For fastenings, dowels, treenails, drift bolts, spikes and screw bolts are employed. The various pieces may also be scarfed, that is, beveled together, so as to add to the strength of the joint.
Treenails are usually 1 ¼ inches in diameter and from 26 to 30 inches long. They are made from hard wood, usually locust, and are used chiefly for fastening the planking and ceiling to the frames. For this purpose a hole the scant diameter of the treenail is bored in the members to be fastened and the treenail is driven home with an air hammer. After it is in place, it is cut off, split on the end, and wedged to a tight fit. The subsequent action of the water is supposed to swell the treenail and make it fit tighter.
Although treenails are used extensively in modern shipbuilding, there is doubt as to their efficiency after the ship has had an opportunity to work in a seaway. Undoubtedly, however, they were employed in the construction of the ark, for want of knowledge of more modern fastenings, and this is a sufficient recommendation for their continued use in the eyes of many oldline shipbuilders. The chief virtue of treenails seems to lie in the fact that they work with the ship, and therefore do not present as unyielding a resistance as a steel fastening.
To supplement treenails, however, in fastening the main members of wooden ships together, steel or iron drift-bolts are used. Usually they are about 1-inch in diameter. They are generally driven by air hammer in holes bored 1/16-inch smaller in diameter than the bolt. Although the difference between the size of the hole and that of the bolt is small, they hold tenaciously, especially when the ship is new. It is said that drift-bolts driven 3 feet into fir timber hold so fast that they break in tension before they pull out. Wherever possible such bolts are driven through and clenched on steel rings in the inside.
For "sticking" the planking to the frames and other preliminary fastenings, as well as for securing the deck planks, galvanized standard ship spikes are used. Usually they are ½-inch square and 8 to 10 inches long. Screw bolts also are used for some forms of fastenings, as well as bolts fitted with washers and nuts. The latter may be taken up from time to time as required.
Transcribed by Lars Bruzelius
Sjöhistoriska Samfundet | The Maritime History Virtual Archives | Shipbuilding | Fastenings.
Copyright © 1996 Lars Bruzelius.