Bulkhead tab repair

[PaulGS]

My 1970's cruiser evinces a typical (according to the owners' association) parting of the ways between a bulkhead and the deck. This movement has been arrested by a steel brace to fix the chainplate responsible. I'm left with a residual 1-2 mm vertical gap between the bulkhead and the original fibreglass tab. Although there's hopefully now no absolute structural necessity, my thought is to simply push FG mat up into the crack to make good. But I'm pretty ignorant of boat repairs and so wonder if there might be a better option?

 

[Stemar]

No expert but, having done a bit of GRP work and watched a lot of YT videos, I'd be more inclined to go with an epoxy thickened with cotton fibres or silica (don't breathe the dust).

 

[PaulGS]

No expert but, having done a bit of GRP work and watched a lot of YT videos, I'd be more inclined to go with an epoxy thickened with cotton fibres or silica (don't breathe the dust).

Thanks Stemar. YT will be my next stop. The kits I've seen contain either epoxy or polyester resin - I imagined stuffing the resin-soaked mat into the crack.

 

[Trident]

Epoxy is always better for repairs as it sticks better - try to clean the gap with a bit of sand paper and acetone , then add epoxy thickened with milled glass or silica as noted above - mix epoxy and hardener together and then add the filler and mix to a peanut butter consistency and work it in with a lolly stick and an old plastic credit card type thing if you have one

I would also then bridge the gap between the fill and the original material with a strip of GRP - easiest is to buy a small roll of GRP tape maybe 2 inch wide (depending on the gap) . If the amount of gap is not too big you can do it with normal unthickened epoxy straight away. If there is a big volume of thickened epoxy let it set first, then clean off the top with a light sand and acetone again and do the second stage . The reason being epoxy is exothermic and big build up gets very hot

On that note mix small amounts of epoxy as you need it and try to use it in a flat tray if you've lots to do - lots of surface area to bleed heat rather than in a skinny cup which may get very hot very quickly. Also, if its not a problem how long it takes to dry then use slow hardener in this hot weather - will go hard in maybe 12 hours but the fast will set off in very short order , getting hot as it does. Its not scorching this week but in high heats I've been up to start work at 4.30 am to be cool enough to keep fast epoxy from setting before I've finished a job that may only take 30 minutes.

Also, wear gloves and a mask, don't take it lightly. Most people are fine with epoxy but some develop a sensitivity that means even a smell of it could kill - don't start down that road by letting any get on your skin or in your lungs ever.

 

[chriscallender]

Thanks Stemar. YT will be my next stop. The kits I've seen contain either epoxy or polyester resin - I imagined stuffing the resin-soaked mat into the crack.

Keep in mind that normal chopped strand mat is held together with a binding agent that dissolves when you wet it out with (polyester) resin. So it would fall apart. Woven mat and epoxy might allow you do do what you are planning, but I think this will still be an extremely messy and not very strong way of fixing it. If you have good access maybe you could bolt the tab to the bulkhead... you would probably need some kind of backing plate (eg stainless flat bar, or epoxy coated ply) on the outside of the tab. Then you can pull the gap closed as you tighten the bolts. Kind of hard to know/visualise it without photos though.

If its just for apprearance then I agree with the comments just to put thickened epoxy in there (or just leave it alone if it isn't structural and you can't see it easily!).

 

[Tranona]

Agree with that. Epoxy with silica to fill the gap then glass tape with unthickened epoxy. 1-2mm gap is tiny and milled glass will be too thick in the filler mix.