More on birdsmouth cuts and joints. You learn something every day. Image via.
This would be somewhat lighter in weight than a solid wood mast, but perhaps there are other considerations re flexibility etc? Someone out there will know.
More on modern high-tech sailboat masts.
I do not know for sure, but my guess is this allows the use of readily available straight grain wood to create a straight mast. Getting tall narrow trees with straight grain and the right dimensions would be difficult for a production sailboat. Wood glue is stronger than the wood, so the glue is not weakening the mast. This can be seen when performing failure tests on glue joints. The wood does not fail along the glue line. Also note the orientation of the grain is perpendicular to the way trees normally grow. My guess is this further strengthens the mast, but could be just an artifact that they are buying quarter sawn wood for its uniformity.
ReplyDeleteI hadn't even noticed the grain of the wood. Thanks, Larry, for those insights.
DeletePerpendicular grain does indeed make this more stable -- less danger of splitting. Note that one of the bits that has been cut diagonally (rather than strictly perpendicular) seems to have split along the grain already (lower right).
DeleteAll of those different orientations keep the wood straighter than just one piece can. It's like plywood's opposing grain make it very stable. Also, I bet there are no knots in the entire mast. The smaller pieces of wood are cleaner
ReplyDeleteAlso allows for cables to run.
ReplyDeleteThe excellent YouTube series about the reconstruction of the wooden yacht "Tally Ho" covers different options for mast design— discussion starts around 7:55 here (11:40 for birdsmouth jointing): https://www.youtube.com/watch?v=6afH0monV4U
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