Strake - Assembling The Strakes

Assembling The Strakes

Two methods used to plank a wooden hull are: carvel in which the edges of the strakes butt against each other, using an internal frame structure to maintain the boat's shape and clinker in which the adjoining strakes are held together on an overlap. Their varying widths and angles of overlap determine the hull's shape.

In the former form of construction, one more traditional in the Mediterranean than in north Europe produces a relatively smooth hull surface but needs caulking to make it watertight and it is relatively heavy (due to the mass of the required internal framing). Carvel boats are planked up onto pre-erected frames which become part of the boat.

The second method is clinker. It is traditional in the north and produced relatively light but strong boats. Normally, the boats are built from the garboard up so that the upper plank overlaps (aka hems) the lower on the outside. That overlap is known as the land and it is held together by copper rivets. In the twentieth century, the boat may have been built of plywood and the strakes glued together without clenched nails. Medieval boats are more likely to have been riveted with iron nails. To rivet the lands, the planks in the two adjoining strakes are pierced, a nail inserted from the outside and a rove or rove punched over the inside end of the nail. The latter is then cut off a little proud of the rove. The nail is then clenched over the rove.

When the shell of the boat is complete, the strakes are stiffened by the insertion of steam-bent timbers. These too, are riveted to the planking through the lands. The timbers, which are sometimes miscalled ribs, spread the load on the strakes and tie them together reducing the tendency of the relatively thin strake to split. With glued ply clinker construction, the timbers are unnecessary.

At the hood-ends of the strakes, where they approach the stem, they are let into each other with geralds (aka chases or gains). In these, the land of the lower strake is tapered to a feather edge at the end of the land where it is supported by the rebate formed by the apron. The strakes then meet the stem flush, which is also referred to as being hooded.

Steel ships may be plated as clinker-built vessels but more usually, they were built with strakes alternately in and out. The modern method is to butt-weld the strakes to each other as well as the plates within them, end to end. This leaves a smoother finish and is lighter.