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tfrei

advice on stock for sprit

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I have to craft a new sprit for my CS 17.  I know fir is recommended.  I have sourced some at a local salvage/specialty yard.  They have a lot of quarter sawn fir salvaged from some old bleachers.  They have 3/4 inch thick and 1 inch thick slabs in multiple lengths --some over 10 ft. 

 

I know the plans call  for 1 1/2 inch stock, so I thought I might rip two 1 1/2 inch strips of the 3/4 inch thick (or possibly the 1 inch thick stock) and epoxy them together to get something that will be 1 1/2 inch by 1 1/2 inch in dimension.  

 

From a structural point of view, would this approach work?  Would the resulting spar be strong enough? 

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Lowe's/Depot sell a decking stock that's pretty nice Douglas fir. It's also sold grooved on one side as wainscoting. This stuff comes as 3/4", by 5.5" and has a tongue and groove edge. Sort through a stack and you'll find perfect quarter sawn stuff, defect free. This will be cheaper than a local mill or reclaim yard.

 

The two up 3/4" laminate will work fine, though I made mine from a 3 up 1/2" laminate, with a spruce core (center piece). I saved a couple of pounds, so hardly worth the effort alone. Place the seam vertically along its length.

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Thank you all for your suggestions.  I'll look into the fir sold at Home Depot or Lowes.  I think before I was looking for stock that was at least 1.5 inches thick and didn't see much.  Now, the possibility of laminating opens up more options.  

 

I suppose scarfing short pieces into longer pieces is also kosher? As long as the scarf joints don't line up with each other?

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I suppose scarfing short pieces into longer pieces is also kosher? As long as the scarf joints don't line up with each other?

Scarfs are fine, at least 8:1.  Lining them up won't hurt strength, but I think it looks better staggered.  Making the seam vertical as Paul suggests would definitely be important for booms, not sure it matter for sprits as they are under compression and very little deflection as they sheet at the end and use no vang.

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The sprits aren't very long so you should be able to laminate a couple of full length pieces, but if you have to scarf, go for it - The good news is that sprits are easy to replace.  They aren't permanently attached to the boat.  If your scarfed sprits fail they can be rebuilt pretty quickly.  The original main sprit-boom for Southbound went overboard when I was reefing in a sudden blow one day and I made the replacement the following weekend.  The second one was much quicker to shape than the first.  The original sprit had absolutely beautiful, straight-grained wood at better than 30 rings per inch, but although the replacement was not as pretty, it was strong enough for everything I ever threw at it.  Alan's probably replaced it with a birds-mouth or carbon fiber sprit by now :)

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My local lumber yard sells long pieces (up to 14') of 3.5X3/4 fir decking.  I ripped and laminated a couple of 12 footers to make my sprits.  Albeit, about 4" too short.  Best bet would have been to bend the sails to the spar, then measure the length of the sprit, then cut to length.  New sprits coming sometime soon.  

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I epoxied them and then varnished.  Mine are Douglas fir, and they look very nice finished that way.  I also put a 6 inch color band on each, blue for mizzen, white for main.  They match color bands on the masts.  Otherwise I figured I'd always be holding them up to see which was longer....  And that way I can also tell the masts apart quickly.  Maybe that's just me.  But it looks kind of neat.  I think some builders have put a leather collar where the boom might hit the mast, but I figured I'd wait a season and see if chafe is a problem, and also see where it would actually need to go. Launch date is coming in May -- I hope!

Varnish over epoxy worked well on fir spars I built for previous boat.

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I went with douglas fir too ---taking the idea of using douglas fir flooring from Home Depot and laminating together.  Worked well.  

 

Your idea of epoxy + varnish makes sense to me too. Like the idea of a color band too.  Thanks!

 

 

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The color band's a great idea.  On my boat, though, the mizzen is shorter.  I just use the short stick at the back of the boat.  I had some sitka spruce left over from another boat.  If I didn't have that, I'd be picking through the 2x6 (non-sitka) spruce pile at Lowe's.  Poplar is cheap around here, and light, too.  It's a great choice, too.  Hirlonde is correct-- the loads aren't as demanding as a boom.  (Your sheet should attach to the sail, not the sprit.)  Epoxy+varnish or just varnish, plus a chafing leather.  I've seen wraps of twine used instead of leather, too.

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I also used Douglas Fir for my sprits, and I varnished them.  I never epoxy solid wood before varnish.  I went so far as epoxying my decks and not the rubrails.   I see no advantage and some disadvantages, especially as they get older and need refinishing.  It adds nothing to the life of the varnish and the varnish is the UV protection, so why bother?  It is different with plywood as there are other issues regarding integrity.

 

Don- you consider Poplar light?  I added chafing gear my second year, was a great idea.  I picked up a piece of silver gray textured leather (suede like) for $25 at a remnant shop and have since gone crazy making chafe gear for my oars, spar crutches for trailering, my oar and paddle brackets and even my tiller handle.  Because I can  ;-)

 

Paul- I like color coding stuff.  Alan color coded all my lines for me when I ordered them all from B&B.  Halyards are yellow trace, snotters black trace, tack downhauls red, etc.  Though I did not label my sprits for the same reason Don didn't (length).

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I agree with Dave on the use of epoxy under varnished surfaces. Unless there's a real need for epoxy, such as a sheathing, it just complicates maintenance chores.

   Species choices can abound and Douglas fir is a good one, but an argument could be made for aluminum too. How much mast tube material do you have left over?

   Rather than color coding stuff, I make application specific attachments, such as unique mast heal tenons, that can only fit their steps. Now I do add color bands at mastheads, but more for styling than anything else.

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I grabbed a photo of the sprit ends last night.  I realize the sprit and mast pairs are different lengths, but on my 17, both masts will drop into tubes, so there is no difference in the heels.  As long as I was painting them anyway -- toward PAR's point of styling -- I figured they might as well be different colors, and there will be one less point of confusion during rigging.  And like Hirilonde says, lines will be color coded as well.  Temps here (Wisconsin) are inching toward 60s.  Can't wait to get the final work done.

 

As far as varnish and epoxy, belt and suspenders?  I've never had an issue, maybe because the sun is not as much a factor here.  I feel like the epoxy provides a very solid base for the varnish.  Each to his own.

sprits.jpg

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Quote

but an argument could be made for aluminum too.

I made aluminium sprits because I happened to have 2 pieces left over from a previous build. Light, strong and able to run reefing lines internally but noisy as anything where they touch the mast. Still planning on some sort of chafing system to reduce the noise but haven't got round to it yet.

Cheers

Peter HK

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Poplar can come light or heavy.  If I can get some light 12 footers, I'll probably build a Wee Lassie out of it.  The light version is down there with spruce and cedar.  Haven't used it for spars, yet, but Chick has.  

 

I prefer a coat or two of epoxy on porous or grainy woods such as mahogany, oak, or walnut.  It is an excellent surface evener, eliminating the need for about 5 coats of "filler varnish".  My sitka really didn't need epoxy, and I don't remember now whether I did or didn't seal it.

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I too, laminated the sprits from two pieces of fir decking material.  As I made the originals too short, I now have 3 sprits (the original mizzen sprit to soon become an oar, as the original main is now the mizzen sprit).  Different colors on the ends of the sprits is a brilliant idea.  

 

The only wood I would treat with epoxy would be Okoume, the Doug Fir will be happy without it and your life will be simpler.  

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