Sunday 14 June 2015

A milestone

Plank #1 (starboard garboard) is fitted and glued! This is an important milestone in my poject as it proves that the plank shape that I had pre-cut by CNC waterjetting using 2D  templates derived from the 3D model of the hull is actually spot on!

I had pre-validated the plank shapes through a 1:8 scale model, however all through the building of the boat's frame I was wondering whether it would really work as well in 1:1 scale: the boat's length is such that a small error could lead to trouble.
In the "traditional" building method proposed by the designer, the planks are spiled from the boat's skeleton composed of the floor, the frames and stringers erected over a strongback. In my case the planks are cut even before any part of that skeleton even exists. The risk therefore is that small inaccuracies in setting up the boat's strongback, frames and stringers would bring to disaster when fitting 5.8m long planks; and would the 3D unrolling of the boat model to yield the 2D templates really work on the boat's full length?. One of my biggest fears was off course that a plank would fit at one end of the boat and then gradually diverge from its intended shape, both due to inaccuracies in the boat's frame or in the 3D -> 2D CAD conversion.
As I said the 1:8 scale model sure helped to reassure me and provided the grounds to proceed having the 950€ worth of plywood CNC cut.... however seeing the real thing, the garboard plank fitting nicely all along the boat's length, sitting to the millimiter on the stringer and respecting the intended overlap with the following plank is so great to see!
I now look at the ready cut planks and think to my self: this can go quite fast now!

Sunday 7 June 2015

When the going gets tough ....

Many Pathfinder builders have commented on how daunting the task of beveling the stringers feels when one first approaches it. Undoubtedly as one fits one by one the 20x45 mm thick pine stringers, forcing them to fit into the notches in the frames, screwing, clamping, tying ropes , the mind also fast forwards to the following step of beveling them. And one wonders: how the heck am I going to do that ... ? The question applies mostly to the garboard stringer, the one fitted to the flat floor of the boat. That needs a lot of material taken off its original 20x70mm section to create a following angle all along the boat's length.
Some Pathfinder builders have called this step "the battle of the stringers" ... and one can clearly understand and share that denomination once the task of cleaning up the workshop after the beveling takes place.

The planks' stringers can beeasily taken care of by power planer followed by a hand plane, checking with a ruler/square edge along the way that the bevel angle is suitable for the plank to sit nicely.
The garboard stringer on the other hand requires a bit more of a hefty arsenal. In the following picture some of the tools I've thrown in the mix are shown...

The circular woodsaw fitted to the angle grinder may never belong in any good practice shown in an HSE manual however it allowed to "eat into" and cut through the stringer to a pencil line drawn beforehand. The line is drawn by fitting a flexible batten with clamps on the frame to reproduce the twist and orientation of plank #1.

Once the first cut is done, it is time to throw everything at it in order to separate the unwanted material: from chisels to handsaw to hammer.

In order to finish off the surface I folllowed other builders advice and used a sanding disk fitted to the angle grinder. An electric file was also handy to tackle those areas difficult to get at... mind you the whole problem in shaping  the garboard stringer is its accessibility or lack thereof.

Once it's done, it's done though and one can look forward to the exciting next step: planking!

Actually, I stand corrected. The following step is cleaning up the mess: wood chips and fine wood dust sprayed all over the place by the angle grinder....