Coating timber masts

  • 24 Jun 2018 05:22
    Reply # 6337484 on 6337337
    Anonymous wrote:
    Anonymous wrote:


    You have now done many miles in Footprints, David, and the proof of the pudding is in the eating.  A salient point could be that you use webbing for the parrels: correct me if I'm wrong.

    H

    Certainly there has been no wear on the starboard side of the mast as a result of the batten parrels. Any wear is on the port side and is a result of rubbing from the battens, despite the foam cushioning on the batten pockets. We were on the port tack the whole way to, and back from New Cal, so there were a lot of sea miles on the port tack.
  • 24 Jun 2018 00:57
    Reply # 6337337 on 6333662
    Anonymous wrote:

    There is also the option not to cover a timber mast in Fiberglass. The mast on 'Footprints' is painted only,and is now 20 years old, and is in good condition. Yes there are some bare patches of timber from time to time before I get around to re-coating them, but any moisture in the timber dries out. A couple of years ago I did have a conversation with a very experienced professional wooden boat builder friend of mine and his view was that by sheathing a mast in fiberglass the risk of rot is significantly increased in the event that moisture is able to get in behind the sheathing, such as through a chafe area.

    You have now done many miles in Footprints, David, and the proof of the pudding is in the eating.  A salient point could be that you use webbing for the parrels: correct me if I'm wrong.

    However, I have seen several junks that have had real problems arising from unsheathed wooden masts, where the parrels have been sawing into the soft wood and then invariably ending up in the same groove and making matters worse.  This is why Jester had those strange-looking wooden strips up and down the mast.  Both Passepatu and Pacific Spray have this sort of damage to their masts - with the latter the damage is as yet very superficial, because the masts haven't done many miles.  I think it's the difference between a weekend sailer and on ocean voyager - the latter will frequently sail in one year what the former does in ten.  We sheathed the masts on Badger, and as far as I know they are still in fine shape, but even so there was a dent all around caused by the 6mm boom parrel.  It would be interesting to hear from Tony and Sally about how the masts have stood up on Ron Glas.

    My own opinion of moisture getting behind the sheathing, is that the same applies to a plywood hull.  Or to crevices in a steel boat.  If the job is done properly to begin with, the matter shouldn't arise.  John Guzzwell was told the same, but sheathed Trekka's mast in polyester and glass, and did the same to Tsu Hang's new masts.  Being JG, one can rest assured that the job was done properly and apparently the masts survived for decades.


  • 22 Jun 2018 22:17
    Reply # 6333662 on 6331372

    There is also the option not to cover a timber mast in Fiberglass. The mast on 'Footprints' is painted only,and is now 20 years old, and is in good condition. Yes there are some bare patches of timber from time to time before I get around to re-coating them, but any moisture in the timber dries out. A couple of years ago I did have a conversation with a very experienced professional wooden boat builder friend of mine and his view was that by sheathing a mast in fiberglass the risk of rot is significantly increased in the event that moisture is able to get in behind the sheathing, such as through a chafe area.

    If a varnish-like, or natural finish is desired on a timber mast I would use one of the new exterior acrylic oil coatings. I have been using what is described as an outdoor furniture acrylic oil on my outside furniture, and the side of my hot tub, for the past couple of years. It dries hard with a an opaque finish which highlights the timber underneath. And it is very easy to re coat from time to time. I have not yet figured out how 'acrylic' and 'oil' go together in the same product, but it works very well.

    Last modified: 22 Jun 2018 22:26 | Anonymous member
  • 22 Jun 2018 11:19
    Reply # 6332178 on 6331372
    Anonymous member (Administrator)

    I have had two wooden masts, glassed in epoxy and then coated with 2-pot varnish or paint.

    The first on Malena had 9(!) coats of clear varnish, called SP-1000 (?), supplied by West Systems. It lasted for about 14-15 years with no maintenance. One could then see that the mast was turning grey on the sunny side of it. Unfortunately, the new owners did nothing about it, so as the coating cracked, moist entered and developed a perfect greenhouse for rot.  That mast was chopped up for firewood in 2014.

    On Johanna’s mast, 2-pot paint was used insted of clear varnish(2001?), and that seems to hold well.

    On the two last hybrid masts, I have painted the spruce top sections with 2-pot paint with no glass underneath (except at the joint). That polyurethane appears to be seriously strong and it also sticks like glue to any surface, so I have good hope for it.

    Thinking back on Malena’s mast, I have a nagging feeling that the varnish itself did not fall apart. It just let through enough UV-radiation to kill the epoxy under it. I may be wrong, though.

    What I would like to do, is to make a test by glassing a piece of plywood. Instead of using epoxy for resin, I will use 2-pot varnish. In case the varnish penetrates and fills the glass properly, this could be a very durable and strong alternative to the epoxy.

    Arne


    Last modified: 22 Jun 2018 11:20 | Anonymous member (Administrator)
  • 22 Jun 2018 08:42
    Reply # 6332068 on 6331372

    I have had good success with wooden masts, by coating them with one layer of woven rovings ('boat cloth') and epoxy, then filling in the weave with epoxy slightly thickened with colloidal silica.  Sand the mast and then apply as many coats of two-part polyurethane paint as is necessary to build to a solid colour - usually four.

    I've have also finished three masts clear, coated with cloth and epoxy (without the silica - you need an extra coat) and using International Crystal to varnish them.  An absolute minimum of six coats should be applied.

    International Perfection paint spreads beautifully; indeed most polyurethanes can be satisfactorily hand painted onto a mast.  I often finish with clear two-part polyurethane that is guaranteed to have UV inhibitors - the gloss seems to last longer than paint, although this might simply be my impression. 

    Varnished spars look lovely and yes, the varnish will discolour if water gets underneath.  However, if you've done your job properly, water won't get underneath.  Chafe will attack the best of paints, and, as you've discovered, glass and epoxy, too.  If I were you, I'd be concentrating on eliminating the chafe.  If there's no chafe and plenty of coatings, you should get away with repainting/revarnishing the mast only every 5 years or so, although I'd always repair any damage, myself, as soon as it becomes apparent.

    I'm using Carboline products (can't afford Perfection and the range of colours is too limited): I used this for the aqua paint on Fantail and it still appears to be holding up on the topmast, although I haven't seen the boat for six months.  I made the mast 8 years ago.


    Last modified: 22 Jun 2018 08:47 | Anonymous member
  • 22 Jun 2018 00:27
    Reply # 6331618 on 6331372

    Hi Graham,

    we are now at our house under construction on Russell Island. I would would really like to meet you at some time and if you are intending to be in Moreton Bay that would be a great opportunity. The anchorage opposite the ferry terminal on Russell seems to be sheltered and you can tie the dinghy on the non ferry side of the terminal for getting ashore.  Our house is habitable so you could stay over if you wanted.  Gary knows our house well as he has helped in the build and Dieter has his catamaran at Victoria Point so could join us for a get together. I hope that sounds like a good idea for everyone. 

    All the best, David.

  • 22 Jun 2018 00:15
    Reply # 6331519 on 6331372

    I agree that a clear finish will show up water ingress long before it becomes a serious rot problem.  The price you pay is that the UV resistance is poorer than painted finishes, even with UV resistant epoxy.  I have been told, but have no direct experience, that putting a UV resistant varnish over the epoxy helps.  The varnish will begin to break down first and can just be sanded and recoated.  As for the chafed patches, can you patch them, or do you need to strip the mast back to bare wood?  The advantage of using epoxy is that it adheres well and is much more successfully patched than polyester resin.  I am assuming you used epoxy?

    I am still in Mooloolaba.  I had intended to come to Moreton Bay earlier but was too ill.  Then I recovered around Easter and decided to head north.  But, after slipping in early May, I had a major engine problem.  The engine is just back in now and I am waiting to fit water temperature and oil pressure alarms.  I've now decided that it is too cold to head north, which involves some night sailing on this slow boat.  So I am hoping to come down to Moreton Bay after all for a while, then start heading north later when it warms up.  I might spend the summer around the Keppel Islands before continuing back to FNQ next April.  So, if I can stand the cold at anchor, (I intend initially to go to Scarborough Marina) I hope to make it down to Southport and perhaps we can catch up?  Of course, I can always go into one of the Gold Coast marinas and plug in my fan heater if I am too cold!

    Last modified: 22 Jun 2018 00:17 | Anonymous member
  • 21 Jun 2018 23:19
    Message # 6331372

    I’m going to be pulling my mast out later this year to recoat it. I used a clear two pack originally and this has now weathered. I may also need to replace the fibreglass layer as this has worn in places. So two questions.

    1 Do I go clear again or paint it? Personally I’d be happy to paint it though it does look good clear finished. I know there is the view that a clear finish means signs of rot are visible.

    2 What ever I use will have to be hard wearing with high uv resistance, so anyone have any brand recommendations?

    Last modified: 21 Jun 2018 23:22 | Anonymous member
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