Unwinded – July 2018

“It’s straight.” Axel holds a stencil made of thick veneer to a row of wooden blocks which are screwed to MARABU’s inner side in the middle of an already removed rib.

I look at this from the opposite side and am firmly convinced that apart from the curvature from top-to-bottom to bottom-inward there is nothing “oblique” about the groin.

In a relaxed state without bending along the fuselage, I can see that the template is rounded on the side of the stop.

The boatbuilder now has to explain this to me in more detail and points out another special feature: the blocks are not cut at right angles to the planks on the stencil side either, but have a slight bevel.

Since Josef Martin decided to replace the frames originally made of steel in wood, a method is to be used which combines the modern form gluing of veneer layers and the process of steaming solid wood parts, which used to be common in construction: an “Unwinding”.
The new rib is glued directly in the ship with the help of the stop made of precisely aligned wooden blocks – initially with a separating foil – and thus immediately absorbs all distortions of the straggly hull at its position.

Later adjustments with the plane are largely omitted, the visible sides of the frames elegantly follow the lines of the ship. The curves of the template, which are transferred to the veneer strips to be glued, are created by the tapered shape of the hull at the bow and stern. The greater the difference in fuselage width between two adjacent frames, the clearer the curve in the two-dimensional view – in the middle keel area there is an S-shaped curve.

Astonished and admiring I take note of the simple means with which the boatbuilders construct or position the stop for the stencils. No computer program (as e.g. for the new construction of the 75er “Schärenkreuzer”  according to old Estlander plans in 2017) has to calculate the necessary geodetic lines and also the multi-line laser (which would only shake around with the smallest movement anyway) remains in the cabinet.
All Axel needs are several long straighteners, a pencil and a good eye. Two slats are fixed at approximately 90° to each other, then one horizontally at the frame head, the other vertically at the frame foot.

The two touching edges are aligned along their entire length by taking a lateral bearing, and in this way projecting an imaginary straight line onto the side wall. The third batten is now also aligned at this “covering edge” and placed one after the other like a ruler on each of the previously roughly positioned stops. Both the exact position and the inclination of the stop timbers can be precisely marked with it.

Complicated and tricky? No, Axel doesn’t think so at all and grins mischievously: That’s simple geometry and with a little experience and skill it can be done in a quarter of an hour.