Transom Hardware sealing issue

[CJK440]

I installed a swimplatforms platform 4-5 years ago. Followed the instructions to the letter especially when it came to drilling and sealing the underwater transom support rods. I used 5200 liberally in the holes, on the lags and between the rod and transom. Its solid, I have no issue with it but I looked at the hardware recently while prepping the boat for the season and noticed some concerns. I see the blob of 5200 above the rod looks shrunk and pulled away or perhaps after curing, when weight was put on the rod it shifted downward taking up the clearance in the bolt holes. The brown stain emanating out of the gap doesn't look good but for all I know its some organic growth (my lake gets pretty nasty with algae and zebra mussels and its slipped all season. Its all stainless so it cant be a rust stain. But with looking ugly I'm worried about water intrusion into the wood.

I'm wondering if I should disassemble and reseal but with it all glued up with 5200 could I do more damage, like tear out the wood where the lags are threaded into? Am I worrying about nothing because if I applied 5200 liberally the lag holes should be water tight regardless of what the outside looks like, even if the rod shifted a bit? Should I get some 5200 FC or other sealant and caulk around the area for piece of mind?

 

[dingbat]

Its all stainless so it cant be a rust stain.

Most grades of stainless steel, 316 is the exception, "rusts" when deprived of oxygen.
Given the situation, wouldn't be surprised at all the 5200 hasn't trapped moisture between the bracket and hull.

Am I worrying about nothing because if I applied 5200 liberally the lag holes should be water tight regardless of what the outside looks like, even if the rod shifted a bit?

5200 has a nasty habit of drying out and shrinking, causing leakage and entrapment of moisture. I avoid using it like the plague.

The proper repair would be to remove the the ladder. Drill the holes out oversized then fill with structural epoxy and allow to cure. Once cured, drill holes to the proper size for the hardware. Install the screws (preferably 316 stainless) using 30 minute marine epoxy on the threads to seal the connection. No other sealing is required.

 

[cyclops222]

I would never use lag bolts where water splashes up and wicks into crevices.
Why not S S nuts, bolts and washers where needed ? I use Silicone sealant. Silicone is very gentile, when pulled apart with a hair dryer, to loosen it up. Done it.

 

[CJK440]

I would never use lag bolts where water splashes up and wicks into crevices.
Why not S S nuts, bolts and washers where needed ? I use Silicone sealant. Silicone is very gentile, when pulled apart with a hair dryer, to loosen it up. Done it.

That's what it came with. I don't know where I would be able to access from the inside if I drilled thru for nuts on the inside.

 

[CJK440]

Most grades of stainless steel, 316 is the exception, "rusts" when deprived of oxygen.
Given the situation, wouldn't be surprised at all the 5200 hasn't trapped moisture between the bracket and hull.

5200 has a nasty habit of drying out and shrinking, causing leakage and entrapment of moisture. I avoid using it like the plague.

The proper repair would be to remove the the ladder. Drill the holes out oversized then fill with structural epoxy and allow to cure. Once cured, drill holes to the proper size for the hardware. Install the screws (preferably 316 stainless) using 30 minute marine epoxy on the threads to seal the connection. No other sealing is required.

Maybe the downrod didn't shift, the 5200 shrunk.

What structural epoxy do you recommend? Since I don't think I can gain access to the inside of the transom I need to use blind hardware. Still recommend a lag bolt but in 316?

How will a lag bite into the structural adhesive? Will plowing the lag into a hole like I did to the wood originally cause the structural epoxy to crack? Or do I drill just smaller than the bolt thread OD to get some thread bite and rely on the marine epoxy in the hole and on the threads to get the final engagement?

Lastly..... being slipped for 4-5 years like this what are the chances I find that even when drilling the transom oversize, the wood is wet.....

 

[MikeSchinlaub]

That's what it came with. I don't know where I would be able to access from the inside if I drilled thru for nuts on the inside.

I there's no way to fit into the motor compartment to do it, you'll have to pull the motor. Heat the 5200 up with a heat gun to help remove it, really hot. Then bolt it with silicone under the brace and inside washers.

I've seen platforms installed with like 30 washers stacked on each bolt because they come with long bolts. Don't do that. Cut the shorter or buy shorter ones. You could also just run the nut on the long bolts, but use antiseize if you do. Stainless tends to seize when it gets hot.

 

[briangcc]

There's one true way to find out if the transom is wet...disassemble. Those bolt holes will be very telling given the size.

 

[CJK440]

I there's no way to fit into the motor compartment to do it, you'll have to pull the motor. Heat the 5200 up with a heat gun to help remove it, really hot. Then bolt it with silicone under the brace and inside washers.

I've seen platforms installed with like 30 washers stacked on each bolt because they come with long bolts. Don't do that. Cut the shorter or buy shorter ones. You could also just run the nut on the long bolts, but use antiseize if you do. Stainless tends to seize when it gets hot.

I think the locations will be below the glassed in floor outboard or inline with the stringers.

 

[dingbat]

What structural epoxy do you recommend?

I used Marine Tex on all my hull intrusions

Since I don't think I can gain access to the inside of the transom I need to use blind hardware. Still recommend a lag bolt but in 316?

How will a lag bite into the structural adhesive?

Not sure why you used a "lag bolt".
Much more contact area (strength) using wood or sheet metal screws.
If I remember correctly, the ladder of my old boat was installed with #14 screws.
316 stainless "screws" are readily available

Will plowing the lag into a hole like I did to the wood originally cause the structural epoxy to crack? Or do I drill just smaller than the bolt thread OD to get some thread bite and rely on the marine epoxy in the hole and on the threads to get the final engagement?

Use recommended pilot hole diameters

Pilot ‎Hole & Drill Bit Size Chart | Fastenere.com

Drilling a pilot hole and need to know what drill bit size to use? Reference are charts for all types of self-tapping screws, including AB, B, A, and 25.

www.fastenere.com

 

[MikeSchinlaub]

I think the locations will be below the glassed in floor outboard or inline with the stringers.

That's a really bad spot. The foam under the floor will have soaked up any water that made it through and start rotting all the wood.

The absolute best option there would be to cut out the floor about 6-8 inches from the transom over where the bolts come through. Dig the foam out and add a little bulkhead to box off the foam.

Of course, it's a lot of work, and depending on how long you plan to keep the boat will determine if it's worth the effort.

 

[CJK440]

That's a really bad spot. The foam under the floor will have soaked up any water that made it through and start rotting all the wood.

The absolute best option there would be to cut out the floor about 6-8 inches from the transom over where the bolts come through. Dig the foam out and add a little bulkhead to box off the foam.

Of course, it's a lot of work, and depending on how long you plan to keep the boat will determine if it's worth the effort.

I know the holes I drilled were blind. Nothing went thru.

 

[CJK440]

I used Marine Tex on all my hull intrusions

Not sure why you used a "lag bolt".
Much more contact area (strength) using wood or sheet metal screws.
If I remember correctly, the ladder of my old boat was installed with #14 screws.
316 stainless "screws" are readily available

Use recommended pilot hole diameters

Pilot ‎Hole & Drill Bit Size Chart | Fastenere.com

Drilling a pilot hole and need to know what drill bit size to use? Reference are charts for all types of self-tapping screws, including AB, B, A, and 25.

www.fastenere.com

The lag is just what came in the kit. I would think it would have better pullout force into just wood than a wood screw but doesn't matter now.

A wood or sheet metal screw will self tap into "hard as steel" Marine Tex?