Manky gunwale

Flew · 16 Nov 2009, 02:24

I have a crusader 2 with a sycamore [I think] gunwale that has seen better days. I tackled the worst last year and replaced 2 short rotten sections and she started the season looking great but now one or two other little bits are not looking so good and there is a spot of rot setting in there. It seems the edges gets worn by the cover and hiking backsides rubbing off of the varnish, then the wood soaks up water like a sponge. She will go into the garage after the boxing day race for some TLC [again].
My options seem to be:

keep replacing bits
replace the whole thing [how easy or difficult would that be]
Replace the rotten bits and cover the whole gunwale in a strip of glass or carbon tape for hard wearing surface.

The varnish and wood elsewhere is good but the gunwale always seems a weak spot in the system. Any suggestions?
Cheers Chris
3300

sam293 · 16 Nov 2009, 02:29

i think the first question is how much varnish and what varnish did you use?

Flew · 16 Nov 2009, 03:04

2 coats of 2-pack and 3 of epithanes. Maybe need 10 coats on the gunwale as it tends to brush on thinly on an edge?
Chris

sam293 · 16 Nov 2009, 03:47

ahh your putting single pack poly over 2 pack epoxy?
that may be your issue of why its all coming off

Tim Gatti · 16 Nov 2009, 05:47

Hi Chris - sycamore is not the best of woods for gunwhales as it is relatively soft and prone to bruising and damp incursion which then, as you know, turns the wood a very unnactractive black in very little time. However, it does look great when set against a deep red mahogany deck, bends relatively easily and is easy to shape and is relatively light, which I suspect is why so many 12's feature it.

If it keeps getting damaged, one option would be to strip it all back to bare wood and start again - frankly, I'd use a couple of coats of low viscosity epoxy when the wood is warm to encourage penetration (but not too warm or it will gas and you'll get lots of little bubbles emerging from the grain). With the second coat I'd apply a layer of glass tissue (an extremely fine glass cloth like lens tissue) which will add to the surface strength and abrasion resistance. Make sure it wraps right round the gunwhale edge - and is well saturated by stippling with your resin brush, but don't work it too much or you will end up with a very hairy finish as the fibres can strip off the surface very easily. A few days later when its all completely gone off, sand it down well and then finish with three or more coats of one pot varnish. It should all blend in with your decks and the tissue will be virtually invisible. I've used this approach on a number of occasions and it produces an almost bullet proof finish. Providing your sanding gives the varnish a good key there will be no risk of it peeling off!

However, if you really feel the sycamore has had it, you could plane it all off and replace with something more resilient - but I'd only tackle that if you feel your joinery skills are up to it and you have a good collection of wide jaw clamps. If you build it up in sections you can, if needs be screw and glue the inner strips but the final capping piece always looks better if it's glued and clamped in place with no screw heads to hide and no tell-tale wooden plugs on show.

Hope that helps

Tim

Flew · 17 Nov 2009, 09:40

Thanks Tim,

Really helpfull advice, the glass tissue sounds the way to go. I think the gunwale is savable if scoop out a couple of short sections and graft in some new wood as before.

Cheers
Chris

sam293 · 17 Nov 2009, 04:32

just dont go mixing varnishes again, its never a good idea, if your going to use single pack, make sure you go back to bare wood again, or it will just recact and come off as before.

it does say on the tin for two pack stuff not to use over or under any other types of paint/ varnish

Michael · 17 Nov 2009, 06:35

If the wood is discoloured you should try Oxalic Acid on it. It effectivly bleaches it. Then revarnish. Try www.agwoodcare.co.uk

Phil Brown · 17 Nov 2009, 07:08

It doesn't sound as if it's the bond between coatings thats breaking down as it's getting through to the wood

Epifanes Clear Varnish should be fine over 2 pack, see below for the product sheet from Marineware

http://www.marineware.com/pdf/epifanes/MW_Epifanes_2_1_ClearGlossVarnish.pdf

If you use oxalic acid, neutralise with bicarbonate of soda ( or baking soda) and wash well before coating

chalky · 17 Nov 2009, 09:00

Be careful if you are tempted to replace the the whole capping piece as you will need a deep board with lots of wasteage. The black marks on the sycamore gunwales of 3232 always looked much better after drying out in the garage but they didn't have any soft spots....
I have never had a problem with using 1 pack varnish or paint over 2 pack. The local yard use Jotun's Ravilakk as it is quick drying, builds up quickly to a good finish and it is much cheaper than 2 pack!