Monday, June 7, 2010

Navigator work: gluing gunwales

This bit is really very sculptural. From above you have a fairly simple pair of convex curves forming the length and breadth of the boat. From the side you have a long sheer curve, dipping from the transom to a low point aft of the middle and then slowly rising much higher than before, when it approaches the stem. But as soon as your position changes from these theoretical perpendicular ones (which only really exist on paper, because our vision is never really comparable to a 'projection') the shapes become so complex as they interact that some of us find ourselves wandering in circles, tripping over clamps and off-cuts, trying to take in the totality of the edges of volume and building up our own three dimensional construct in our little brains. Taking it in is one thing, but forming a judgement about which bits aren't working so well is quite another.

One of the benefits of building in this method is that there are layers that go over layers, so lines that worry you can be finessed a little now, but not too fussily, in the knowledge that further refinement can happen later at a new stage. So the side view of the sheer may have some little bumps or irregularities that bug you, and the high spots can be planed off, but the planking will go over all that anyway- and then the rubbing strake, and each of these can improve- or not- your feelings about that line.

In the photo above, I've just started to bevel the tops of the gunwales to the angle of the side deck, but in doing this I'm also trying to form a view of the line as a whole from several viewpoints, and will work some bits more than others to remove the visual offences. Now some people will read this and think; "why doesn't he just make the boat, and stop analysing?' And the answer to that is that I love lines, and mucking about with lines and edges is just as important to me as having a boat. I guess I've had more than five decades working with lines of one sort or another, but I'm an absolute beginner at boat building.

One of the bits of line that I'm not happy with is at bulkhead 2 on the starboard side (top pic). You can see there is a little clamp fixed to the spot near the top right of the pic. As the gunwale goes past this bulkhead the curve is a little 'hard' or sudden. I can't measure that, but I can see it and the gunwale will be planed back to make that curve as fair as the one on the other side. There's maybe only 2-3mm in it, but that curve would bug me forever, visible from the helm.

This picture says something about the 'powderhorn' shape that worried me in the previous Navigator up-date. A more front-on view has a more pronounced powderhorn, and that is inherent in the design and it doesn't worry me. But this view shows a secondary one that is a result of a wobbly gunwale shape, and I can make it nicer. If you follow the gunwale from transom, down to the low point then up, you will see that it comes up too suddenly to a false peak, and then flattens out on its way to the stem, dipping again, ever so slightly in the process. The extent of this changes as you move around the boat. A lot of it will disappear just by planing the top surface down to the correct deck angle, but knowing what I'm aiming for will help me target my planing, to be emphatic 'here', and restrained 'there' until the line flows simply from one end to the other.

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