Hi good people,

Two years ago I started building ...
" .. today I got 4 of the 5m alu-keel up and hanging in strings attached to each end. This setup does not reflect how it will respond in water, but .. gee, it's SOFT. Awful soft. My instinct tells me that it's too soft to act as the central and only 'rigid' structure to 'hang' everything else up on.
Has any of you any idea weather I'm out on a too soft limb here?
The alu-tubes are 30mm ø-outside 26mm ø-inside. They are attached by inlined tubes 24mm ø-outside 22mm ø-inside - the 2mm discrepancy covered with tape, but the bending of the long assembled tube is not particularly focussed here, it appears to be the overall elasticity of the collective tube. "

This lack of rigidity stayed on, and after a season on the water I've come to know why Eric the Red called his ship "Ormen hin lange" (the long worm). Knowing that the inner tubing at the assambly-points are only half dimensions of the outer keel, I've always felt it as a weakness. I pop this mail because I think that I've eventually overcome this shortcomming. I'm dissappointed that I couldn't figure out the solution, it came somewhat haphasardously:

Parallel with the keel I've added (in another boat-construction) a long upper tubing/stringer following the center of the kayak. Along with the cross-section ssupports the two tubes constitute a 'plane in space', perpendicular to the watersurface, vertical and following the length of the boat (it's mirror-plane). By stringing the two tubes together tightly, the setup now constitute a vertical support-plane, and not just a single rigid line in space. You may have to read this once more to 'see the light'.

https://onedrive.live.com/?cid=382E99B169B58267&id=382E99B169B58267%21258&v=3
this photo is taken from below, with the kayak hanging from my cieling. The keel assambly-point is visible (the dark stuff above is velcro). The 'foot' of the cross-sections has been supported with two extra sets of plywood so the section stays upright and perpendiular stably. Now, the broad velcro-band 'supports' the keel. Right?
No screws or punching holes anywhere - and not really any extra as I need the strenghtened upper stringer to make .. a maritime assending.

https://onedrive.live.com/?cid=382E99B169B58267&id=382E99B169B58267%21256&v=3
This is the solution that is perfect if you'r constructing a u-boat. Anyway, In the cocpit there's no way that I can provide the 'central plane support' - and as it's almost below my hinie .. and because I would like this particular boat-construction to have margin enough for some robust fun on the water .. I'll just swallow.

Well, I found this pertinent as for the rigidity. I look forward to present this new boat and the ideas behind later on.

Cheers