In February 2021, the Wooden Boat School in Brooklyn Maine USA released the first of a series of on-line videos: “Mastering Skills with the Wooden Boat School.” In these videos mainly led by Greg Rössel, he gives step by step instruction on individual aspects of wooden boat building. The $49.95 annual subscription, gives access to all the videos to date and to new ones coming out each month. Greg Rössel is an excellent teacher and I recommend his book “Building Small Boats” as well as these videos.

The episode on lining off a hull was released a few months ago and has been a very useful source of advice as I come to lining off the hull of my dinghy.

Lining off is the process of tacking battens to the stem, transom and moulds/frames to establish the positions and sizes of the planks to be fitted. The Americans use the term strake for planks, hence their term lapstrake instead of clinker for this type of construction of overlapping planks/strakes.

There is a lot to take into consideration in lining off!

The Garboard is the lowest plank – the first to be fitted – and this must be wide enough at the stem to establish a sweeping curve and provide room for the greater number of fixings at the stem to hold the plank in place (the tension on the fittings here is greater than elsewhere because of the degree of twist and curvature at the forward end of this plank).

Having determined the position of the garboard plank, it is time to line out the remaining nine planks.

At the stem, the width of the planks above the garboard should be equal, except for the uppermost plank – the sheer plank/ sheer strake – which is usually a little wider than the planks below for aesthetic reasons. The strip of wood that runs along the gunwale – the rubbing strip – gives the illusion that the sheer strake is narrower than it really is, thus the height of the rubbing strip has to be added when determining the width of the sheer strake, so the plank does not appear too thin. In addition, a slightly wider sheer plank is aesthetically pleasing.

The planks should be fairly evenly spaced along the widest part of the boat, but slightly narrower going around the turn of the bilge, and slightly wider where the curve of the hull is less (at the bottom of the boat). That’s why the plank next to the garboard is often called the board strake.

Dividing the curved length of the stem, transom and the moulds can be done using a tape measure and dividing the measured length by the number of planks. However dividing these measurements is not easy, especially if imperial, and anyway errors creep in when marking out. This is where the technique, described by Greg Rössel as “The Amazing Diminishing Pyramid” comes in. This is ancient geometry, used in determining perspective in drawings and design, perhaps better shown than described:

In practice, there is no point in doing this for all the moulds. Equal divisions are only necessary at the stem, and in the middle of the boat they serve as a guide only because the plank widths are adjusted to the degree of curvature as mentioned above. Once the lining out battens are nailed to the stem, transom and middle two moulds the battens adjust themselves to produce a fair line … like this:

My next job is to mark the top edge of the battens on the stem, moulds and transom (a shallow saw kerf on the moulds, and red biro on stem and transom). Then I shall remove the battens and use till roll tape to transfer the marks on each of the moulds and transom to the other side; fit battens to the starboard side; and check for fairness.

There’s a Greg Rössel tip for transferring the marks at the stem I shall describe later.

By the way, I had the devil’s own job getting the garboard plank’s batten to run fair between midships and the stem. Thanks are owed to Matt who helped to tweak the batten to give it a fair line! Thanks too to Mark and Sylvia for their help with this phase of the build.