Found D. Fir Mast Material

[Maria CS20 104]

After draggin my feet and squirelling my way around lumber yards I found 7 1"x12" x 14' fir lumberm all very clear, saw no pitch pockets. Couple of the board have some damage to one edge probably from movement during storage over the years but I should have enough to do both masts at 22' and still have 40% left over for use on a 12 foot spindrift (future project boat for grandsons). The cost was about $2.30 a board foot, last of stock deal and a friend owns the yard where we found the wood. He had looked about 8 months ago but recently found a stash while moving stock around and I happened to contact him today and he had the material on his some available list. He delivers tomorrow and I will go down later this week to hand pick the remaining lot. We have been very lucky to find some amazing lumber at private yards by digging around in all the back dusty corners.

Lots of cutting and scarffing ahead, jigs all made and ready. I'll cut some practice strips and set up a two foot sample with my bride to get the hand of it. Do need to set up some finger boards and extensions on the router table to simplify the work.

I keep reading that I should not use epoxy but some phynallic (?sp) glue like gorilla whats the general consensus on gluing staves?

I figure staves to be 1.2 inches wide with a thickness of .6 inches (maybe .7 inches).

Been reading a lot and inspecting sites and work in lots of places and it looks pretty straight forward, hpoe so. One of these days soon, we'll post a host of pictures.

Jim

[Ray Frechette Jr]

For the life of me I can not understand the appeal f Gorilla Glue. The question keeps popping up all the time.

It is expensive. Cost per ounce clearly far more expensive than epoxy. If there is a gap in the glue line it is far weaker than epoxy. And it is not as waterproof as epoxy.

To me Epoxy has all the advantages.

[Howard]

Score!!!

When I did the birdsmouth mast for the Spindrift, I was allowed to pick through a pile of 2" x 12" doug fir lumber (private yard where I bought the lumber to build my house) and found about three sticks that while not completely clear, had good clear sides on them. One was flat sawn and almost entirely clear and while it didn't have the tightest rings on it, was far and away the most solid and dense. It turned out to be the pick of the litter.

I looked at the potential gaps in the joints and went with thickened epoxy for mine, with also included the fine walnut shell to prevent squeeze out. It has held up well and was not that much of a problem to plane down.

[Ray Frechette Jr]

If you have 1x 12 board s why on earth would you opt for Birdsmouth instead of a simpler box construction with internal gussets? Much simpler and cleaner and neater to set up and less hassle than Birdsmouth. I would only opt for Birdsmouth if I had a lot of long skinny pieces given to me free.

[Maria CS20 104]

Hey Ray, I missed the opportunity to see you when I was living in Madwaska to get the best of the best tips from a true master builder. I understand the issues associated with your location and all. First I am going with the epoxy, I seem to recall a previous post on your part and others that it is the best long term approach and your experiance has shown that year after year it is NOT an issue.

I guess I am going with the birdsmouth because I have already drilled all the appropriate holes with reenforcement collars, footings and completed and installed the fiberglass tube forward. Additionally, I have no idea what internal or even external gussets are or would be and I kind of like the roundy mast traditional look as seen in the plans. I have only seen one box mast made and participated in it's sanding and varnishing better than 40 years ago. I did seriously think about box masts at the beginning of the project whe I had less experiance manipulating wood and equipment, but I like the long roundy masts.

I do believe that there is substantially more waste with birds mouth masts but the challenge intrigues me now that I've built so many of the parts and pieces on this beast. I think after I made the oars from a 3 1/4" x 1 1/2" x 16' chunk of my 2"x12" 16' chunk of wood, adding some 3/4" spacers to widen the blade to about 5 3/4" finished, my confidence is higher and I like the idea and feeling of completing a more difficult project and the feel of the wood in my hands as I work it and watch it change into something few others have made. I want the experiance as well since I plan to make birdsmouth legs of walnut for my sons' dinning table set.

I did SCORE on the douglas fir and I expect I'll get a better price on the short stuff he has left, about 300 to 400 board foot left as I recall by calibrated eyeball on the last of the stack, most around 8 to 10 feet in length, some 6" wide much 8" or so, all clean by sight, no knots but robably some pitch pockets. He's had this stuff for 15 or more years under cover and properly stacked and weighted to avoid cupping or twisting, I would say it's cabinet grade or better for the most part. I am thinking of remaking hatchcovers with this stuff just for fun and looks.

I would like the info on box masts and whatever internal gussets are for future reference, heck if I screw these up I can always modify my approach. I am making one at a time.

Best to all and thanks for the input Ray and Howard,

Blessings

(we just became grandparents to a 6lb 9 oz little girl, our 3rd grandbaby, keep them all in your prayers and thanks)

Jim

[Hirilonde]

Box spar with gussets looks like this in cross section:

Very simple and very strong.

[Ray Frechette Jr]

Box masts with internal gussets can be completely round after shaping and need not be square with rounded corners.

The advantage is all in the layup.

Basically each side is as long as the diameter of the mast will be. You then glue and tack in small trianular gussets on one side of each side offset in the thickness of the wood being used. The triangular gussets are of the correct dimension so looking down the glued up mast the interior will look like a perfect octagon.

You leave out gussets in the areas you want the mast solid. On A CS bot or Bellhaven that would be the top and bottom section and where you have fittings such as the snotter, tabernacle pin area. In these areas you fit in solid squares that completely fill the interior when doing final assembly.

Once gussets are cured you spread epoxy on all interior portions.

The gussets make assembly a Breeze compared to birdsmouth. They align everything very nicely. Having long wide boards to assemble there is no sagging or banana masts ever as it is all self supporting horizontally and a whole lot less messy.

Once box section is cured you 8 side the blank and then 16 side it and then round to final round shape. Simple as pie and you have a perfectly round hollow mast.

Now if someone gave me 1 by 2's of Sitka Spruce free for the taking, then I would be interested in using them for Birdsmouth . because they are too small to be practical for much else...

[Ray Frechette Jr]

Truth be told I am far more fond of aluminum tubing section masts than all wood masts. Engineered material with known bend characteristics and strength and lighter in weight.

[Hirilonde]

Box masts with internal gussets are completely round after shaping. They are not square.

Not necessarily, Concordia masts have rounded corners only. The term box is used because the construction has 4 sides, it does not necessarily reflect on the final shape.

[Charlie Jones]

built the masts on the Princess 22 as composite- aluminum lower sections, birdsmouth upper. The birds mouth upper section weighed less than the aluminum

Having built over a dozen spars now using the technique, I'm sold on Birds mouth for round spars. Or even those made somewhat rectangular.. The technique is amazing, and extremely versatile. Quick to cut, using a table saw. Last CS 20 I built I cut all staves for both masts in about an hour, tapered in another, then glued. Had both masts in clamps in one afternoon

Also very very simple to glue two halves, then open them up to add internal blocking where needed, and final glue the halves together.

I am in complete agreement with Ray on the Gorilla Glue. Tried it in my furniture shop, had some failures, quit even buying it Epoxy is the way to go.

[Tom Lathrop]

For the life of me I can not understand the appeal f Gorilla Glue. The question keeps popping up all the time.

It is expensive. Cost per ounce clearly far more expensive than epoxy. If there is a gap in the glue line it is far weaker than epoxy. And it is not as waterproof as epoxy.

To me Epoxy has all the advantages.

It is the power of advertising. There is no other explanation since it is inferior to epoxy in everything important to boatbuilders. I like box spars with rebates cut in two of the four side pieces. Automatic allignment is a big advantage in long spindly pieces. Doug fir makes great masts but I do prefer aluminum for the reasons Ray gives.

[Ray Frechette Jr]

built the masts on the Princess 22 as composite- aluminum lower sections, birdsmouth upper. The birds mouth upper section weighed less than the aluminum

Yes but I am willing to bet the upper sections were much smaller diameter than the lower sections would have to be if wood. Not exactly and apples to apples comparison.

Box masts with internal gussets are completely round after shaping. They are not square.

Not necessarily, Concordia masts have rounded corners only. The term box is used because the construction has 4 sides, it does not necessarily reflect on the final shape.

OK, Let me edit it to say Box Masts with internal Gussets can also be completely round and need not be square with rounded corners.

[Maria CS20 104]

I'll try a sample of both the box method and birdsmouth. I am concerned about the banana effect potential as I have to create a truly flat work surface with brackets.

Thanks Again to All

jim

[Hirilonde]

For the life of me I can not understand the appeal f Gorilla Glue. The question keeps popping up all the time.

It is expensive. Cost per ounce clearly far more expensive than epoxy. If there is a gap in the glue line it is far weaker than epoxy. And it is not as waterproof as epoxy.

To me Epoxy has all the advantages.

It is the power of advertising. There is no other explanation since it is inferior to epoxy in everything important to boatbuilders.

It is this same type of advertising that has 3/4 of the boaters thinking they need to bed everything in 5200 regardless of whether removal is part of maintenance.

[Howard]

Looking at Dave's graphic of the box mast, and Ray's description of the gussets (I didn't realize the corners were that large), if my math is correct, to get to that perfect octagon internal shape, a mast as large as 6 1/2 inches could be built using commonly available 1.5" stock for the gussets. That would seem to be a pretty big mast.

By the way, what is the scantling size (stave thickness) for a box mast? I seem to recall stave thickness for a birdsmouth is 20% of overall diameter. Not sure I have ever heard what it is for box masts.

[Ray Frechette Jr]

Wall thickness wants to be the same.

By having gussets form an internal octagon the thickness of the wall section after 8 siding will be same in the thickest part as it is on the thickest part of the flat faces before 8 siding.

If going with a square mast with rounded corners and not rounding it over completely the gussets can be much smaller.

[hokeyhydro]

I'm fond of birdsmouth masts because I have the tooling to do the staves rather swiftly, and I like the way the pieces kind of snap together. I've assembled a 22' mast by myself, using epoxy, and since epoxy doesn't need, and should not have, mega-clamp pressure, I used cable ties AKA zip ties to cinch it all up.

I seem to recall that when using doug fir, because it is stiffer than many woods, one can shave the scantlings down. As in 20% for spruce etc, but 15% for doug fir. Think I read that bit on Duckworks.

[PAR]

On small spars, aluminum if difficult to beat for weight to strength ratio, but once you start to introduce some "issues" and length, aluminum becomes less desirable (up to about 30'), compared to a well thought out birdsmouth. For example, I've just offered a quote for a 32' birdsmouth mast. It was heavier then aluminum with the standard 20% wall and typical dimensions, given the rig type, tapers, loading, etc. I changed the dimensions to accommodate a 15% wall thickness and now have a mast that is 2 pounds lighter then aluminum, sweetly tapered, doesn't make that God awful racket when lines slap it and can be finished bright.

As to general rules of thumb on spar scantlings, well don't try it. Spars really need to be up to the tasks they're expected to tolerate, particularly if free standing. When I changed down to a 15% wall I had to increase the heel and masthead diameters considerably to compensate for the lose of modulus. If you're unfamiliar with this sort of work then you're best sticking with the designers plans.

I like birdsmouth sticks and build quite a few, but I do admit that given a choice, on most boats a composite mast of aluminum and birdsmouth or carbon are attractive alternatives. I don't find the birdsmouth much more difficult then a box section, even my modified box section. All build methods have good and bad things to consider about them. I hate the look of a box section spar, even if you heavily roll the corners. Many of the masts I've built recently have been rotating, which isn't practical with a box section, nor is a luff sock, which I guess is possible, but I've never seen one.

All in all, I think most that are building their own boat, have a bit of pride in the effort they've applied and a nicely tapered, possably brightly finished set of spars, can really make a boring boat a fanciful eye feast.