All plank fastenings are driven through holes bored with an auger. Up to within the last year or so these fastening holes were bored with hand-operated augers, and the regulations for proper sizes of holes (based upon experience) stipulated that holes should be bored 1/8 inch (for 1-inch fastening) smaller than fastening. This insured that fastening would fit tightly into hole and hold properly after it was driven. This regulation for hand-bored fastening holes is absolutely sound and correct, but when it is applied to machine-drilled holes it is incorrect and results in fastenings being loose and insecure.
When a fastening hole is drilled with an auger attached to an air-driven tool the auger should be one or two sizes SMALLER than the one used for boring for same sized fastening by hand. The smaller size auger is necessary when a machine is used because the higher speed of rotation, coupled with the difficulty of holding auger perfectly vertical and steady, nearly always causes tyhe hole to assume an oblong shape and to become slightly larger than size of auger.
Whenever a fastening hole is to be bored wit a machine-operated auger use an auger one size smaller than is specified for hand-operated augers.
Two kind of fastenings are used for connecting planking to the frame; wood (called treenails) and metal (copper, composition metal, or iron), and the fastenings can be spaced either single, double, or alternate single and double.
By single fastening is meant each strake having one fastening of each kind into each frame; by double fastening is meant each strake having two fastenings of each kind into each frame, and by alternate fastening is meant each strake having one fastening of each kind in every other farme and two fastenings of each kind into each frame between single fastened frames.
On Fig. 45 is shown sections of planking with single, double, and alternate fastenings through each strake. Before the advent of steel ships the larger wooden vessels were nearly always double fastened, medium-sized ones were double fastened above water and alternate fastened below, and the smaller ones were alternate fastened above water and single fastened below. This practice was an excellent one and with this modification should be followed in these days: Whenever fastenings of knees, clamps, shelf, pointers, or riders pass through frame and outer planking the planking fastenings should be only sufficient in number to draw planking to its position against frames.
The reason for this modification is: The through fastenings of parts mentioned must have a clear passage-way through frames and must have proper amount of solid wood surrounding them. If double fastenings of planking are driven in places where other fastenings must pass through, one of two things may happen, -- either the additional fastenings will cut an excessive amount of wood from frames and thus weaken the frame, or else the fastenings of planking will interfere with knee and other additional fastenings.
It is well to bear in mind this important fact -- treenail fastenings resist transverse strains better than metal, but the metal will better resist direct separation strains. It therefore is apparent that a wise combination of the two kinds of fastenings is most desirable.
As the inside planking (ceiling) is not laid at the same time that outside planking is a certain proportion of both outer and inner planking fastenings must be driven into frames only.
The usual manner of fastening is somewhat along tehse lines: The outer planking is first fastened with a certain number of metal fastenings that pass through planking and into frames for about two-thirds of their depth, a certain number of treenail fastenings are then driven through outer planking and frames and wedged tight. These fastenings are only sufficient in number to securely hold planking in position until inner planking (ceiling) is wrought.
The ceiling is first fastened with a minimum number of short fastenings that only pass through ceiling and into frames. After ceiling is in place the planking fastenings that go through outer and inner planking and frame are put in, the metal ones being clenched and the wood ones wedged.
To fasten butts through bolts, treenails and short welts are used. Butts are usually cut upon the middle of a timber and are fastened with one treenail and one short bolt through the butt of each plank into butt timber (timber butt us cut on) and one through bolt, called a butt bolt, in timbers nearest to butt timber.
On Fig. 46 is shown a properly cut and fastened butt and below the illustration are given rules for spacing butts.
Now a few words about wedging treenails.
After treenails are driven their ends are cut off flush and wedged with hardwood wedges, the wedges serving the double purpose of expanding ends of treenails and thus increasing resistance to separation of the two or three pieces of material that the treenails fasten together; and of caulking the ends.
Very large treenails used to be caulked with three wedges forming a triangle, and small ones with two wedges crossing each other at right angles, but in these days the practice is to use the cross wedges on very large treenails and a single wedge on the smaller ones. Treenails must drive tight, meaning by this, be driven through holes that are somewhat smaller than the treenail. On Fig. 47 are shown a number of treenails ready to drive.
Transcribed by Lars Bruzelius
Sjöhistoriska Samfundet | The Maritime History Virtual Archives | Shipbuilding | Fastenings.
Copyright © 1996 Lars Bruzelius.