Treenailing-off. - One thing which should be particularly attended to by the master or foreman at this time, is to see that all the augers for any particular part of the vessel are exactly of the same size; for if this is not the case, it will be almost impossible, without a vast deal of trouble, for even an expert workman to drive the treenails so well as he would do with ease when the holes are all bored with augers of exactly the same size.
The treenailing-off is very frequently performed by inferior hands. The operation, though simple, being one whose effects are well known to be very important; therefore we may suppose that it is more an error of the will than the judgement to slight this part of the work. There are few builder or their foremen who are not aware of the advantage of having the plank well fastened; for my part I would have the best workmen to execute this part. The treenails should be made from the most durable quality of timber, English oak being considered very suitable for this purpose; and real good well-seasoned Dantic or Memel fir for a fir-bottomed vessel. The treenails should be made and drove with accuracy and attention, so as to be tight into the plank and timber; for although the framing and bindings be the best possible, yet if the treenails are carelessly driven, or be of bad quality, such a vessel will soon become losse; and as the bindings will be little assisted by those of the plank, they will also soon become loose, as they will suffer greater strains, and the ship soon become leakly and require to be re-fastened. Therefore the treenails should be made of the best materials, well seasoned in the open air, where they are exposed to all sorts of weather; which mode of seasoning produces treenails much stronger than those that are seasoned in the shade and kept quite dry. The treenails should be properly rounded, and of equal thichness from the point to within 1-4th of their length from the head, where they should begin to swell a little. By properly driving such a treenail, it will draw the plank close up to the timbers. On the bilge and other round parts of the ship, the treenails should all be wedged up to prevent the plank from starting from the timbers with the strain of caulking.
When the vessel is treenailed-off from the outside, you next saw off their heads close by the plank, and dress her quite fair from stem to stern, and also from the keel to the gunwale; then preare to caulk.
By squaring-off, is meant thightening of the treenails, and chinsing all the rents and shakes in the plank.
With respect to the tightening of the treenails, it answers two purposes, keeping the water from running up the pores or by the sides of the treenails, and the plank from drawing or starting off the timbers, and may be done in different ways. In many parts of the south of England, the treenails are made tight by caulking them crossways, which swells out the head of the treenail. (See first strake, Fig. 126, Plate VII.; those of a larger size in form of a triangle - see second strake; and the largest treenails in form of a square - see third strake.)
In the north of England, where an immense number of vessels are employed in the coal and coasting trade, their vessels are much exposed to striking the ground in going over bars in entering or leaving harbours, and in lying on the ground at times with heavy cargoes. The shipbuilder and masters of such vessels ought to know well what methods answer best to keep the treenails tight, and prevent the planks from drawing or starting over them. Accordingly, at these places, and several others, they tighten the treenails by driving three small tapering wedges or plugs into the head of each treenail. These plugs are made of well seasoned oak, and are about 1 1/2 inches long, and 3-8ths of an inch square at the head, and drawn to a sharp point; they are called punches.
That these should hold firmer than one large plug, is evident and consistent with theory, on account of their having a greater surface for the friction to act upon in proportion to their actual united contents, than one single plug which would swell the head of the treenail to the same degree. However, I have the following objection to this method of securing and tightening the heads of the treenails, viz. that in hot countries the punches in the treenails in the upper works of the vessel, when much exposed to the heat of the sun, are frequently observed to start out, and therefore not preferable to caulking the treenail-heads, as before mentioned.
The most general method used in Scotland is to drive one large plug or punch into the centre of each treenail, these being made of dry oak, about 2 1/2 inches long, and 5-8ths or 3-4ths of an inch square head. If the treenails are made of fir, the plugs are often of fir also; but either oak or fir plugs may be used for treenails. I have never heard any observations made to this last method of plugging.
When the treenails are all plugged, and the rents all caulked, the seams must be paid over very carefully; and one day's work of caulking being thus finished, the same process is gone through the next day, and so on until the vessel be all completely caulked.
N.B. - The seams in the way of such parts of the ship as are to be painted, are commonly paid over with rosin, which is cleaner than pitch; but pitch is preferable on all other accounts, as it is found that the rosin rots the oakum, and very soon decays itself.
If the outside plank is to be planed, it should be done immediately after the bottom is dressed; and after the ship is caulked, the seam edges and treenail heads will again require a touch over with the planes, to take off any parts of the seam edges, treenail heads, &c. which may have started a little by the strain of caulking.
Transcribed by Lars Bruzelius
Sjöhistoriska Samfundet | The Maritime History Virtual Archives | Shipbuilding | Fastenings.
Copyright © 1996 Lars Bruzelius.