Stavanger, Sunday

Shear tension and shear load; just google Shear Load and you will find it explained. Anyway, don’t make a big issue of this; I may well be wrong here so you could fit the split where you like. My hollow masts have the join in the fore-aft direction

You may well scarf join the battens to make use of its tensile strength. If you use epoxy glue, the scarves need not be perfect. The batten filling the gap should not be bigger than necessary so don’t open the gap too wide and deep with the router.

The link to that scanned sample: If you go to my personal photo album, it is the last photo.

Arne

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                                                                       Stavanger, Sat.

The position of the split is not that critical, but I guess I would put it in fore-aft direction as the shear tension (as a result of the weaker side forces) will be working on the re-glued split.

I haven’t used the split method on my masts, but I closely observed the drying process of a friend’s 32cm mast with that split cut in it. The owner measured the width of the split on 3 positions every week, and noted the value. When the gap stopped opening any more, he opened it to an even gap with a router, inserted a tube for electrical wiring and finally glued in battens to close the gap. No splits more than nail-thick could be found on that mast (easily filled with preservative oil).

Now I just scanned an inch-thick sample of Malena’s first solid mast. It shows what happens if the mast dries too fast and without that tension-relieving split cut into it.

Cheers, Arne

Thierry

This isn’t rocket science. Just measure the diameter of the mast on 4-8 places ("waypoints"). Then you start cutting in the thin end and adjust the dept of the cut at each waypoint. BTW I would shape the trunk into a mast first and make the cut afterwards. Thickness of the blade is not critical. The cut will open fairly unevenly as the mast dries. When the cut doesn’t open any more, after a few months, the mast is supposed to be dry enough.

Good luck.

Arne

PS: As long as it is cold and the bark is still on the log, the wood will not split, so you are not in such a hurry. Just don’t debark the log before you are about to shape it into a mast. Then make the longitudinal cut right after that.