Transom Rotted

[Benny67]

Keep in mind, your boat had a 15 year design life and its 32 years old

Dolfan,

LOL...yes, the engineers that designed this boat in particular were planning it's demise just in time for it to cause you heartache. However, they miscalculated the time for it to leak by 17 years.

PLEASE....If this were the case, everything you buy would have to have a expiration date on it.

Things wear out due to negligence and mistreatment. NOT because it's designed to fail in a certain amount of time. It's not chicken you buy at the market, it's durable goods.

 

[tank1949]

Here’s me, about 205 lbs, on the outdrive!

From your photo, of course no caulk is present between your metal OD and glass. With a synthetic transom, it will not rot, but water will eventually get past failed or weakened seal or transom bolts. In addition, ANYTIME your make a bolt or screw hole in any boat, ALWAYS fill with caulk, preferably 5200 before adding bolts or screws. There are typically 8 7/16 bolts holding a MC transom assembly onto a transom. You may not want to add 5200 to those bolt holes because it might take an act of God to remove the assembly, if repairs are needed later on. But, at least coat inside of holes with paint or epoxy to TRY and seal the wood or keep bolts from rusting. Good luck! Boat builders sell "pretty."

 

[dolfan1710]

Thanks for the advice. I’m just skeptical because I’ve never seen my boat take on water before and was just out with the hood off working with the battery wires and wires on the starter and didn’t see an alarming amount of water. Then the mechanic takes it and I’m being told 4 or 5 gallons are pouring out after an hour or 2 on the water. That’s a big difference. If I’d seen it and was told my transom was rotted I wouldn’t be questioning it. I’ve been super busy and haven’t been able to go out and see it for myself which is what I should do. I should see water entering with the hood off correct?

 

[Rick Stephens]

Size of a leak has nothing to do with a transom rotting or not. I know for a fact you can have a leak that never puts a drop of water in the bilge and it is enough to rot a transom. My leak was from unsealed and a little bit loose sonar mounting bracket screws. Those and trim tab screws will let water into the transom wood directly with no connection to the bilge at all. Only way to know if a transom is rotted is drill a few test holes low down and see if the wood is mush or not. You can fill said holes with 5200.

 

[JASinIL2006]

I don't think jumping on the outdrive will tell you much, except if it does move, you have problems. Mine was very solid, yet I had pretty substantial rot around a good bit of the keyhole.

My rot started from loose (and poorly sealed) swim ladder bolts, just like yours. The water got in through those holes and wicked along the wood inside the transom. By the time I discovered it, much of the wood on that side of the transom was mush or was on it's way. And yet, the outdrive 'seemed' solid...

 

[dolfan1710]

I don't think jumping on the outdrive will tell you much, except if it does move, you have problems. Mine was very solid, yet I had pretty substantial rot around a good bit of the keyhole.

My rot started from loose (and poorly sealed) swim ladder bolts, just like yours. The water got in through those holes and wicked along the wood inside the transom. By the time I discovered it, much of the wood on that side of the transom was mush or was on it's way. And yet, the outdrive 'seemed' solid...

Is there anything I can secure that swim platform from the outside? FYI, I know this boat is very old and I plan to move on from it I'm just trying to get one last season out of it. Only one bolt seems really bad, is there a product I can use to seal it so it won't leak?

 

[Rick Stephens]

Is there anything I can secure that swim platform from the outside? FYI, I know this boat is very old and I plan to move on from it I'm just trying to get one last season out of it. Only one bolt seems really bad, is there a product I can use to seal it so it won't leak?

If it is solid enough to run safely, who cares if you seal it at all if you are running for just a season?

 

[JASinIL2006]

Something like 3M 4000 would work, but you really need to get at the back side of the bolt to tighten it (assuming the wood isn't mush and the bolt can be tightened...). If you don't tighten the bolt, any sealant you put in there won't last long because the ladder flex and pull away the sealant.

 

[dolfan1710]

Got the bolt out from the back. the wood around the hole doesn't seem that bad. I think there is enough room above the gas tank for me to push a new bolt through with an oversized washer. I think it will hold the wood felt OK, just the screw hole was completely rotted through. Seems like its going to be tough to get it to come out of the back of the boat though. I'm not an expert at this sort of thing, what kid of washer can I use to stop the bolt from spinning? A lock washer? Should I use an oversized lock washer or lock and an oversized flat washer? I figure I can fish the new bolt through, put some 3M 4000 around the outside and tighten the nut to secure the swim platform and secure the biggest Transom weakness I see for now.

 

[dolfan1710]

Something like 3M 4000 would work, but you really need to get at the back side of the bolt to tighten it (assuming the wood isn't mush and the bolt can be tightened...). If you don't tighten the bolt, any sealant you put in there won't last long because the ladder flex and pull away the sealant.

The screw hole was mush, the head of the screw passed through it but the wood around it doesn't seem bad.

 

[dolfan1710]

I’m obsessing a bit. Here is a hammer test, think I have some weakness on the swim platform side (left) of the out drive. Wondering if it’s worth taking it out to see if it takes on water or not.

 

[JASinIL2006]

Hammer test is worthless. You have to drill holes into the transom (from the inside) and look for wet or dark wood (vs. dry, light shavings). Anything else is just a guess...

 

[dolfan1710]

Thanks JASinIL2006, I went through your restoration project thread and found it interesting, great work. I spoke to a guy at work who is also very knowledgeable. My next steps are to fix the swim platform bolt, take the boat to the lake and see if it's really taking on water. I've never seen it as this was discovered by the mechanic when I dropped the boat off for a no crank issue. My only worry is to stall and hit the no crank issue. Is there a way to start the boat in case of emergency assuming the starter and battery are good (the battery is good, I tested it yesterday).

 

[tank1949]

The screw hole was mush, the head of the screw passed through it but the wood around it doesn't seem bad.

If you drill out black mushy stuff, anywhere on stringer, motor mount, or transom, plan on repairs or eventually SINKING. Perhaps wait to winter...

 

[dolfan1710]

I was leaning towards moving on from the boat but a guy I work with is assuring he this stuff isn’t too hard. I’m worried about removing the motor. Not sure how to do that.

 

[dolfan1710]

Decided to have a surveyor take a look, he's coming later on today.

 

[GA_Boater]

Decided to have a surveyor take a look, he's coming later on today.

Dolfan - Moved this out of the M/C section to the Repair/Resto section so more members can offer advice about fixing the leak if you go that way. In the Mercruiser section the viewing audience was limited, although you are getting good suggestions, a few more eyes won't hurt.

 

[racerone]

Rotten transoms is very, very common.-----The most difficult thing is to convince folks that fiberglass boats often come with wood frames / stringers / transoms.-----Moisture and summer heat just eats the wood.----Working on replacing a transom right now on a 40 year old boat.-----Material in the transom could best be described as ---" beaver puke "-------Pockets under the floor with water logged foam.----No drain points in those pockets either.--Sad that there are few regulations / standards on small fiberglass boats.

 

[dolfan1710]

Moisture meter pegged, percussion overall pretty bad surveyor says DO NOT USE. Oh well decisions, decisions!!

 

[JASinIL2006]

Downside: if you fix it yourself, figure on 200-300 hours of work, $2000-4000 in supplies/tools, and a fair amount of frustration. Definitely doable if you are handy and motivated.

Upside: you will have a well made boat for less than you could buy one; you will know your boat better than you could imagine; and you will have a reason to fell proud every time you use it. And you will know it’s safe.

I never rebuilt a boat before, and even though much of the work was not fun at all ( e.g., grinding out fiberglass), I would not trade the experience for anything.