Wednesday, June 2, 2010

Navigator work. Fitting gunwales

Here the two gunwales have been glued aft of the CB case, but are just 'waiting' at the bow end due to the lack of a good stretch of time. I found it more useful to glue half of each rather than one complete side because I want to bring the bow ends together at the same time to avoid asymmetric tension or twist.
The forward ends are mainly stressed along the horizontal plane whereas the aft ends are mainly stressed in the vertical plane. There is a significant and sudden rise near the transom which is bending against the thickest (and therefore stiffest) dimension. To alleviate this I used a handsaw to cut down the middle of the gunwales back to B7 (about 900mm) so that the top and bottom sections of the gunwale could slide against each other to take up the sheer curve comfortably. It wasn't necessary to pull any similar tricks on the remainder of the 20 x 40 strip.
The cut surfaces were obviously wet out with unthinned epoxy before thickened goo was brushed in and then the clamps applied.

There is a hint of 'powderhorn' shape as the sheerline broadens on its way forward, and I've noticed this in many previous builds. I would prefer to minimise this if I can, and when it is time to 'nuance' (I know it's not supposed to be a verb) the gunwale shape we will see if it can be adjusted with the hand plane.
It is impossible to capture in a single picture the sweetness of some of these curves as you walk around them. In this picture, for instance she looks very long and thin, but the impression from above the centre board is of a broad, beamy and voluminous shape. I only hope I can do these lines the justice they deserve. I do love drawing, and this is just 3D drawing with stringers.
The interior suddenly looks much more spacious than I had expected too, since the gunwales went on.


  1. The powderhorn shear line is a very graceful one in my opinion and developing such a shape in this design would be capitivating.

  2. Well Michael there is no avoiding it with this design unless we take to the bulkheads with a saw!
    For me, when interpreting, or re-creating someone else's curves, I think it is good to have a view about which side of the line to go...does this curve need restraint? Does this one need emphasis?
    A powderhorn shape is the domination of the side view concave curve by the plan view convex curve when viewed from some angles.
    I want to tread on the side of restraint in building a boat which has such emphatic curves already. In building the Waller, maybe the reverse was true.

  3. Hi Rob,
    I'm not a big fan of the "powderhorn" sheer (so that's what you call it) on a lot of the builds, to me it is over emphasised.

    Your interpretation is very pleasing to my eye but hey who am I to say.

    Really like the blog BTW almost tempts me to record my incoherent ramblings in the same manner......although there is perhaps already too much of that on the internet.


  4. Welcome Mike!
    Nice to hear from you in this other format, and thanks for your input.