And a look at how the smaller planks are installed.
Not all the planks that are going on the boat are big
Up high in the bow, Doug and I have been removing old frames,
replacing them with new ones,
and are now replacing the planks that went over those frames. The planks up high in the bow are much smaller than the lower hull planking. They’re not as thick (1 1/4″ compared to 3″) and they’re not as wide (about 3″ vs. 9″).
When you have a smaller plank, you have a little more flexibility as far as installation goes. For one thing, you often don’t have to spile each and every plank. “Spiling” is just a boatbuilder’s way of saying patterning or copying a shape. I’ll post an entry about that soon for those of you that are unfamiliar with how it works. If you happen to come to the Wooden Boat Show http://www.thewoodenboatshow.com/ on the weekend of June 29th, I’ll be doing spiling demonstrations there on Friday as well.
When you see a plank on a boat, if it’s done right it will create a graceful, fair line. It will often look like a straight line has been wrapped around the curves of the boat, with the plank line complimenting the shape of the hull. However, when you remove a plank and lay it on the ground, you’ll find that it’s not straight at all. Sometimes the plank will curve up, down, or even form an S shape. It’s impossible to accurately predict that shape without patterning out the plank first.
You usually spile out larger planks individually. With smaller planks, you can sometimes simply divide the amount of space to be filled by the number of planks you want, and come up with a series of repeatable widths at each frame. On boats with thinner planking than the Morgan, you can actually make a master plank pattern and then cut out a set of identical planks from that pattern. In either case, planks made this way will need some minor tweaking when they’re installed. Some of that tweaking is accomplished by the process called “Edge setting.” This means squeezing the planks together when they’re put up on the boat.
Big planks can only be edge set so much. Little planks are more flexible.
With both large and small planks, the process starts with lining off. This means marking where the planks will go directly onto your frames.
We use long straight battens for lining off. The trick is to hold them on to the boat with as few nails as possible. This allows the battens the freedom to spring to a fair line. Putting up multiple battens allows you to see if there are any obvious areas where the plank lines don’t look right. It’s easy to see if your plank lines appear to converge, or if taken as a group, they don’t flow with the shape of the boat.
Once we’re happy with our lines, we’ll mark them onto the frames. Often we’ll tweak the lines a bit as we go. If a line has already been drawn, we draw the new one in a different color to avoid confusion.
Those marks will be our placement guides when we install the planks.
Down on the ground, we mill up our stock to the proper thickness, lay out and shape our planks one at a time. All of our planks are steamed just prior to installation to help them follow the curve and twist of the hull shape without breaking. The heat from the steam softens the lignen in the wood and makes the wood much more flexible. Once the wood cools it will pretty much lock into the shape we bend it to.
We use a lot of clamps when bending in hot planks to the boat.
You can never ever have too many clamps.
After the plank has cooled, it’s marked, drilled, and fastened with galvanized spikes.
And so it goes, one after another, making sure that the mating surfaces are as tight as possible.