Hull epoxy

04/12/2018 19:05:38
I have merlin 1267 and it is now stripped and sanded. Does anyone have experience of epoxying an old boat. It's been dried stored for 5 years so pretty dry. Our local agent for wests was concerned of planks moving as we step around the boat.

Should I do inside and out or neither? 

Thanks
Richie

04/12/2018 20:00:36
Rod & Jo
I think your agent is being honest.
 
Epoxy & old wood will only mix well if the epoxy can soak thoroughly into the thoroughly dried out wood & you are 100% sure nothing will move & new moisture can't get in anywhere. Mention of planks moving suggests this might not be the case & if so you would be headed for BIG trouble.
 
I have just restored a 1961 Vrijheit,- strip planked SIPO hull , where strips were 'mobile' and one could even see daylight. In that case I put an epoxy/glass skin on the outside to hold everything together (difficult if not impossible on a clinker hull), but the strong advice from the Dutch boatyard who deal with a lot of these old boats was to treat the inside with Linseed oil so that it can still breathe openly.
 
If your clinker planks are actually moving, the only real solution is to stop that by scraping out old glue, injecting new etc. possibly using mechanical fixings to stabilize.
 
If the concern is not that the planks ARE moving, but that they might or could, I would still stay away from epoxy;  at least on both sides. Traditional varnish finishes have better 'breathability' 
 
R&J 

04/12/2018 20:47:02
Tim M
Assuming the construction is glued plywood (most likely given the sail number), there shouldn't be any issue with epoxying the joints both inside and out.  Apply a sheathing of epoxy which covers the totality of exposed wood is something I have seen but on reading more on the subject, sounds like a potential recipe for disaster if any water gets in (it stays trapped and rots the wood).
 
I'm also about to start work on a vintage Merlin hull and will invest the time to strip the varnish from both the outside and inside.  More importantly, I am going to strip back the varnish from the glue joints to expose bare wood and then run a small seam of epoxy down the joint on both the outside and inside.  I won't epoxy the whole plank.
 
I'll also have a bottle of penetrating glue (like ZAP CA) handy in case there are any fissures that need plugging before the epoxy seam is applied. 
 
In order to reduce this labour of love a little,  I am probably only going to do this for the seams of the planks in the floor (probably the first four on each side).  I will also design some strengthening beams which will help to strengthen the floor where it is pounded by the crew and helm.
 
You should find that there isn't too much need to get into the hull during this process.
 
 The planks will then be coated in a one pack varnish which will be tough and adequately good looking (I am going to sand the varnish smooth anyway so aesthetics will be compromised by that process).
 
Hope that viewpoint helps.  If you are on Facebook, join the Merlin Rocket Revival Fleet group, they love this type of subject! 

04/12/2018 21:36:43
Chris Martin
I'd use something like eposeal (excellent penetration but pricey) as a primer, but I dont think I'd resin coat it. I think it'll be too hard once you've achieved any kind of build and might crack.
 
The trouble these days is finding a one pack varnish that will overcoat in less than a week in summer, at this time of year I dont think you stand any chance whatsoever without significant heating. If you've gone to bear wood and eposealed the hull you'd be ok with a two pack system and that will dry. It will be quite hard but I doubt think you'll crack it on a glued hull indeed a younger wide boat will have been done in two pack from new.

05/12/2018 08:13:02
Chris Martin
Thinking about this a little more GP14s, Ents and Solos have been routinely coated in epoxy inside and out for decades. They have far wider panels than any Merlin and ive never seen one of them have any issue with an epoxy coating cracking.
 
So on a glued clinker boat, why not?
 
I think you would have to be extra careful to remove all of the previous coating and get it absolutely dry. I'd definitely use eposeal first as the 320 will stick to it better than the bare timber (Which will inevitably have some residues on it).
 
The only problem I can forsee is as Rod says if you get a problem later on you may make it harder to dry out - again, this doesn't bother the Ents GPs or Solos. 
 
If you need to do this your main enemy will be adhesion due go previous coatings. 

09/12/2018 16:13:49
Rod & Jo
My comments were specifically about what I believe is a poor mix of old suspect wood & epoxy. I have no issue with epoxy on new wood, nor on old solid if you can be sure it is properly dry & clean & can soak up the epoxy to get a key & form a solid joint, nor even on old fragmented wood, with the same provisos. The problem is in inaccessible places of uncertain condition which might or might not be moving & where as Chris says correct adhesion can be an issue. The last thing you want is to have an iffy joint with moisture sealed in by epoxy on all sides, this leads to trouble.
 
 

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