spray varnish or waterproofing?

[chrisbitz]

I'm stuck in the hell of reducing damp in my boat, and took out some boards in my one dry locker, where I store my bedding..
it seems that condensation is running along the roof and dripping down onto the boards on the outside of the locker, between the hull and the locker.

[URL=http://s1381.photobucket.com/user/chrisbitz/media/boat/35276B6A-EFA4-4E2E-A4CB-9D5F56DA0193_zpstsinnuaj.jpg.html][/URL]

is there some sort of spray varnish or waterproofing I can spray on the back of the boards to make the drips carry on and run into the bilges, or would it be easier to replace the boards with foamex or something like that?

 

[Hadenough]

Solve the promlem while you have it exposed! I had the same problem and insulated most of the boat with this stuff.
http://www.acefoam.co.uk/?gclid=Cjw...CXSQu2VcM9_ANfQBqTsLGueOalyesSmfD2hoCSq_w_wcB
Glues on well with spray adhesive if you abrade and clean the fibreglass with thinners first. I used 25mm thick but the thinner stuff is cheaper. If you go this route PM me and I'll give you tell you how I went about it.

 

[pcatterall]

Or insulate the whole 'condensing area' some people use that camping mat/bed roll stuff.

 

[catalac08]

Or insulate the whole 'condensing area' some people use that camping mat/bed roll stuff.

I used camping mat about 10mm thick, two different brands on both hanging lockers (port and starboard). It reduced condensation but did not stop it. Parts of the hull that are carpeted get no condensation but obviously if run off from other area goes onto carpet then it will get sodden. I think poystyrene sheet or similar would be better than camping mat.

 

[Hadenough]

I used camping mat about 10mm thick, two different brands on both hanging lockers (port and starboard). It reduced condensation but did not stop it. Parts of the hull that are carpeted get no condensation but obviously if run off from other area goes onto carpet then it will get sodden. I think poystyrene sheet or similar would be better than camping mat.

Polystyrene is toxic if it catches fire! IMO the only material to use is closed cell foam, which is moisture repellant and you can get fire retardant. I have experimented with thicknesses from 5mm but there is no real benefit until 15 - 18mm. I used 20 or 25mm, Sometimes difficult if there is no space behind the panelling.
By the way don't bother with the "self adhesive" variety, believe me - it isn't!

 

[Scotty_Tradewind]

I fail to see what difference spraying any finish on the cold surface will do. Water in the atmosphere will tend to condense on it if it's cold.

We did this in our forepeak http://s725.photobucket.com/user/johnscottorn/media/SANY0229.jpg.html?sort=6&o=47

which is this stuff doubled up in thickness...... http://www.amazon.co.uk/s/ref=nb_sb...nsulation&sprefix=radiator+insulation,aps,262

held on with this stuff....... http://www.amazon.co.uk/s/ref=nb_sb...ld-keywords=thixofix&sprefix=thixofix,aps,439

before facing up with this stuff which was fixed to the sides of the boat with the battens of bendy ply glued again with Thixofix ... http://www.beersltd.co.uk/site/display/SF000420 after sealing both sides with a household exterior oil paint.

In the lockers beneath the settees we lined with camping mat as/catalac08

S.

 

[ghostlymoron]

Condensation is a hell of a problem. The cause is rise and fall of temperature and humidity (as you probably know). With the recent large variations in both in UK the 'backend' at our house (uninsulated floors and walls and unsealed polycarbonate sheeted roof) linking kitchen with coal shed and WC was absolutely saturated on floor and walls. The weather changed and the condensation disappeared. My boat is prone to condensation on the underside of the cockpit seats which drips onto the engine and into the bilge - I've pumped quite a lot out of the bilge today but it will return.
The only solution is insulation and it doesn't have to be all that thick - 5mm or so - to be effective against condensation but it does have to cover all surfaces and not have any gaps. Camping mats being closed cell construction are ideal and fairly cheap. Attach with contact adhesive (non-solvent preferably) or spray on glue if you like to get high.
I can live with the problem as I only sail in the summer but if I ever clear the engine room for a new motor, I'll take the opportunity to insulate. I suppose you could just do the areas where it is causing a problem and easily accessible.

 

[GrahamM376]

Just varnishing won't move the dewpoint.

I would be tempted to glue some battens on, maybe add close cell insulation (or any other non-absorbent type) between them and then board over. I've used self adhesive carpet in some lockers with good results - http://www.hawkehouse.co.uk/linings/self-adhesive-linings/p80-cream-self-adhesive-carpet-lining.html - but it won't solve your problem if glued direct to the grp.

 

[chrisbitz]

It seems I didn't explain very well..

The varnish is to allow the condensation to drip onto the back of the locker wood and run down into the bilges without making the wood damp.

I've insulated a lot of the boat with the closed cell self adhesive insulation from the people in portsmouth who do it.. (hawker?) But it's such a PITA that I'd really like to avoid doing it in a place that doesn't really need it.

I was asking if there a spray varnish I can waterproof the back of the locker wood with, or would it be easier to replace the wood with foamex or some other plastic sheet?

 

[SteveSarabande]

Painting it with epoxy resin will waterproof the wood.

 

[prv]

Painting it with epoxy resin will waterproof the wood.

Certainly will, but there must be something a bit less expensive that would work just as well.

Pete

 

[oldsaltoz]

We resolved a similar problem by first improving the ventilation and then using cheap stick on carpet tiles, now no condensation at all.

Good luck and fair winds.