# Protecting marine-ply



## DomValente (5 Mar 2006)

I have been asked to make a storage locker out of marine ply for a friends boat. This craft is sea going although it spends most of its time on the Thames.
Does anyone have recommendations for the best protective covering,preferably not a gloss finish unless absolutely neccesary

Dom


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## Sgian Dubh (7 Mar 2006)

Is there a reason that a long oil, soft and flexible spar or marine varnish with UV blockers couldn't be used Dom? I assume these things are outside in all weathers and would need sanding and re-finishing every year or so---- as seems to be the case with most exposed wood on boats. 

I'm not into boats at all, but it's my understanding that maintenance of the exposed wooden parts is pretty much continuous. Slainte.


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## Unlucky Alf (7 Mar 2006)

Sgian Dubh":1qn7d1dx said:


> it's my understanding that maintenance of the exposed wooden parts is pretty much continuous. Slainte.



It is a never-ending chore. We've had good results with the "International" range but I think that all of their varnishes are gloss. They have good UV resistance, which is the biggest problem. I wouldn't advise using anything that is not specifically designed for a marine environment, it just doesn't last.

http://www.western-marine.com/page75.htm


I have heard some very positive comments about Sikkens Cetol marine, which has a satin finish, but I've never used it myself so I can't really offer any advice or recommendation.

http://www.yachtpaint.com/UK/sikkens/default.asp

http://marinestore.co.uk/page/mrst/PROD/varnishes---all-types-international/SOIVA300-750/

HTH

regards,

Simon

Edited for sp


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## Chris Knight (7 Mar 2006)

Dom,
I would use epoxy in conjunction with a compatible finish - the following is lifted from the West System site ( cant seem to link to the page in question.

QUOTE
Coating types

Latex paints are compatible with epoxy and they do an adequate job of protecting the epoxy barrier from UV radiation. In many architectural applications latex paint may be the most suitable coating to use. Their durability is limited.

Alkyd finishes-enamel, alkyd enamel, marine enamel, acrylic enamel, alkyd modified epoxy, traditional varnish and spar varnish-offer ease of application, low cost, low toxicity, and easy availability. Their disadvantages are low UV resistance and low abrasion resistance.

One-part polyurethanes offer easy application, cleanup and better properties than alkyds. They are also more expensive and some may be incompatible with amine cure epoxy systems such as WEST SYSTEM epoxy, although 207 Hardener may offer better compatibility. Test first.

Epoxy paints are available in one-part and two-part versions. Two-part epoxies offer many characteristics similar to the higher performance polyurethanes. They are durable and chemical resistant, but offer limited UV protection compared to the linear polyurethanes.

Two-part linear polyurethane (LP) paints offer the most durable protection available. LP's are available as pigmented or clear coatings and offer excellent UV protection, gloss retention, abrasion resistance, plus compatibility with epoxy. However, compared to other types of coatings, they are expensive, require more skill to apply and present a greater health hazard, especially when sprayed.

Bottom paints are available in a variety of formulations. Most bottom paint systems are compatible with epoxy and can be applied directly over a prepared epoxy barrier coat. If you are unsure of compatibility or have curing or adhesion problems with a specific bottom paint, use only a primer recommended for that bottom paint over the barrier coat. Follow the recommendations given for preparation of fiberglass surfaces. Other paints, including marine LP's and primers, are not recommended for use below the waterline.

Primers are usually not needed to help a paint film bond to epoxy, although interfacing primers may be required with some specialized bottom paints and high-build primers are useful for hiding scratches or flaws in the substrate. If the instructions on your paint or varnish recommend a specially primed surface, follow the recommendations given for fiberglass preparation. Self-etching primers do not work well on an epoxy coating because of epoxy's chemical resistance.

Polyester gelcoat is a pigmented version of the resin used to build fiberglass boats and other products. Gelcoat is sprayed into a mold before the glass fabric and resin are applied to provide a smooth pre-finished surface when the part is removed from the mold. It is not often used as a post-production finish coating, but it can be applied over epoxy and is useful in some repair situations. Refer to 002-550 Fiberglass Boat Repair and Maintenance, published by Gougeon Brothers, for detailed information on patching gelcoat over an epoxy repair.

Follow all instructions from the coating systems manufacturer. It is a good idea to make a test panel to evaluate the degree of surface preparation required, and the compatibility and handling characteristics of the finish system.

For detailed instruction on the application of these techniques in repair and construction, refer to specific WEST SYSTEM instructional publications and videos. For complete descriptions of all WEST SYSTEM products, including selection and coverage guides, go to the Product Guide.

UNQUOTE


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## JFC (7 Mar 2006)

If its going to be outside the normal BS1088 Marine ply isnt really a good marine ply to use . Anchor Marine ply is the boat builders favorite but is over double the price of the normal BS1088 used for houses and general building . I think silvermans sell the Anchor stuff . As for the finish and this wont help with your non gloss finish but if you do a 50/50 mix of turps and varnish for the first coat and then 75/25 mix for the rest of the coats you build up a good finish for sun and salt water . The amount of coats is up to you but its good to aim for 15 mixed coats .


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## DomValente (7 Mar 2006)

Thank you all for your comprehensive replies, looks like I have a job and a half for no pay, still summers coming and the Thames can be a pleasant place to laze on a boat, or else.

Thank You
Dom


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