Thanks, David,
I made that typo while correcting another one...
About Ingeborg’s mast (150mm x 5mm 6082-T6):
It appears to be plenty, both strong and stiff enough. I can hardly notice any bending of the mast, neither from the cockpit, nor on photos. I would be tempted to use this dimension even on a boat approaching 3 ton displacement *): The fine thing with an unstayed mast is that it shows the load. In case it shows signs of bending much, close to deck, all one has to do is to unstep the mast and insert a three-meter long inner tube. This does not have to be a close fit. Just grab the best one can get, and then shim out the inner tube with 3-4 ‘waistbelts’ of glass tape, set in epoxy. One even doesn’t have to glue that inner tube in place. Just fix it with a couple of screws next to the mast step to keep things together while stepping or unstepping the mast. That simple measure could easily beef up the mast strength with 50%.
Another thing with Ingeborg’s mast:
It doesn’t tremble. Malena’s, and in particular Johanna’s mast (both wooden) could tremble in a breeze. It was not during sailing, but in harbour, with the sail down and with me down below. The frequency seemed to be in resonance with my nerves, somehow, and kind of scared me, no matter how safe and secure the boat was. Needless to say, I tried avoid this by altering the tension in the halyard and lazyjacks, but in the end it appeared that the frequency had to do with the mast alone.
On Ingeborg, the mast can also oscillate in strong winds, but the natural frequency is much lower, so doesn’t feel annoying at all. My guess is that the softer material and smaller diameter of the lower mast plays in here. Bad vibes verus good vibes...
Epoxy:
I used West Epoxy. This has been used on three boats, Edmond Dantes, Frøken Sørensen, and now on Ingeborg. The epoxy joint on Frøken Sørensen’s yard was thoroughly painted (2013) and looked good last time I saw her. On Edmond, that epoxy string was never painted, so bits of it started coming down after just a couple of years. Since fitting a string of Sikaflex or similar would be much simpler, I would rather recommend that method, today. The two bolts at each end of the yard takes the main shear loads, and the two tubes are firmly held together by the lashing of the halyard blocks and by that stitched-on PVC mast-padding, so the choice of glue is hardly critical, me thinks.
Arne
*) No I would not! I would rather downsize than upsize if were dumb enough to sell Ingeborg.