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I'd like to get started on my mast and I reviewed previous postings about building a birdsmouth. Has anyone built one for a vacationer? If so, what diameter mast did you end up with? Any changes or suggestions? I'll be using Doug Fir.Thx in advance.Andy

Having built many hollow spars over the years, I can almost do it without the math now, but with the math . . .

Technically speaking you only need a 3" round stick (foot) which tapers (starting just above the hounds) to 2 1/2" at the head. This will produce a spar that weighs 19 pounds in Douglas fur, 16 pounds in construction grade spruce or 14 pounds if Sitka is used.

Most folks use larger dimensions for their pole, usually 3 1/2" stock, with a 3" (2 3/4" would look better) at the head. This stick will weigh about 23 pounds in fur, 20 in typical spruces available at the local lumber store or 18 pounds in Sitka.

Stave thickness on the smaller mast is 5/8" and the larger mast is 3/4" (one by stock, which works out to be a handy thing). This was calculated with an asymmetrical layout for the cuts (what most folks do). A symmetric layout can save some weight, but is harder to machine.

Douglas fur makes a fine hollow spar material, which I personally prefer over the lighter spruces. It also has very good rot resistance, but special prep is necessary if epoxy is used (solvent wipe before gluing) as the glue. Masts don't need epoxy, plastic resin is just fine and a lot cheaper. Epoxy's only advantage in birdsmouth masts is it's gap filling ability. I use TiteBond III (type 1 water proof) for spars, unless forced to use epoxy.

When you pick out the lumber (you'll only need a few boards) as you go through the stack looking for straight grain, free of defects, you'll come across some that seem heavier then others. If these have good grain, pick from the heavier ones. Most of the fur, the big box stores carry is farm raised and not as good as the wild stuff. You want pieces with as tight a grain pattern as you can find. Some pieces will look much better (about 5% in a whole skid) then the vast majority you're picking from. If you look through 50 or 60 boards, trying find good stuff, you'll get lucky if you can get comfortable with a couple of them.

When picking out lumber, especially Doug Fir and Southern Yellow Pine, try to choose from wider boards. The stock that is narrower than 6" is typically from plantation grown trees. They are harvested at a young age and you cannot get wider boards than these from these trees. They will have wider grain patterns with less growth rings per inch. To get tighter grain and more growth rings you will need to select from wider boards such as 10" or wider lumber. These are from older growth trees and typically will have more than twice the number of growth rings per inch.

One of the advantages to using reclaimed lumber, especially older fir or pine shelving or siding is that they probably came from old growth timber which has considerably more growth rings per inch and is a lot more solid than the new growth available in studs and small dimension lumber. Again, pick the straightest grain possible and with as few small knots as possible. No knots would be ideal as would quarter sawn stock. But you are cutting down into narrow widths and there is little warpage if the grain is straight. Any that occurs will be take out as you clamp up the mast anyway. Just be sure it is laid out on a flat surface or you will have a permanent curve to it.

Thanks for the replys. The Doug Fir I'm using is over 100 years old. Before plastic, steel or concrete piping came into use, it was common for mines to pump slurry through wooden pipes. When I was given the wood, I saw that the edges were angled and had a tongue&groove. I just assumed they were from and old railroad water tank and I never bothered to extrapolate the angles to determine the diameter. An old miner told me about slurry pipes and that's apparently what I've got. The boards are roughly 2X4" actual by 16 feet. It's pretty amazing stuff-no knots-none- and on some the rings are so close together, I can't even count them. Should be a joy to work with. Anyways, I was going to build a straight mast. Does the weight savings justify building tapered? I know it's not that much more work but would I really save that much weight? Actually, now that you've got me thinking about it, I think a nice taper would look really good. I'll be using rope mast hoops. Will the varying mast diameter present any special considerations as the main rides up and down it? Thx for the advice.Andy

On a gaff rig stick, the mast usually doesn't taper until the hounds, but some think a full length taper looks nice (it looks lubberly to me). The logic for this is the gaff needs it's strength along the hoist length, but can save weight and be much prettier with a taper above. A racer would take it to extremes, but a cruiser isn't effected by the difference at all. Tapers are traditional and look nice. On this size yacht, it will not amount to much savings, maybe a pound. My weights above included a taper starting at the hounds.

Grommets (or gaskets if you like) look traditional, nest better then hoops and don't clank around on the pole. I don't like them, they set the sail too far aft of the mast, particularly compared to lacing or tracks. A properly tapered mast (taper above the hounds) will give no trouble with any sail attachment system. A flag pole taper (tapering from the deck) will cause problems with grommets, lacing and hoops. These problems can be over come, but again it's a lubberly thing to do to a fine and proud yacht mast.

P.S.
Can I have your left over old growth Doug. fur when you've gotten what you want out of it? Pleeassse . . .

Andrew Now here is my 2cents worth the rest of the story. Straight, tapered what ever you are talking about 1/2 inch 22 lbs 18 lbs very little difference. The trick is to get the mast up single handed. you put it up in your drive way every thing looks great, you let it down make it fast and drive to the water where you have to reraise the mast. Now while you were driving the little people were playing tricks on you. You start up every thing on the mast is tangeled and it wont go all the way up, you let it down and untangle everything you raise it again more tangles etc. The trick is to be able to raise it part way get it straighen out the continue on up. I have rigged me two triple blocks hook one end to the fromt stay the other to the bowsprit raise part way dog it off untangle the continue. When you get it pretty (in YOUR eyes) it's your boat remember the rest of the story it may help some time Bud :wink:

I'm thinking about how I'd build a birdsmouth that's tapered above the hounds. One way would be to build in 2 parts, constant diameter to the hounds, then a separate mast that's tapered above. The 2 pieces would have to be joined-not a big deal-solid piece shaped to fit the inside of both and epoxy them together. Another way would be to build the whole length constant diameter, then just plane down a taper above the hounds. Would this leave enough wall diameter at the tip strength-wise? I guess I oughta draw it in autoCAD and find out. Is there another way that I'm not thinking of? I like the idea of keeping it straight, then going to a taper.Thx.

When I built my mast I made the individual parts full length. At 4 feet I tapered the pieces with jig I made. I glued it all together and it made a natural taper above 4'. I added little triangular pieces to the stump to make it square and rounded it from there all the way up. I cut it at the 47" mark and put a octoagon shaped plug about a foot long in the open ends to make a solid piece to put the bolts through. I worked out rather well.

Because on a traditional boat you don't taper until after the hounds, doesn't mean that you have to taper it above the hounds. I built my birdsmouth mast at constant diameter all the way to the top. As you can see in the photo it only has a few feet up there anyway. (The white tip is a plug that goes into the top of the mast - it is smaller)

I felt the gaff jaws and hoops would not work as well on a tapered mast, but people taper the whole mast all the time on the Weekender. I wanted the more traditional approach. Weight is not a problem, I always lift it by myself and have no problems. With the hollow mast, I don't think it is necessary to taper it anyway.

Beautiful boat Phil. Nice shot of the mast-puts everything into perspective. I doubt I'd save much on a taper above the hounds so if I do it, it will be as a nod to tradition rather than as a means of saving a lot of weight.