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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In August I spiled, cut and fitted both garboards, the lowest planks fitted to the rabbet in the keel, from the stock of Huon Pine I have had since 1983. I had only one board of 8"-wide stock 19' long, so the other side was scarfed together from a 13' and a 7' board. All boards were spiled and cut close to finished shape and steamed because of the serious twist of about 45 degrees along the length. Without a steambox long enough, I slid each plank into a sleeve of heavy-duty plastic and attached the hose from the steam generator to one end and tied up the other end. Each plank was fitted roughly in place on the hull, and after an hour of steaming I started to clamp them in place, winding the clamps in gradually to get the twist, until the whole plank was against the ribs and keel rabbet all the way along. The Port side which was to be scarfed was steamed in overlapping sections before scarfing, as a glue joint would not take the heat and moisture of steaming. The next day I undid the clamps and slid the plastic sleeves off the planks. Both sides had retained most of the twist, enough so that easy hand pressure was enough to push the planks against the ribs and rabbet. I clamped the one-piece Starboard side back up and began to fair the keel rabbet and then scribed the bottom of the plank to fit the rabbet. I then marked and cut the scarf joint and clamped the plank in place with WEST System epoxy glue in the joint, with plastic sheeting behind it to prevent it sticking to the keel. once the glue was dry, I concentrated on shaping the back of the plank to the slight and ever-changing curve to allow it to sit tight against the back rabbet and ribs, as well as fine tuning the fit against the rabbet. The plank was off and on the boat several times before I was happy with the fit, then the caulking bevel was planed on the bottom edge, and the upper edge faired. The last time it was clamped on the boat I marked and drilled for all fastenings, then I primed the rabbet, back rabbet and lower ribs in the way of the plank as well as the back of the plank and clamped and screwed it in place using temporary chipboard screws. All the remaining planks will be permanently fastened, but the garboards will be removed once planking has finished so that shavings can be easily swept out once deck and interior work starts. A month travelling in the US including a visit to the Port Townsend Wooden Boat Festival and a week sailing in the Australia-USA Sandbagger Challenge in Annapolis intervened, but once home I repeated the procedure for fitting the Starboard garboard, also with temporary screws. I then spiled the stealer plank which is just under 8" wide at the sternpost rabbet and just under 2" wide about 12'6" ahead of that, cut, fitted and primed the Port side. Clamps pulled the plank in without recourse to steam, but this was a mistake. During final fitting the plank split with a loud report, into two planks. Eight hours and 13' of 8" plank wasted! Serves me right, if the plank doesn't relax fairly easily into the twist, steam is needed. I have two more suitable planks, so I'll start again, but this time I will steam them.
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AuthorIan Smith, Boatbuilder (ret'd) Archives
January 2024
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