rectangular wooden mast

Discussion in 'Wooden Boat Building and Restoration' started by fishweed, Dec 7, 2006.

  1. fishweed
    Joined: Jun 2006
    Posts: 45
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: san leon,texas

    fishweed Junior Member

    I am going to build a rectangular wooden mast and the material I will used will be Douglas Fir and epoxy as the glue, I have "Elements of Yacht Design" and I have ordered "Skene's Elements of Yacht Design" I am trying to figure out at what position the spreaders are located on the mast,I have a drawing of the boat, and I will scale the position from the drawing, my question is, is epoxy the best choice for the glue?, and the spreader arms I will make out of stainless or aluminum, I will fabricate a cap for the mast out of stainless for the rollers and the stays, and I plan to put blocks inside where the spreaders, winches mount to the mast, am I missing anything?, the boat is a 36 ft roughwater motorsailer, the jib is a roller and the main is a roller without the boom., So my questions are: what is the best glue, and speader material, and should I paint the mast with epoxy when done?
     
  2. Scott Carter
    Joined: Oct 2006
    Posts: 130
    Likes: 11, Points: 0, Legacy Rep: 143
    Location: Annapolis

    Scott Carter Senior Member

    Fish -
    I've recently posted a similar thread re. gluing up an octagonal birdsmouth mast. The past few posts have dealt with this very same [glue] issue. You can read for yourself, but according to some who know, epoxy (as well as other glues) has limitations on the size of the individual glued pieces that it can hold together. This relates to "the larger the individual piece of wood the greater expansion/contraction its glue joints will need to resist", or something like that. My initial choice was (and still is until I hear back from the West System) West System with various fillers. I hope they'll set me straight with their recommendations. If they, too, steer me away from epoxy as a glue for this stick (the staves on mine are 3"x8"x85') then I haven't a backup plan. I'll be keeping an eye on this post to see what I can glean from it. So, to the rest of you out there, especially you glue-rues, let's help this guy out a little, huh?
     
  3. lacasmarine
    Joined: Dec 2006
    Posts: 32
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: gainesville , ga

    lacasmarine Junior Member

    I've used west system for a mast repair with micro-fibers as my filler.
    that same mast came back 3 years later. still holding strong(it came back do to short bridge says owner.)
    coated with epoxy then 95 schooner varnish.
    hope that this helps
     
  4. Gypsie
    Joined: Apr 2005
    Posts: 123
    Likes: 3, Points: 0, Legacy Rep: 50
    Location: Lombok Indonesia

    Gypsie Randall Future by Design

    Resorcinol glue has done the job for many years, just make sure that all your joins are air tight. Remembering the days when all joinery had to be air tight before the "gap filling" epoxy glues turned good joinery carpenters into brick layers.
     
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 488, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Resorcinol and plastic resin have been the glue of choice for some time. Wood butcher's friend (epoxy) is a relatively new comer to the industry. Used within it's limitations, epoxy is a wonderful adhesive. Typically, resorcinol was used on painted masts and resin on bright sticks, mostly because of the glue line color.

    Scott, can you email me (click on my name) your sail plan dimensions? Your 3" x 8" stave dimensions seem big to me. I happened to be looking at some large mast specs, for some old AC defender yachts the other day and two Herreshoff boats (both winners) had masts as big or bigger with considerably less wall thickness. Granted these were limited use racers, but one was 60% thinner.

    With your sail plan specs, I can rough up some dimensions to see how close they come, if you're interested.
     

  6. BOATMIK
    Joined: Nov 2004
    Posts: 298
    Likes: 15, Points: 28, Legacy Rep: 190
    Location: Adelaide, South Australia

    BOATMIK Deeply flawed human being

    I've had really good results coating existing timber masts with epoxy.

    With just varnish the wood seems to move quite a bit but when they are given three coats of epoxy (no thinners to ruin the properties of the epoxy) the surface is much more stable and we've been getting much longer periods before the surface breaks down.

    The masts are varnished as well to protect the 'pox from UV breakdown.

    I've been tracking one of the jobs that was done 5 years ago that had some minor cracking along the grain that was causing problems with cracking the varnish and then letting water in, then the water entering and leaving making the timber move so the varnish breaks down faster. We varnished it a couple of times to try and fix the problem, but ended up stripping completely and sealing all points with epoxy.

    35ft keelboat kept at a marina. I've been back a few times to give it coats of varnish to keep the epoxy protected and the cracking hasn't reappeared.

    So epoxy in this case has done the job of preventing the timber from moving round with moisture absorbtion.

    I have built some hollow timber masts new as well - and used epoxy to hopefully prevent movement and stressing the glue joins. So far so good, and considering it has done such a good job on the older spar I expect it to do fine on the newer ones anyhow.

    Not WEST but another premium quality boatbuilding epoxy.

    MIK
     
Loading...
Similar Threads
  1. Chris06
    Replies:
    2
    Views:
    317
  2. Rod Tait
    Replies:
    2
    Views:
    414
  3. Masjaf
    Replies:
    6
    Views:
    786
  4. Jeff Vanderveen
    Replies:
    18
    Views:
    1,593
  5. Rod Tait
    Replies:
    3
    Views:
    937
  6. Rodrigo Hurtarte
    Replies:
    15
    Views:
    1,905
  7. Rod Tait
    Replies:
    2
    Views:
    1,064
  8. stewart thompson
    Replies:
    17
    Views:
    2,700
  9. Rod Tait
    Replies:
    0
    Views:
    1,438
  10. Rod Tait
    Replies:
    0
    Views:
    1,264
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.