2004 - 180 Sportsman Transom, Reason for Concern?

Recoil Rob

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The boat has been trailered all it's life, the transom feels and sounds solid, no flex at all. But there is some corrosion/expansion going at the very top of the port side by the aluminum trim.

Reason for concern? What should be done?


thanks,

Rob

IMG_9836.JPG
 

Fishtales

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The trim piece is called the bang plate. The hull and liner joint is under it. You can take the engine off and replace the part (it is a white phenolic or plastic piece on new boats) if desired. If you do this, you should check the joint and either glass it over or ensure the joint is tight before re-installing. The piece is largely cosmetic but it protects the transom when the engine is installed. There are screws that hold it in place and the joint is under it. If you don't want to take things apart, you could tape off the edges and caulk all edges as well as remove each screw, caulk and re-install.
 

seasick

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I can't tell if the aluminum bang plate has shifted up or if the outer edge has just corroded away. This may not be serious but does indicate that moisture has or will get under the bang plate. That moisture may or may not soak into the transom.
If you tap the bang plate, can you see it move up and down? If so, you need to decide if you want to open things up and that will mean lifting the motor. If it seems solid, for now you can sand/grind away the corroded edge to clean it up and seal with a good caulk like LifeSeal.
Down the road, a moisture test will document if and and how far any water has penetrated the transom coring.

It is a good sign that the motor mounting bolts are not oozing rust stains. That tells me that the transom, at least behind those bolts, is probably dry.
 

Recoil Rob

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OK, thanks for input guys. I was hoping to not have to lift the engine as I don't have a lift. I think I'll lift the aluminum and see what's going on underneath and then grind and seal with LifeSeal or 5200.


thanks,

Rob
 

seasick

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do not use 5200. That stuff is primarily an adhesive not a sealant per se.

I don't think you can lift the aluminum without lifting the motor. Check first to see if it is moving up and down when you tap it. If not loose, just resael it.
In theory the cap does not need to be 'glued' to the transom. The only reason to put something on the transom edge is to seal the core. Epoxy resin is the best approach but the cap needs to be off. The aluminum cap is usually mechanically attached with screws and then sealed along the edges to keep splashed water from seeping under it. The screws should be coated with someting like lifeSeal, 4200 or even a dab of 5200. The purpose is to block moisture from seeping under the screw heads and onto the threads.
 

DennisG01

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It "appears" that there may be some expansion/bowing of the transom. It's conceivable that because the bang plate hasn't been re-sealed on a timely basis that it has allowed water into the transom and the wood has swelled. But obviously I can only base this on that single picture. Either way, I do think there's enough of a concern to warrant lifting the engine off and checking things out further. A number of exploratory holes could be drilled into the transom at various spots to check the wood quality, too (and the engine wouldn't have to be lifted for that).

You don't need a lift to pick the engine up... got a tree nearby? How 'bout a neighbor with a pole barn or a high patio or something similar? Where there's a will, there's a way.
 

seasick

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Although the hole method will show if there is significant water, shy of drilling a lot of holes, it doesn't tell the extent of the problem.
Have excessive moisture in the top inch or two of the transom edge is not all that serious whereas excessive moisture from the top edge halfway down or more is cause for concern. Of course rotted/soft coring is an issue if more than the immediate top edge of the transom core.
Once again, I would go for a moisture meter test by a knowledgeable person to see what the story is.
As I mentioned in a previous discussion, a hollow core will read zero moisture but in that case, the tapping test can be used to listen for voids.
I was not able to tell looking at the photo if the transom was swollen or if the there was just corrosion growth on the edge of the cap. I would try scrapping that edge to see if the laminate looks good and if it is flat or bulging.
 

DennisG01

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I was not able to tell looking at the photo if the transom was swollen or if the there was just corrosion growth on the edge of the cap.
It may not be swollen - it just appears that way in that (single) picture. A straight edge along the transom - then comparing to the other side for good measure - may be helpful.

"Core" samples would show if the wood was wet, though. If there's access, it can be done on the inside to make repairing very easy. A moisture meter is a good idea, too.
 

seasick

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Sorry to beat this to death but I was trying to explain that if the core rotted away or opened up in voids, those spots will not read high moisture even if the void were fill of water. There has to be some sort of 'solid that has moisture in it for the meter to detect moisture.
I was tempted to go out and get one of those General moisture meters that was shown in this thread but I am not convinced about how effective it would be. Time for some research. I am more familiar with the Tramex but I don't own one. It was tempting years ago but to spend $500 now on it might get me thrown out of the house!
My concern about the General is that most meters designed for sheetrock or lumber penetrate only about 1/2 inch. The Tramex reads a depth of about 1 1/4 inch. Hulls and other marine panels are typically thick
 

seasick

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OK, I am hooked on learning about moisture readings. I just read an article that did a group of tests on cored and solid fiberglass panels using a typical pinless moisture meter designed for wood products.
The most interesting fact was that if you use a construction style of meter, a moisture reading of 30% in wood is equivalent to 3% reading in a solid fiberglass panel.If that is true then Rob's deck may be fine.