To epoxy sheath or not

[ian]

I am restoring a 20ft Mirador and would like any comments on the merits and or disadvantages of using an epoxy resin to sheath the hull,(can you epoxy without using glass matting),or should I just paint,(which paints,which epoxy system?) The hull is marine ply with two chines and in good condition, it will be used as a trailer sailer so would not spend all season in the water,lake use and coastal. I would appreciate any constructive comments.
Thanks, Ian

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[oldsaltoz]

G'day Ian,

My what a thin profile you have.

There are no disadvantages to epoxy coating ply other than the added weight, the advantages are that it will reduce water entry and rot as well provide some extra strength, no need to add any glass unless you consider she needs beefing up a bit.

Sand the area to be treated with a 125 grit paper, fill any voids or low spots with closed cell micro balloons and sand again the next day, apply epoxy resin with a roller and a mate right next to you with a long bristle brush and get him/her to tip off the roller marks as you go, work from the top down about a foot wide at a time with a half inch overlap. You should get a mirror finish; when cured [the next day] give a light sanding with a 200 grit, just to remove the gloss, apply an epoxy primer, spraying will give the best results. then another light sanding and check for any remaining voids, chips or other imperfections and fill/sand them.

A good polyurethane paint will provide many years of protection and look fantastic, best sprayed on, I like the International Interspray 900, and the resin I have used for many years without a problem is the West System Epoxy.

Tip: Take your time, read what is on the cans and get a copy of the manufacturers safety data sheet, get a good respirator / breathing mask, not one of the throw away paper things that look like a doctors mask, they are not good enough.
Look for humidity below 73%, don't start painting before 0930 or after 1430, too soon too wet, too late dew point.

I hope this helps, refurbishing a boat this size is a very nice little project and the end results can be very pleasing indeed.

Good luck with it, andavagoodweekend.....



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[William_H]

G'Day Ian The amaount of time and money you spend on restoring your boat is a personal choice. You may want a boat to get onto the water in at minimum cost or you may want a boat to show and have people admire.. I think there is a lot to be said for ordinary oil gloss paint over wood. It is very easy to repair scratches etc. and cheap and easy. If you want something spectacular then sure epoxy and urethane will give a magnificent finish so good you wo'nt want to use the boat for fear of damaging the paintwork. regards ole will

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[oldharry]

Why do you want to epoxy it? If you are wanting to preserve and stregthen an elderly hull, and possibly cure leaks, then epoxy paint wont do. It will just fall off again within a season or two. Strengthening or extending the life of the hull can only be acheived by sheathing it, and to do this effectively the timber has to be very dry - around 15% moisture content maximum - which is around the level of new plywood. There is also a real danger of the sheathing breaking away, allowing water in which will quickly destroy the ply as it creates ideal conditions for rot to get hold.

If on the other hand you are wanting to create a low maintenance paint coat, carefully applied epoxy will last a little longer than a conventional paint system, but again, because it is entirely waterproof, if water gets behind it, it will stay there with potentially serious results. Again the ply has to be very thoroughly dried out for succesful adhesion of the paint coat.

I would have thought that a trailer sailer is more vulnerable to knocks and scrapes (from personal experience) while loading and unloading - it just never goes right every time! You would have to be meticulous about sealing up any bumps or scratches to prevent water getting through.

IMHO its just not worth it - a good quality conventional system properely applied will last almost as long, be much easier to maintain, and will allow the timber to breathe properly.

I have seen the conventional 'Dulux' weathercoat system used very effectively - and is as good as new after 4 seasons use. It is now guaranteed for 5 years if correctly applied to a house..... though they might not honour that promise in the marine environment?

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[Birdseye]

Epoxy doesnt flex and move as much as wood does. No problem if the coating is thick and re-inforced. But straight resin doesnt have that level of strength so you are likely to find cracks developing. Once that happens, epoxy keeps moisture in just as well as it keeps it out, and so rot starts.

Am not a great one for tradition and/or wooden boats, but in this case I would stick to the old traditional finishes. OK they are work, but they are easy to repair and well tested.

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[ian]

Hi,
Thanks for the replies, I have been gazumped on my boat purchase but will be looking for something similar and the comments you have kindly posted are noted.
Thanks,Ian

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