3M 5200 failed, transom most likely exposed to water

When I bought my boat a transducer mounting plate had been screwed on. I removed it and on the recommendation of everyone I talked to online and in store I covered the screws with 3M 5200 as well as the back of the board. Well today I was making some adjustments to my transducer and I noticed the right screw was a bit loose. I took the screws off and the board with the transducer fell off of the transom.

Has anyone else ever heard of this? The real crap of it is that I don’t know how long it has been like this and I am pretty worried that water has been getting into the transom.

Any recemondations for how to move on from here? A new sealant recommendation and new screws are what I am thinking. Anything I could potentially do for the transom? Heat gun or blow dry the area?

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First question, are you positive the transom wood goes all the way to the hull? Some wooden transoms only go about halfway down.

Also was there any moisture behind the board when you took it off?

Were these just screws or nut and bolts that went through the transom? Best to go with bolts and locking nuts for the mounting plate. Screws can eventually work their way loose. On the transom I replaced the wood did not go that far down into the transom but it was an old 16ft deep hull Starcraft.

Holy sealant, that’s alot.

Literally gonna be sealing EVERYTHING to do with water with 5200 on my boat tonight. Hope this isn’t an omen.

I have zero experience with 5200 but for an adhesive to fail like this I’d say there was moisture behind it to start? Is this possible?

I use Shoe Goo on all of my transom plates. Anything you put this stuff on will not be coming off. It’s amazing stuff. It will look like you just put it on 10 yrs later.

I wish you luck on this!

I had the same thing happen on a 16 foot Lund I just sold. I always used silicone and it held very good. I went back to using it. I do like the idea of shoe Goo. That is some bad stuff if you get it on your hands

Joe Scegura wrote:

I have zero experience with 5200 but for an adhesive to fail like this I’d say there was moisture behind it to start? Is this possible?

I use Shoe Goo on all of my transom plates. Anything you put this stuff on will not be coming off. It’s amazing stuff. It will look like you just put it on 10 yrs later.

I wish you luck on this!

What I am finding is that 5200 is more of a sealant than an adhesive. When I applied it the hull was clean and dry. I don’t remember how long but I think it was at least 48 hours of cure time on it.

When the board fell off it was moist (was on the water 1 hour earlier) but not wet.

Looks to me like both mating surfaces were not cleaned off properly.

Clean off the old sealant, wipe it down with acetone and sometimes less is more with 5200.

basseyes wrote:

Looks to me like both mating surfaces were not cleaned off properly.

Clean off the old sealant, wipe it down with acetone and sometimes less is more with 5200.

I did not use acetone or anything like that. Perhaps that was the issue.

5200 is 7 days full cure.

Their is a quick dry sealant as well, believe 2-3 days and is less permanent.

Adhesives and sealants like this I always worry about freezing and compromising the product. Not sure how 5200 is but products like this I tend to pay more knowing it’s taking care of prior to purchase.

How well was it adhered to the transom?

There should not be any transom wood that far down, so that’s one less thing to worry about.

If you can scrape/clean all the old sealant off.

Wipe everything down with acetone and make sure it’s clean, clean. Both the transom and mounting board.

Then put a thin layer on the whole board, fill the screw holes, then put the board on and move it around a little to get the sealant to adhere better. Then fill the screw holes from the outside of the board. Screw it in and be careful not to stripe the threads in the transom. If you do you can upsize screw size thickness. I personally prefer to wipe off all excess. Letting it cure is a big step dismissed. Once it’s cured, a thin bead around the outside of the board helps pushed in and worked in with a finger. Once again wipe it down before running a bead and thinner is usually better. If you can get to the back side of the screws inside the boat, some sealant on the screws can help, but if it’s done well isn’t usually necessary.

Good luck with it.

Thanks basseyes that helps.

5200 is not meant to adhere to transducer board without surface preparation

Starboard adhesion

HRG

HRG,
Is that meant to be a link? If so it’s not working.
Ron.

In looking at your picture, I would say that the 5200 held up to the hull just fine. It look to be, that it will be a job to clean the old 5200 off.

The issue was the adhesion to the back side of the board. Most of the hi-density polypropylene type transom-saver are very slick and do not glue well.

You need to rough up the back side of the transom-saver to give it some tooth for the 5200 to adhere.

rwilliam wrote:

HRG,
Is that meant to be a link? If so it’s not working.
Ron.

Thanks. I think it’s fixed now.

HRG

I’ve been using this stuff:

https://www.westmarine.com/buy/west-system–g-flex-655-8-epoxy-adhesive–15537087?recordNum=39

for more than just boat repairs. This epoxy is the real deal and actually works on more than fiberglass!!!

I need to ask why the need for 5200 on the board itself?

Just seal the screw holes and all would be well. Big board more screws. But the holes will be only thing wanting to SEAL??

Shannon and HRG are on track. 5200 is not necessarily designed to adhere to HDPE (which is what I’m sure the block is made of) and many other types of plastic. It will work to an extent, but not in the long term, like you’ve seen. It’s a great adhesive and sealant for wood, aluminum and fiberglass but a not-so-great adhesive for plastics. I work in the plastics industry and it’s hard to find good adhesives that hold up long term to plastic.

Your best best is to remove all the adhesive (if possible, 5200 is strong stuff) and through bolt the bracket to the transom in the holes you already have with 5200 shot inside the bolt holes to seal it up. Completely sealing behind the board is unnecessary if the bolt holes are sealed up good.

Edit: Nick beat me to it.

HDPE material is extremely difficult for any type glue or sealer to adhere to. The link provided by Hot Runr Guy is the proper and only procedure that will yield good results.

Lots of great advice!

My problem with any epoxy is if it’s not done properly it can have issue’s, then it’s harder to fix or remove.

For me personally I don’t like water getting between the board and transom, especially if a boat is used in freezing temperatures. It can start flexing from the freezing and thawing creating issue’s.

I’ve had zero issues on my board using 5200 and it’s been rock solid for almost a decade with hitting floating debris and pulling off transducers.

Bolting is still the best option, but hard for many to do or get at, with epoxy and then silicone in the holes.

Roughing the board up helps, but like others have said it’s problematic to get it to adhere. The tightness of the hardware is important and it has to be tight.

Another nice thing about Shoe Goo is it’s clear. I apply it generously to the back of the plate and screw holes. Once tightened a nice clear bead is seen around the outside. Hard to look more professional than that.

I’d remove that mess on the back of your boat and give this a try. I’ve installed well over a dozen of these plates and I think you’d be pretty happy with the results.

Joe Scegura wrote:

Another nice thing about Shoe Goo is it’s clear. I apply it generously to the back of the plate and screw holes. Once tightened a nice clear bead is seen around the outside. Hard to look more professional than that.

I’d remove that mess on the back of your boat and give this a try. I’ve installed well over a dozen of these plates and I think you’d be pretty happy with the results.

When I do another one might have to give that goo a try. Like the clear idea.

Well with some acatone I was able to get all of the 5200 off of my hull. Cleaned it up pretty good and tried the shoegoo method that was mentioned. So far so good. Boat won’t be getting wet until saturday so that should be plenty of time for it to all cure

I sealed up all my outside inlet outlets past Wednesday, the 5200 is still pliable on the edges. Seems it really needs the 7 days to cure.

Kinda sucks waiting around for sealant to dry when prime fishing is upon us. Worth the wait, I guess….

Good thread with lots of good information!