Tuesday, May 5, 2015

New Spreaders For The Mizzen

[Sorry about the re-post of this one. I just opened it to look at something, and Blogger turned it back into a draft. ??!?]

This post originally appeared on Windborne in Puget Sound

Rot.
It's funny, isn't it - how something like this can prey on your mind - kind of subconsciously, but still gnawing away just below the surface.  Just like the rot - slow  but relentless.

Yes, I've known about the rot in our mizzen spreaders for a while now.  And I have been intending to deal with it for all that time, but the "right" time hadn't occurred - until now.

So I tied off the mizzen halyard to act as an auxiliary cap shroud and climbed the mast with my tools.  Removal of the spreader was far easier than my worries had been leading me to anticipate, even tho it had been up there for 37 years, untouched and uncomplaining.

More rot at the root.
I had decided that the replacement spar would be made from  pressure treated lumber (like the second-generation bowsprit) so that rot would never again be an issue.  Now if you have ever hoisted up pressure treated lumber at the lumber yard, you know that it is heavy.  And heavy is not good aloft on a sailboat.  But most of that weight is water:
To pressure treat lumber,
  • it is put into a sealed vessel,
  • the vessel is evacuated, removing nearly all the contained water in the wood as well as air trapped in its porosity.
  • Then after a suitable degassing period, the water-based treatment solution is admitted to the vessel, and it is pressurized, forcing the solution deep (well kind of - see below) into the wood.
That's why the wood is so saturated with water when you buy it.   But if you simply let it stand in a reasonably dry place for long enough, it will return to a more "normal" moisture content - and much lighter weight.  In fact, the replacement spreader is actually lighter than the old one (which of course does have a lot of water in it due to the rot).

Well it only took a couple of hours with a skill saw, power plane, belt sander, and a router to duplicate the shape of the old spreader:

 

If you've ever cut into a pressure treated board, you know that despite the violence of the treatment process, the treatment does not reach the core of the board.  And since the spreader tapers from 1-1/2" thick at the root to 1" at the tip, and from 5" to 1" side to side, a lot of wood was removed from the surface and from one side.  Tapering the thickness and cutting away the sides revealed wood that was only lightly treated.  What to do?

People who handle pressure treated lumber day in and day out (building decks, for instance) have always had to deal with the cut ends of boards, where the untreated core gets exposed.  Long ago they found the answer:

Want to rot-proof some wood?  This is just the ticket
 
This stuff, which you can find now that you know its name, is just the ticket.  You just paint it on and wait for the solvent to evaporate.  Wear rubber gloves - its not nice stuff.

Add a coat of epoxy to permanently seal the surface.
Bed the hardware in polysulphide.

A couple coats of paint, and et voilĂ !
And now, even tho I still have one more spreader to go, it feels like an invisible weight has been lifted from me. The subconscious mental anxiety that was silently eating away at my contentment, my satisfaction, my peace, is now gone, just like the rot.

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