Transom Failure Incidents

[glacierbaze]

The acceleration test is too hard to eyeball, it might mean something if you held a straight edge across the inside during the test, to see if there was any deflection. Tilt the motors out, and each of you stand on a lower unit. That will test the construction, and your confidence.
How long have you owned the boat, and were the cracks there when you bought it. Regardless of how deep, or how superficial, the cracks are, the proper repair would be to grind them out, glass, and gel coat. Grady suggesting "flexible plastic pieces they had made specifically for that section", just makes me think less of their QC than I already do.
Maybe other Bimini 306 owners can paste similar pics, if it is that common. A lot of boats have spider cracks, but this is not that.
What is that black area above the Phillips head screw in the fourth pic?

 

[DennisG01]

Here is my experience. I have a 2004 Bimini 306 that has these cracks in the inside corners of the engine well- port and starboard. As you can see in the pics, the outside shows zero signs of cracking - not even spider cracks. I contacted Grady with these pics and they told me it was cosmetic and sent me replacement flexible plastic pieces they had made specifically for that section. I do have the advantage of being in South Florida so if water did get in, it would not expand during winter freezing. I also put my hand on the engines at idle and had my friend gun to full throttle- neither the transom nor the engines budged. I feel confident I do not have a transom problem......... I hope.

I agree that the acceleration test is nowhere near reliable enough. There's no way to feel minute movements while a boat is accelerating.

But... back to your crack That doesn't appear to be a crack. It looks like old sealant has separated. Dig it out, reseal, done. But first reach in there with a pick tool (or similar) and feel around to make sure things feel solid. Cover it with the new pieces, sure - but make you've sealed it well.

It looks like it might be time to replace your bang cap, too.

 

[Hookup1]

I am not sure why you say that. The transom is not showing any movement under stress and Grady White says there is no issue. Are you suggesting that a surveyor will see the edge cracks and assume there is an integrity issue? A side note- I was at a local Grady dealer and virtually every older Grady had the same cracks on the inside edge and no marks on the outside.

Look carefully at the rub rail top and bottom. Most of the transom failure I have seen were not like the one above in this thread (transom so bad the motors flex). What I think is more common is the transom and the stringers separate. The transom is held in place by the fiberglass on the rub rail and along the vertical sides. The power of the motors eventually stress the fiberglass to the point it blows out the transom assembly. I have seen at least two boats that sank this way and I'll bet there was some telltale cracking.

 

[Marty Cherry]

The acceleration test is too hard to eyeball, it might mean something if you held a straight edge across the inside during the test, to see if there was any deflection. Tilt the motors out, and each of you stand on a lower unit. That will test the construction, and your confidence.
How long have you owned the boat, and were the cracks there when you bought it. Regardless of how deep, or how superficial, the cracks are, the proper repair would be to grind them out, glass, and gel coat. Grady suggesting "flexible plastic pieces they had made specifically for that section", just makes me think less of their QC than I already do.
Maybe other Bimini 306 owners can paste similar pics, if it is that common. A lot of boats have spider cracks, but this is not that.
What is that black area above the Phillips head screw in the fourth pic?

I have owned the boat since 2009. I believe the black you see was dirt. The exposed aluminum angle piece at the top of the transom definitely has corroded a lot. Sounds like you know a lot more about this than I do which leads me to think I should find someone that doesn't have a vested interest in the potential repair to check it out. I will report back what is found when inspected. Thanks for your advice.

 

[glacierbaze]

Having an independent glass guy look at it is a good idea, but don’t give me any credit, I think I may have been completely wrong in assuming that it was a glass to glass joint in that corner.
After looking at some more Biminis online, particularly photo number seven in the ad link below, there appears to be a piece on the inside of the transom, which fits under the aluminum at the top, and goes about halfway down the inside of the transom, creating what looks to be a two piece bang plate. What that piece is made of, I have no idea, and it very well may have been caulked in that corner.

https://www.boattrader.com/boat/2006-grady-white-bimini-306-9066941/

 

[Hookup1]

I have owned the boat since 2009. I believe the black you see was dirt. The exposed aluminum angle piece at the top of the transom definitely has corroded a lot. Sounds like you know a lot more about this than I do which leads me to think I should find someone that doesn't have a vested interest in the potential repair to check it out. I will report back what is found when inspected. Thanks for your advice.

My boat is a 1997 so it's 25 years old. Materials choices and construction techniques were different then. I don't really know what was used in your boat.

I talked to the top glass shop in my area (Young's in Marmora). They weren't alarmed by the cracking I have. Usually it starts in the well corners (I have none there). They said yes I'll need a new $10,000 transom rebuild (probably $12,000 now) but they won't do them until it's time (too hard to take apart). I'll do the rebuild myself next Spring.

Assessing the condition of the transom/stringers is difficult without taking things apart. No one wants to hear that they have problem - they want the good news answer. The easy quick look doesn't go far enough. You really have to either drill lots of holes in the wood or peel back come of the glass that covers the transom and stringers.To do that you have to pull the deck out. At that point you are half way there!

 

[SkunkBoat]

Here is my experience. I have a 2004 Bimini 306 that has these cracks in the inside corners of the engine well- port and starboard. As you can see in the pics, the outside shows zero signs of cracking - not even spider cracks. I contacted Grady with these pics and they told me it was cosmetic and sent me replacement flexible plastic pieces they had made specifically for that section. I do have the advantage of being in South Florida so if water did get in, it would not expand during winter freezing. I also put my hand on the engines at idle and had my friend gun to full throttle- neither the transom nor the engines budged. I feel confident I do not have a transom problem......... I hope.

I think that style of transom has a separate piece of finished glass on the inner side of the motorwell. It has an L shape going over the top. The aluminum trim covers the top outside edge.
What you are seeing are not cracks but a split in the caulk.