Advice on re-sealing P-bracket...

[MattS]

This year's winter maintenance "can of worms" is my P-bracket! I'm looking for a bit of advice on how to ensure the worms stay in the can! Boat is a Moody 336.

My question in short is: Can I simply re-seal around the P-bracket by pumping Sika 291 into the hollow in the middle until it fills the void between bracket and hull?

The additional context is below!

I decided to remove the various layers of primer and antifoul and take the P-bracket back to the bronze, so that I could re-prime it with some Primocon and then paint with International Hard Antifouling.



It taking off the various layers of old paint, I inevitably exposed some of the sealant around the perimeter of the bracket. Since taking the boat out of the water over 2 weeks ago, there has been water seeping out of the sealant at the aft end of the bracket. This indicated to that the sealant must be letting water in for it to be pooled inside.



I wasn't overly comfortable putting her back in, knowing that the seal was compromised - so I decided to dig it all out, clean it up, and put some new Sikaflex in at the same time as fitting my new transducer.

The assumption I made was that there would just be a shallow groove containing sealant around the whole P-bracket assumbly. This is the case along the longitudinal edges as shown in this photo - there is a shallow groove lined with gelcoat which seems easy enough to fill:



However along the lateral edges, I was expecting two flate faces to seal between. In fact, the bracket actually has a hollow within the curved shape - it is not constructed to be flat against the underside mounting surface of the hull. In removing the soggy old sealant from both the fore and aft ends, I seemed to pull out a load of also soggy sealant from the hollow in the bracket.

You can see the hollow shape of the P-bracket if you look closely in these photos:



I did find a previous report from a 336 owner about re-sealing the P-bracket, but the P-bracket design seems completely different to mine, which as far as I can tell is attached to the hull with four bolts (as opposed to being a design that penetrates through the hull itself).

This is the internal mounting of my P-bracket under the aft bunk which leads me to believe it is held on with the four bolts through the hull only



Is re-sealing this bracket as simple as pumping Sika 291 into the hollow bracket shape until it backfills enough out to completely fill the voids between bracket and hull?

Or have I now compromised the seal to the extent that I have no choice but to completely remove and re-bed the bracket itself?

 

[michael_w]

Take it off and start again, it's the only solution.

 

[Hoist]

291 is great stuff but the only way to be 100% sure is to redo.

I did the same on our 336 and because we were racing her I filled and faired edges of the P bracket in using marine filler.

Did not crack and looked beautiful

 

[MattS]

291 is great stuff but the only way to be 100% sure is to redo.

I did the same on our 336 and because we were racing her I filled and faired edges of the P bracket in using marine filler.

Did not crack and looked beautiful

Thanks - that’s interesting. Was the bracket on your 336 the same design as this?

From searching around it seems that some 336s were made with brackets that passed through the hull and were secured with epoxy / glass internally. Mine seems to be bolted on to the surface of the hull, with 4 bolts through.

Just to be clear - did you remove your bracket and re-bed it, or did you fill in around it in place with the filler?

 

[Hoist]

I did not rebed it. I should have made myself clearer.

It was the same design as yours. I suspect your's is a mk2

I stripped it back like what you have done however the sealant was intact.

I then covered up the part that was lower than the hull with marine filler accross its entire surface only leaving the arm exposed

 

[MattS]

I did not rebed it. I should have made myself clearer.

It was the same design as yours. I suspect your's is a mk2

I stripped it back like what you have done however the sealant was intact.

I then covered up the part that was lower than the hull with marine filler accross its entire surface only leaving the arm exposed

Ah ha - got you, thanks.

 

[MattS]

Take it off and start again, it's the only solution.

Are you familiar with this style of P-bracket at all? Any idea how it is usually bedded onto the hull?

My assumption is that the only penetration through the hull will be the four bolts, which should be individually sealed - do you think that's correct?

Given that the sealant around the perimeter of the bracket was clearly compromised, but I have not seen water ingress via the bolts, I am quite nervous about taking it apart without understanding what re-bedding it would involve. The bracket itself is incredibly solid.

 

[Hoist]

I have read your original post 3 times now and looking at the picture from the inside the only way water can penetrate the hull is through the bolts.

Whether water can flow in and out the hollow should not matter as long as the bolts stay water tight.

I never knew that the P bracket was hollow, and my filling was just somebody on a crazy quest to make a seriously slippery moody - not to seal anything

I think it would be extremely hard to compromise the seal of the bolts by picking at parts in close proximity especially when they are under the force of the secure bolts. You might be able to tear away the edges but not the important parts in my opinion

 

[MattS]

I have read your original post 3 times now and looking at the picture from the inside the only way water can penetrate the hull is through the bolts.

Whether water can flow in and out the hollow should not matter as long as the bolts stay water tight.

I never knew that the P bracket was hollow, and my filling was just somebody on a crazy quest to make a seriously slippery moody - not to seal anything

I think it would be extremely hard to compromise the seal of the bolts by picking at parts in close proximity especially when they are under the force of the secure bolts. You might be able to tear away the edges but not the important parts in my opinion

Thanks for taking the time to re-read and think about this - I have to say my thoughts were in line with this. I cannot see that the sealant around the perimeter of the bracket was there to do anything other than to fair the profile and prevent growth in and around the bracket.

 

[oldgit]

Remove and reseal. Especially the bolt holes.
Done the job on several boats due to bending various "P" brackets.

Personally used CT1.

 

[MattS]

Remove and reseal. Especially the bolt holes.
Done the job on several boats due to bending "P" brackets.

Personally used CT1.

My concern with doing this, when I've seen no evidence of water ingress via the bolt holes, is that I will end up disturbing any specific bedding that might have been done with epoxy / glass etc. I'm quite nervous to be taking the bracket off unless I can find some information or experience of this particular design of P bracket... so far I haven't been able to find any information / articles / evidence of this shape of p bracket and how they are meant to be fitted...