dock, or just underway?

Use a flashlight, mirror and your phine on a selfie stick and look

Agree the knock test is far from conclusive. I'll run it this weekend in its slip for about 30-40min and see if it takes on any water. Just purchased an endoscope/inspection camera for my phone which will allow better checking of all the potential leak points. Will let you know. BTW, its not taking on any appreciable amount of rainwater, we've had lots of that and the engine bay does not accumulate more water while docked.

 

[Grub54891]

just had two at the shop, both didn't leak at rest. under way yup, the torque from the drive flexed the transom enough to make it leak. The transom's need to be rebuilt.

 

[JASinIL2006]

just had two at the shop, both didn't leak at rest. under way yup, the torque from the drive flexed the transom enough to make it leak. The transom's need to be rebuilt.

You had composite transoms that flexed enough to leak while under way? I’m not sure why, but I thought composite transoms were supposed to be pretty bulletproof.

 

[Grub54891]

You had composite transoms that flexed enough to leak while under way? I’m not sure why, but I thought composite transoms were supposed to be pretty bulletproof.

Sorry, they were not composite transoms. I misread the post.
But we had a composite dock at the cabin, it warped and cracked over a few years, but cosa board is a different material. It's a resin infused plastic of some kind? I'm still doubtfull about that kind of material as it can warp over time.

 

[JASinIL2006]

I would agree with previous replies that the knock test is pretty much worthless with a wood transom. Who knows if it's any better with a composite transom? I sure don't.

 

[mfawzy]

just had two at the shop, both didn't leak at rest. under way yup, the torque from the drive flexed the transom enough to make it leak. The transom's need to be rebuilt.

Thanks for sharing this, were both of them Larsons and if so, what year and model? Mine is a 07 Cabrio 274.

 

[Grub54891]

No, them were one bayliner, and a chapparal. Most transoms are built with the wood core.