technique is called clinching. It is the sort of thing which used to be found in Scandinavian-built boats but even with iron nails, on the lands, they were usually properly clenched over roves. Nails fastening timbers were sometimes turned over, particularly where removable bottom boards were to rest on the timbers. However, it was possible to tread the bottom boards onto the clenched nails and where marks were left, gouge out recesses to accommodate the clenched nails. Screws were used for fixing the ends of the strakes to apron and transom and in later times, knees to gunwale and thwarts, but traditionally, this last would be done with a clench bolt or a large copper nail, clenched. Adhesive, notably epoxy. Traditionally, lands were neither glued nor was anything used to bed them. The garboard was bedded onto the hog and keel, and the ends of the strakes onto the stem and apron using a mixture of white lead and grease. During the World Wars new techniques and materials were developed by the aircraft industry. By the mid-1950s, these were well infiltrated into the boatbuilding trade. New boats in classes of racing dinghy with clinker hulls were built as glued clinker boats. The basic construction was the same but ply planking was used and the lands were glued with no fastenings, except that the ends and garboards were still screwed to apron and hog. The need to prevent the splitting of the planks was removed by the use of ply so no timbers were used. Except for a light gunwale and wide rubbing strake, the longitudinals were omitted too. A short thwart rising and knees were glued to the planking. These boats were all decked and that is how adequate stiffness was achieved. So that the liquid glue could be laid onto the land before the next plank was assembled onto it, they were built upside down. Fastening the centre-line structure In the last few years of wooden boat construction, glue and screws took over, but until the 1950s, the keel, hog, stem, apron, deadwoods, sternpost, and perhaps transom would be fastened together by bolts set in white lead and grease. There are three kinds of bolt used: of which, nowadays, the screw bolt (i.e. threaded bolt), with its nut and washer, is by far the most common. The second type of bolt is the pin bolt or cotter bolt, which,