Sunday, September 12, 2010

The Procession of The Strakes

After completing all of the preparatory work, we finally had the opportunity to begin the process of planking the craft. Although, on most craft, the garboard is inherently difficult to shape and attach because of the tight curves that it must accept, Willy’s first planks were a simple matter. This can be largely attributed to the flat-bottomed construction of the hull, not our boatbuilding prowess. However, after completing these strakes, we were faced with a new challenge. Unlike the bottom boards, which are affixed to the chine using screws, the remainder of the planks (8 in total) are fastened to the previous strake with copper rivets. Being a non-ferrous metal, copper is fairly inert in moist environments, which makes it an ideal candidate for this application. Spaced at 3½-inch intervals along each lap, we had a total of almost 400 rivets to install over the entire craft. Needless to say, we were somewhat daunted by this prospect. Fortunately, although this process does require the builder to develop a certain rhythm, it is, in reality, quite simple. The most important resources in this procedure are a willing assistant and a surplus of time, as it can be rather lengthy. Below, the system is condensed into five steps. Please recognize that, while this is a brief overview of the process, more detailed information concerning this method is outlined in many boatbuilding books.

1. Bore a slightly undersized hole in the hull at the intended location of the rivet. After the nail is inserted, this will create compressive forces on the wood that effectively seal the joint from water penetration.

2. Counterbore the hole on the outer face of the board to the dimensions of the nail head. Although this step is not necessary, it helps to seat the nails flush to the hull without scarring nearby wood through overzealous use of the hammer. In addition, we also found that some of our mahogany planks so hard that it would have been very difficult to sink the nail heads without counterboring them. If you are have softwood planking this step may not be necessary.

3. Drive the nail ¾ of its length into the pre-drilled hole. At this point, the assistant places the rove (in the rivet punch) on the opposite side of the plank. Proceed to drive the nail until level with the exterior surface of the hull. By this point, the rove should be snug to the plank’s interior. However, if this is not the case, a few taps on the punch with a hammer will remedy the situation.

4. Cut the protruding nail off, leaving it about 1/8” proud of the apex of the conical rove. While the exterior individual braces the nail head, peen the excess metal into an even, symmetrical dome, preventing the nail from retracting the future.

5. Repeat 399 times.

Although riveting is somewhat time-consuming, mundane work, if both workers are able to develop a sense of cadence, it is possible to affix a strake in little over an hour.

Close up of exterior hull rivets

Seeing as the process used for each subsequent plank is identical to the system outlined above, it would seem overly repetitive to give a detailed account of each strake. Instead, we have consolidated this task into a series of photographs, allowing the reader to witness the accomplishment of hours of our labour in a convenient photographic form.

One strake per side

Two strakes per side
Three strakes per side

Three pictures of four strakes

Done - Five strakes

Now that all of the constituent elements of the hull sides are completed, the next item on our agenda is that of bottom planking. Seeing that Willy is of flat-bottomed, cross-planked construction, we anticipate that this will be a fairly straightforward task. Tune in for the next installment soon!

Joe Lap

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