After losing a plank due to not steaming for some considerable twist (see previous post), I machined up two more Huon Pine planks 8' wide and 13' long for the second round of planking. I cut the planks roughly to shape, tapering to about 2" at the forward end, and put each in turn into a heavy-duty plastic sleeve which I then attached to my steam generator. Each plank in its sleeve was then lightly clamped on the boat. After an hour of steaming I began to wind in the clamps and added more and the plank easily twisted in to lie against the ribs. Have a look at this video I made of the process. Once each plank was cool, I removed it from the sleeve and clamped it back on the boat to let it dry. The next day I began to trim each plank to fit, starting with spiling to get the shape to fit against the previous plank, then planing the bevel to allow for caulking, then marking the upper edge and cutting and fairing it with hand plane. Each plank needed several goes on and off the boat to get it right, including some shaping of the back of the plank to fit against the slight curve of the ribs at this point (and corresponding slight hollowing of the outside). More shaping was necessary on the Port side plank, very little on the Starboard side. I had selected the orientation of the grain so that the inside of the tree was against the ribs so that the tendency of the plank to warp away from the centre of the tree would help the plank to fit. The Starboard plank responded well because it was closer to flat-sawn grain, the Port plank was almost quarter-sawn and didn't warp much. I had machined the planks to 1" to allow for hollowing and rounding, so on the Starboard plank I had to take 1/8" off the whole of the outside to finish the plank at 7/8". At the moment they are clamped on after a final fit and drilled off for the fastenings. They will be removed and primed before being fastened off.
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AuthorIan Smith, Boatbuilder (ret'd) Archives
January 2024
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