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Date Posted: - Tuesday - 08/19/08 - 2:05pm
Author: Steve Burge hull #55
Subject: Mast maintenance

Hello,
My spruce masts need help. They have not been treated in over 6 years, most of the varnish is gone and although the spruce seems solid, I need to either sand and re-varnish or sand and coat them with white epoxy as some of you have done. My question is: If I decide to epoxy them, how much sanding is necessary. would it be the same amount of sanding as if I were to restore to the original finish or can I settle for a clean,smooth surface, then apply the epoxy coating? OR....should I scrap the wood altoether and go with aluminum. I hate to throw the wood away as the booms are in great shape and I love the wood look.

Any advice would be appreciated.
Steve

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Replies:

[> Sitka Spruce -- Gitano (M31 #95), - Tuesday - 08/19/08 - 2:42pm

Steve,
I just made new masts, although I was going to scarf the old one back together (I found a decent source for the spruce). One thing to check is the old resorsinol glue seams. If they have been exposed, check that they are all still sound. I used Interlux wood sealer (3 coats) and clear penetrating epoxy sealer only at the mast step, mast head and spreader bolt penetrations. No need to penetrate the rest. I went with Bristol (traditional amber) two part polyurethane varnish over the wood sealer. The Briston has 10 times the uv protection and is 100 times stronger than traditional varnish, and you can lay 3-4 coats a day. Its tacks up dry to the touch within an hour. Its also just as beutiful as traditional varnish, but lasts much longer. Email me if you want photos.


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[> Varnish vs paint -- Steve M-32 #59, - Tuesday - 08/19/08 - 2:59pm

One of the things I have read with regards to wooden masts is that varnish lets you see whether water has gotten under the varnish so you can fix it before it starts to rot. When I bought my boat the masts were painted and looked to be in great shape. After I stripped them I found myself making more than a few dutchmen to fix some problem areas. I won't go back to an opaque coating for my masts after that experience. I have stuck with traditional spar varnish rather than going to a poly. As Gitano says poly is harder but harder is not necessarily advantageous on a mast. A more flexible varnish withstands minor hits better and works with the wood as it expands, contracts and flexes over time. I don't want to sound dogmatic on this as there are definitely different opinions on the subject and each type of varnish has its' good and bad points. BTW on the subject of surface prep, don't listen to the people who talk about going down to 400 grit or more and trying to get a perfect finish for varnish. Go to 120 use a first coat split 50/50 with thinner and then go for the most thick coats you can. I want protection for the mast I'm not worried about perfection


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[> Spar finishes -- Craig M31-25 Hibou, - Tuesday - 08/19/08 - 3:10pm

Last spring we refinished our spars, they had peeled and turned gray over the winter. We stripped the remaining varnish off, gave the wood a good sanding, a bleach wash, and then applied Cetol. They look good as new, now.


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[> [> Flexible Finish -- Gitano, - Tuesday - 08/19/08 - 3:42pm

We have actually done some test samples at NorthBay Boat Works (www.northbayboatworks.com) where we finished up a spar and applied bending. The two part polyurathane actually does stretch, just about as well as traditional cured varnish. Its a matter of preferance as to maintenance. i.e. having to sand between every coat, and wait until the following day to apply another (and doing that twice a year), or being able to "wet coat" several layors on a single day, and have it last a couple of years beore having to apply another. We found that the key was using the wood sealer as opposed to thinned Bristol (with acetone)as the sealer coat. The one drawback is that patches are more difficult to apply with polyurathane than with varnish. Have to sand and feather down before appying more coats.


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[> [> [> flex -- Steve M-32 #59, - Tuesday - 08/19/08 - 4:12pm

Interesting. I must confess I hadn't tested the finish I just went from my boatbuilding instructor who has a lot of years in the business. Oh well, learn something new every day :-)

On the matter of refinishing I have have found that once a year is fine though that probably has something to do with the fact that there is no sunshine for six months out of the year up here :-)


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[> [> [> [> Wooden Boats -- Gitano, - Tuesday - 08/19/08 - 4:34pm

Indeed! I find most wooden boatbuilders stick with traditional means as opposed to using modern products. That is the case here in Sausalito as well, and is indeed the case of the instructors at the Arques School of wooden boatbuilding (http://www.arqueschl.org/)from which the owners of NBBW are all graduates. Thats why we did the tests. All wooden spars still require routine maintenance, and inspection, regardless of the finish. I actually painted the mast tops from the point of my reach while standing on the spreaders. the mast below that point are varnished with Bristol. One note: I highly recommend replacing the spreader tangs with a different design. See my post about dismasting
http://www.voy.com/119861/2391.html


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[> Or Paint -- Randall, Murre, M31, - Wednesday - 08/20/08 - 12:31am

To your specific questions:

-Don’t know how much sanding you were anticipating, but regardless of the finish you choose, I think you’ll need to sand down to clean, yellow wood. You will likely have some remaining dark spots; as long as they are surface, I’m not sure it’s worth grinding them out. I’ve not gone below 120 or 220 grit (which ever is at hand) and have not had a problem with adhesion or finish “perfection”.
-As to aluminum masts, one thing to consider is that you don’t need necessarily to replace both masts. I’ve seen a couple mariners with an aluminum main and the old spruce mizzen. I think aluminum could stiffen the boat considerably by reducing weight aloft, but could be an expensive and relatively technical transition whereas recoating what you have is tedious but easy.


A note on my experience (not by way of a recommendation, but to add color to the above posts):

-When I acquired Murre, her spars were painted white. Two years ago I removed all the hardware from the main and took it down to bare wood so as to assess its condition. I found the finish was paint over varnish and, beside a few surface dark spots, the exterior was sound. I sealed the mast with three coats of Smiths and topped that with three coats of single part “urethane”. When reinstalling the hardware I was especially focused on generously gooping all hardware fasteners and feel confident the seals are sound. Two years later (this last winter) I had the masts out for the bulkhead job and found the paint was marked and dirty from halyard wear, had flattened a bit, but was otherwise unchecked—could likely have gone another year or two without maintenance. I sanded off the dirt and the flat and applied another coat.

Which is to say, I think varnish superior to paint for the reasons listed above (it allows you to see trouble spots otherwise painted over—and, hell, it looks great if kept up), but it’s not the only good option, and if time and money are an issue, paint works.

Given my druthers, I would varnish. I too have heard lots of good about Bristol; I’d check it out. I use Cetol Light extensively on Murre’s exterior wood and have grown to like its rich, redish tint—I’ve even Cetoled over the bow sprit’s traditional varnish finish, which makes the spruce look, from a distance, more like fir. Though Cetol is dead simple to use and long lasting (finish once a year in full sun climates), it’s an acquired taste.


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[> [> Paint over Varnish -- Gitano, - Wednesday - 08/20/08 - 1:52pm

I highly recommend that if you are considering painting the mast, that you varnish it first. That way the paint does not get into the grain, and if you ever want to convert it back to varnish, its easy to strip off the outer layer.


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