Bird's-Mouth

[mrthethird]

Wish I woulda thought of that :oops: . I had to cut out half-slices where the build up was supposed to go....Still works fine, though. Had it through a couple of good blows, no problems 8)

[PAR]

Among spar builders and designers, there has been some debate about Sitka verses Douglas fur in hollow spars. Traditionally Sitka is favored in solid spars, but the wise designer can suggest a harder lumber in hollow sticks. Ash, Douglass fur, plus others have been used, as well as some spruces and other evergreens. Compression strength is key in a box or birdsmouth pole. The ability to hold fasteners, weight, rot resistance, aging traits (checking, splitting, etc.) are some of the other factors that weigh in.

[Barry Pyeatt]

I'll toss in a couple little tips I've picked up along the way as well. Using the "half spar" building technique that Charlie uses is not only a very practical way of building but it also allows you to get the spar fashioned, plugs installed where needed, but allows for interior wiring, rigging and coating with a finish to protect the interior surfaces. Very hard to do that with a solid built spar. Just be aware that the birdsmout layups will take any shape that they sit on. To make them straight, you have to plan for them to be straight and check it close as you lay it up and let it sit to cure. By the same characteristic, you can make a nicely curved bowsprit with a little attention to shape. 8)

I've found that like others mentioned, that the wood of choice seems to be either Douglas Fir or Sitka Spruce in this part of the world. Selection of an appropriate wood is more important than with other parts of the building process in many respects. Although you end up with a lot of little strips grain runout makes for a weaker stave. It is hard to find good Douglas Fir until you go to wider boards where you get into a better quality lumber than the 2X smaller dimension stock. Tight, close, straight grain makes a huge difference in the end result. If you go through a stack of 1X10 or 1X12 you might find one or two good boards for this purpose. Scarfing together shorter lengths of good wood makes finding suitable lumber a lot easier task.

I've seen several mahogany hollow birdsmouth mast fabricated and they are holding up pretty well, sure are pretty. Ash, White Oak and Elm have been used as well in this area. There isn't a huge difference in weight between any of them. I would focus on masts and perhaps bowsprits, Not much significant difference in weight savings on a gaff boom and on a main boom I've found that the extra weight in a solid wood boom is better than a lighter birdsmouth version. I've made up several, all from quarter sawn Doug Fir that have held up well for many years. Two of them were long enough that working with shorter lengths of lumber made finding good tight grain wood possible. Both of these used old growth recycled lumber from library shelving. The 20-35 growth rings per inch made nice material to work with. Might even change over and make up a birtdsmouth mast for my own Weekender in the future. Fun projects to do.