hull deck joint resealing

[allweather]

This winter I want to fix an issue with my H-boat I always postponed or temporarily adressed ever since it came out the yard with a new paint job. This time for good.

Yard painted both hull and topsides seperately and then sealed the small gap where coaming meets the hull with some 3M. Which worked but only lasted a few years. Redid it once and used some lesser compound so it lasted an even shorter period.

My plan is to remove all the sealant, let the boat dry over winter in case there is any moisture at all(unheated warehouse), and then run a bead of thickened epoxy in spring for a lasting seal.

My question is if there are any obvious pitfalls I should be aware of and if using only one epoxy is a viable idea or if I should accept that I'll need to paint it afterwards for UV resistance? I still do have a small bottle of the 2k paint used for both the hull and top sides.(occasional scratch repair)

Doing a second pass shouldn't be that difficult since while going around the boat is quite some distance, the area that would need scuffing is ultimately small. More pain redoing the masking tape and later polishing than anything else.

 

[slug zitski]

Use UV resistant caulking 

Sika... can’t remember the number ...UV 

if this is simply a cosmetic bead of caulking ...teak deck systems .. TDS deck caulking is UV resistant and available in most marine stores 

 

[SloopJonB]

Sluggo is right.

Unlikely that you will get a seam that had goo in it clean enough to take epoxy properly.

 

[Ishmael]

Use UV resistant caulking 

Sika... can’t remember the number ...UV 

if this is simply a cosmetic bead of caulking ...teak deck systems .. TDS deck caulking is UV resistant and available in most marine stores 

Sikaflex 295 UV.

 

[allweather]

Pretty unanimous for simply using sika295uv then.

Kind of hoped for a different outcome, but advice has not steered me wrong here yet!
Besides that was probably what they used the first time around and it was my mistake to take off the shelf  sika that led to early degradation.

Going to post pics when the boat is out of the water and I've started removing the old crap. Until then I want to ask about opinions about bead... width?
Personally I'd like to go for a small radius, say 4mm.

Save myself some additional work and material. Also wondered if I could then just run another bead on top with a larger radius, 10mm, once the first one starts degrading so that I only need to deal with removal every other time.

 

[JMOD]

an overlooked detail, that can make a lot of difference to the durability of the boat. Replace the sealants every couple of years. also check the sealants at the hardware.

 

[allweather]

also check the sealants at the hardware.

How would I do that without removing everything?
For reference, I do keep an eye on moisture as well as stains or the like to find any potential leaks (also no sandwhich core on the boat, just full laminate). And it is all bone dry since I redid the V-berth hatch.

 

[SloopJonB]

Also wondered if I could then just run another bead on top with a larger radius, 10mm, once the first one starts degrading so that I only need to deal with removal every other time.

Attempting to stick any sort of adhesive to a degraded surface is a recipe for failure.

As a short term bodge to get out of a jam, O/K but otherwise?

 

[allweather]

Just to be sure, no go to have a larger fillet that overlaps enough to also touch 2-3mm pristine hull? The hard way it is then...

Though I am still considering to clean up the "crack" with epoxy and then add the fillet with Sika afterwards. Is there any reason why epoxy could be an issue? UV stability aside.

Bit difficult to explain until I've opened up the joint and took some pictures. But right now the actual, not watertight, gap is 1-2mm wide. I'd like to seal that with epoxy(no fillet) so that just in case the sika ever fails before I got to replace it the area would still be watertight.

Reasonable or idiotic idea?

 

[SloopJonB]

As noted upthread, you are unlikely to be able to get the joint clean enough for epoxy to bond properly. It like virgin surfaces.

Pics of the joint would help.

 

[allweather]

Pics of the joint would help.

I'll provide those. Boat will be lifted end of october and removing old sealant as well as dropping the rudder will be the first tasks.
Until then I already have a roadmap on what to order.

 

[IStream]

I don't know, I think that if you ran a carbide ball or some other abrasive of the appropriate shape for the gap in question, you could expose enough virgin surface to get good epoxy adhesion. If we were talking about a hull-deck joint that was leaking into the boat, it's absolutely the way I'd go. If we're really just talking about filling a deep channel, it would be a lot less work just to run a bead of sealant but with an abraded surface, I think the epoxy+paint solution would be a good one and a lot longer lasting even if it's more work up front.

In either case, some pictures sure would be a good addition to the thread.

 

[Leeroy Jenkins]

Sikaflex 295 UV.

I think the OP is in Europe, maybe tell him the metric equivalent? 

 

[allweather]

maybe tell him the metric equivalent? 

Whatever do you mean? I can get Sika 295UV 20Euro a cartridge here.

 

[SloopJonB]

 

[SASSAFRASS]

Sika used in conjunction with the sika primer and proper prep is a very effective long term goop.

TDS white is also very resilient, more flexible and holds it's color better than most.

 

[Crash]

So your talking hull-to-deck joint, but only talking about replacing the sealant bead on the exterior of that joint?  Do I have that right?

If so, I'm not sure you can ever "fix it for good" without lifting the deck clear of the hull, cleaning all the old goop off, and starting new.  That, of course, would be a "HUGE" project.  But no amount of replacing goop (no matter how great the goop is) on the outside of the joint is going to permanently solve the problem.  You face a choice of goop every couple of 5 years or so, cleaning everything to be spotlessly clean and glassing the joint with epoxy (then re-painting), or opening the actual joint and redoing it - which as mentioned, is a HUGE undertaking...

Or, living with a small leak or two...  

 

[Alex W]

I resealed the hull/deck on my previous boat (a Pearson 28-2) with butyl (from Maine Sail) after reading that c&c used it. It worked great for the time that I owned the bot and solved a bunch of leaks that I had. 

I think butyl’s lack of drying out and ability to bridge big gaps works well in this application.  It’s not perfect for all applications.  
 

My current boat has a glassed hull/deck joint with tape and epoxy around the interior and maybe exterior. I think that would be hard to retrofit. 

 

[slug zitski]

Just to be sure, no go to have a larger fillet that overlaps enough to also touch 2-3mm pristine hull? The hard way it is then...

Though I am still considering to clean up the "crack" with epoxy and then add the fillet with Sika afterwards. Is there any reason why epoxy could be an issue? UV stability aside.

Bit difficult to explain until I've opened up the joint and took some pictures. But right now the actual, not watertight, gap is 1-2mm wide. I'd like to seal that with epoxy(no fillet) so that just in case the sika ever fails before I got to replace it the area would still be watertight.

Reasonable or idiotic idea?

Use caulking 

if there is movement in the joint epoxy will fail 

if you go with caulking use a beading profile  tool

i prefer the  45 degrees profile  over a quarter round for longevity 

the quarter round is to thin for exterior joints