No, that wouldn't work, it's bending strength you're looking for, not compression strength. You need continuity from top to bottom. If you can get enough of the teak, you could scarph it to get the full length, but it seems to be making hard work of the job, when 30 x 100 pine (pinus silvestris) will do.

From Oy Finnlumber Ltd:

"Finnish sawn timber, based on a raw material grown in the Northern part of Europe, is known for its good quality and dense annual rings. Therefore the Finnish stress graded goods reach high strength classes and can be used in demanding end-uses."

Jami Jokinen wrote:

I'm also fiddling around with the planning of the tabernacle. I was adviced using about 22x100 mm teak, which seems to be very hard to get.

As an alternative, I was thinking about 30x100 mm birch-plywood (considerably stiffer than general plywood), cut in a way that gives the best vertical stiffness and which would be epoxied. Any thoughts?

The horizontally grained plies would be doing nothing useful, just adding weight. Teak is not necessary, a local hardwood can be used. Is there any oak in Finland? Or other reasonably durable hardwood? If not, I would prefer slow-grown, close-grained softwood over plywood.

The mast issue is on it's way next. If I stick with my draft #2 (below), the mast should be around 6100-6300 mm above deck. The mast will probably be set on a tabernacle, unless I find it easy enough to step it without one easily enough every time (the boat is trailered to and from water on every sail).

The aluminium tubes I can get my hands on here, are 6000 mm. I will probably go for a hybrid with a tapered wooden topmast, maybe 1500mmm or something like that. That would mean shortening the aluminium tube with maybe a 1000 mm.

A 100mm/4mm tube is the obvious choice, I think. The 17 ft boat has a draught of 500kg and a ballast of 120kg - which I'm about to increase to maybe double of that. I think the hull shape has a significant role in the stability of the boat, because it is not easy to capsize it with the modest ballast and shallow keel. I like sailing in rough conditions and sometines quite choppy seas.

I'm a bit worried about the weight of the mast, but I suppose 100mmm/3mm is not a safe option?

Jami Jokinen wrote:

The grey dot is the estimated center of effort of the BR. Arne's sail drawing is missing the central of effort, but I think it's right under the SA of the text "Total SA=...".

The CE of my master sails sits about 1% of B forward of the middle, somewhere between batten 3 and 4.

Thanks!