This is why you dont use pressure treated wood!!!

Bought a 12' monark - upgraded from a 10'er. The PO used a PT transom and now I'm unsure if this boat is salvageable.

What can I do about this??

Ouch and without knowing a lot more or seeing more pics, can't help but indeed NEVER use PT wood!

Should I begin by sanding all of that off?

JRyno10 said:

Should I begin by sanding all of that off?

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That or wire brush.

My boat ha PT wood on the bottom deck the guy I got the boat from told me he put it in so that is the number one reason I took my apart to remove that stuff plus it weight about a 175 pound for a 55 1/2 x 39 piece of water logged wood so about 350 pound of wood just in the bottom deck in my boat. Thank god it had not been in there but one hunting season.

I meant to say wire brush, i think i will epoxy or jb weld a new piece of aluminum to the transom.

Use phosphoric acid to clean and neutralize the "sugar" that has formed on that aluminum. Then, inspect the amount of corrosion, if there are only a couple of holes, those can be either welded, plated, or filled with something like ce-ram grout (ceramic-based epoxy used for this type of work) Once the repair is done, it should be primed with zinc chromate, then painted with a good epoxy primer such as interprotect.

My entire transom was badly pitted and it had way too many holes to be welded. I opted to have a piece of 1/8" aluminum that covered about 90% of the transom welded to the original. The wood on mine was too far gone to know for sure but I suspect it was PT wood that was used and caused all the pitting.

I appreciate the responses. PSG- I will most likely do that tomorrow. I am just wondering if this boat is to far gone and should just get rid of it?

It's hard to say without looking at the boat. But if the only area of corrosion is the transom, it's definitely worth saving.

Heck, take a look at my jetboat, the bottom was badly corroded, and it was destined for the scrapyard. And here it is, several years later, I've taken that boat to places I would never dream of taking a regular boat!

That said, if the majority of the transom is FUBAR, then you might want to make a new transom out of some 1/8" aluminum plate. If I were going that route, I'd take out the old transom, clean the seams really well, and weld the new one in. Also, if you use the proper cross members made from square, or better yet, rectangular tubing, you don't even have to mess with plywood. For instance, putting a piece of 2x4x1/8 rectangular aluminum tubing across the top, which gives you an attachment point for the motor. Then some vertical stringers that are welded to the bottom side of that tubing, and run all the way to the floor.

I will post some pictures of it here in a minute

This is after i cleaned it up a bit, got about all i could get off.


Here are some close ups on the worst parts.

Top left


middle section


top right

Yeah, that's some pretty extensive corrosion damage. A lot of deep pitting, with some of it going all the way through. If the corrosion is only like this in the center, where they had the plywood, you might be able to just cut out and replace that part, or, if you're not comfortable with cutting it out completely, at the very least, fish-plate your new piece over the top of it.

If you decide to cut out the old damaged section, to keep the existing transom from warping when you cut it apart, go to either side of the section you're going to remove, and attach some type of bracing, such as tack-welding some aluminum tubing, as vertical stringers.

Once you cut out the old part, cut your new piece, large enough for a 2 inch overlap on both sides, and weld it in place. Then weld some cross members to it, tying it in to the bracing you previously welded in place on either side of the cut-out.

I agree, don't use PT but, your transom doesn't look all that bad. Here is what I did and it is solid as a rock.
I used the G-Flex epoxy which is a thick putty type epoxy.

I also would suggest you get a stainless Steel wire wheel for your drill. It will do a mush better job than a SS wire brush. Use SS not carbon steel! I wouldn't cut any of that out.


https://www.tinboats.net/forum/viewtopic.php?f=3&t=23064

WIRE BRUSH IT GOOD CLEAN WITH ACID. YOU COULD THEN CUT A NEW PIECE & USE AUTOMOTIVE PANEL BOND TO GLUE IT ON TO OLD PIECE.

zipperer said:

WIRE BRUSH IT GOOD CLEAN WITH ACID. YOU COULD THEN CUT A NEW PIECE & USE AUTOMOTIVE PANEL BOND TO GLUE IT ON TO OLD PIECE.

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If your going to glue a piece over the old use 3M 5200.