I mentioned in my previous post that there was one station point that just didn't line up with the curve of the side panels. I quintuple-checked my measurements of that point and its neighbors, of the station lines themselves, and of all the figures on the plans related to any of these items. In particular, I checked and rechecked my math, because I'm working in Imperial units, and it can be easy to go awry when adding unlike fractions. At every step of the way, it all checked out except the location of that point on the curve.
Searching online for phrases like "Wharram Melanesia error" or "Wharram Melanesia station line" turned up nothing obvious, either. I had just about decided to email the Wharram office and see if they had any ideas, when a thought occurred to me. The Wharram folks, being Brits, work in both metric and Imperial units, and the plans are marked with dimensions in both systems throughout. Not having access to a good construction tape measure with metric markings, I've been using the Imperial measurements. But what if there was an error in the conversion?
I checked, and the numbers didn't match up. The plans give the depth of the side panel at that point as 13 3/16" (around 13.19") or 351mm. But 351mm is equivalent to around 13.82", not the 13.19" indicated. When expressed as fractions, it's easy to see the potential for a typo in the two numbers - 3, rather than 13, 16ths.
(In case you're reading this after searching for an explanation for the errant point on your own Melanesia, dear reader, the point in question is the side panel curve at the second station line forward of the center joint.)
I checked the position of my curve at the spot in question, and it came in around 13.7" - about an eighth of an inch shorter than the figure I'd just arrived at. I'll need to redraw those side panel curves with that station point included to make sure I don't have gaps in my hull at those points. But that's only a few minute's worth of work. And the discrepancy between the curve as I drew it and the curve it should be is only 0.125", rather than the 0.625" error.
Further, the error would have required a sudden concavity in the middle of a convex curve. It would be very difficult to render that curve correctly; with the new figures, I need to produce a slightly greater convexity at that point, which is much easier.
So that's a big relief. After figuring out this problem, I traced the stem and stern posts onto the plywood, and figured out a way to sketch in the 13.75" radius curves for the deck beams. At this point, the transfer of curves from plans to plywood is complete. I hope to begin cutting the panels out tomorrow. I need to order epoxy, fiberglass tape, etc., so that I'm ready to begin putting it together when the cutting is finished.
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