Soggy deck advice...

[winsbury]

The sole of my cockpit deck has delaminated and gone soft over about a foot square where some plonker has removed a deck fitting but not plugged the holes sufficiently thereby allowing water into the core. I decided against trying to inject epoxy in the holes and from inspection below it was obvious someone has already tried in the past drilling numerous holes to let it drain without success. So, I've removed the grp from below and cut out the rotten plywood leaving only the top grp skin of the deck in place. I planned to epoxy in a new piece of marine ply and cover with fresh glass mat once it had all dried sufficiently. The problem is it simply isnt getting dry - I dont know if its bilge water condensing from below or whether water is seeping in from elsewhere but three weeks on and there is still water appearing around the edge of the good wood and the bottom of the grp is wet to the touch. I dont think the cold weather is helping but any advice would be appreciated - perhaps a heater or dehumidifier might be needed but is it even worth trying in the sub zero temperatures at the moment ?

 

[neilf39]

Maybe condensation. Do you have good air circulation below? You may need to use a dehumidifier or cover the boat so you can open the hatches a bit.

 

[winsbury]

Circulation is definitely an issue - its the hold below the cockpit so virtually no airflow unless I open the deck hatch which in turn lets the rain/snow in. I'll see if I can prop the lockers open a bit which should help.

 

[macd]

Winsbury: is there any sign of osmosis in the remaining GRP (vinegar smell is a good giveaway)? If so, osmosis products are hygroscopic, so will never dry if there's any humidity.
Equally, it could merely be salt ingress into the surviving GRP -- salt, of course, also being hygroscopic.

So, paradoxically, to dry the GRP you need to repeatedly and vigorously wash it to flush out the hygroscopic elements.

Not saying this is why your particular job isn't drying, but worth checking out.

 

[Deleted member 36384]

.... So, paradixically, to dry the GRP you need to repeatedly and vigorously wash it to flush out the hygroscopic elements.

Not saying this is why your particular job isn't drying, but worth checking out.

In a similar manner dirt and grime attracts or rather retains moisture. A good wash in fresh water fallowed by a scrub with hot water and a cleaner and rinse off would not go amiss in helping to prevent moisture build up and retention.

 

[pcatterall]

Clearly the area of exposed single thickness grp will be the spot where moisture will now condense. Yes removing muck and salts may limit this but not stop water condensing and making the ply wet.
Cover up that area with some temp insulation just to prove that it IS condensation making the wood wet and NOT a leak!! Once your sure you only have to get it dry long enough to effect repairs. Good dry heat for an hour or so should do the trick but obviously no excess retained heat when you start with the epoxy!!
Perhaps get the ply dry and start with a thinned epoxy to seal the ply?

 

[oldsaltoz]

Sounds like you are trying to do a job at the wrong time of year. Consider adding some spray foam to temporarily reduce the condensation and give yourself a break.

The area needs to completely dry before any attempt is made to repair it properly or you will have the same problems the last attempt has left you with.

A little planning saves a Lot of time and effort.

Good luck anf fair winds.

 

[winsbury]

Many thanks for all the replies and some good ideas..

osmosis: no vinegar smell and hull has already been treated plus this area will well above the waterline so dont think its that.

dirt and grime - yes this is present, its far too cold to wash it at the moment but will do.

wrong time of year - given the weather we've had this year I'm not entirely sure there has been a right time but I take your point, that said there have been a few warmish days when everything else has dried off.

condensation - this is my guess too but its not occurring elsewhere but perhaps that is indeed because its now single skin so will try covering with some insulation from above and see if that helps. Ive also held the lockers slightly ajar now to allow air to circulate round the bilge more more freely.

Salt - not much chance - its been on fresh water for the past 10 years. My project is all about getting the boat back into shape to go to sea.

take a rest - hmm - about 50 other jobs still need to be done of various complexities so while I could really do with a rest and this job done too, its not a desperate panic if it takes a while to dry out, its just that I thought it would have done so by now.

Thanks again.

 

[lw395]

If you have mains electricity, gentle heat, e.g. couple of lightbulbs will work wonders, but it takes time. Weeks for water to work its way out of the wood.
Getting all the water out of the boat and keeping the whole thing dry is important.
Every drop of bilge water that evaporates will want to condense on that cold single skin.
A dehumidifier and seal the boat up is one option.
The other is heat and ventillation.
Covering the boat as much as possible, plus a small heat source will make a difference.

 

[Boathook]

If you have mains electricity, gentle heat, e.g. couple of lightbulbs will work wonders, but it takes time. Weeks for water to work its way out of the wood.
Getting all the water out of the boat and keeping the whole thing dry is important.
Every drop of bilge water that evaporates will want to condense on that cold single skin.
A dehumidifier and seal the boat up is one option.
The other is heat and ventillation.
Covering the boat as much as possible, plus a small heat source will make a difference.

Agree about the gentle heat. A tubular heater is very good and can be left on for long periods. Not to sure where the OP is based but the temperature for GRP work is to cold at present without protection and heat.

 

[oldsaltoz]

Agree about the gentle heat. A tubular heater is very good and can be left on for long periods. Not to sure where the OP is based but the temperature for GRP work is to cold at present without protection and heat.

Precisely, that is why I suggested leaving it till conditions improve.
A lot of the work I have done for clients is fixing up failed glass work that was carried out in less than ideal conditions.

It seems the OP has a lot of other tasks to clear so hopfully they can given priority till conditions improve and avoid delays in getting her back in the water safely.

Good luck and fair winds.