Hedderwick: Marine Architecture (1830)




Coppering.-- When a vessel is to be copper-sheathed, the bottom should be dressed very smooth, and all the projecting parts neatly rounded off. In several parts of Britain, it is the custom to plane the bottom, which takes off all the protuberances left by the roundness of the adze. This is an excellent plan, and makes the copper lie close to the plank, and have a very smooth surface.

Before commencing with the coppering, the ship should be all properly caulked, the seams paid over with pitch, and also all the rough pitch scraped off the edges of the seams, which are then to be filled up level with the surface of the plank. This is sometimes done by driving a thread of oakum in the mouth of the seam, but more frequently by nailing in a thread of spun yarn. After this, the bottom must be paid over with tar boiled with a little pitch to a gluey consistency, considerably softer than what is commonly used for paying the seams. The paper must now be prepared, by being dipt in the warm tar and pitch, and left to dry for a few days before it is used. The copper must be pierced before it is brought to the ship, except what sheets may be required for the upper parts and ends of the vessel, which have to be cut suitable to the place where they are to be nailed on, and fillings up where square-sheets are not wanted.

The copper sheets are commonly about 4 feet long, and 12 or 14 inches in breadth, covering each about 4 feet of surface of the ship's bottom when nailed on. The thickness of the copper is denominated by the weight per square foot; the lightest used is 16 ounces per square foot, and running up to about 28, and sometimes to 32 ounces per square foot, which is the heaviest. The size for merchant vessels is commonly 24-ounce copper for the luff of the bow and bilges, and 18 or 20 ounces for the rest of the bottom, except a breadth or two along about the load-water mark at midships (which is apt to be rubbed by boats or fenders) which is put on of 24 or 28 ounce.

Sometimes the whole of the copper on the fore-body of the ship is 4 or 6 ounces heavier than on the after-body, it being found to wear faster on the former than the latter part of the ship, by the reaction of the fluid when sailing. The piercing of the copper is commonly done by hand, with a short small-pointed punch made to the exact size of the nails, with a shoulder or stop to prevent it going too far through.

The place of the nails on the sheet is marked off with a chalk line, after this manner: Strike a line all round the edges of the sheet, 5-8ths or 3-4ths of an inch within. Between the side-lines, divide the breadth into three or four equal parts; strike the chalk-line along the sheet on these divisions, thus making a line for two or three row of nails along the middle of the sheet. It is next divided the other way, by setting, from the line across the end, distances equal to what the lines along the sheet are apart; then strike lines across the sheet at these equal distances, which will divide it into squares of three or four inches, at the intersections of which the holes for the nails are to be punched; and on the line at the edge, and one end of the sheet, an additional hole between every cross-line, making the distances between them 1½ inch, which is the farthest they should be apart. All the middle holes are pierced one edge and one end, the other edge and end being pierced after the sheet is put on. This first sheet is called the pattern-sheet, all the others being done in the same manner.

Having the pattern-sheet thus lined out, lay a sheet upon a hard block of wood having an even smooth surface; place the pattern-sheet exactly over it, fasten them both to the block with two or three nails, then punch the lower sheet through the pattern; and thus you may continue punching, using the pattern-sheet for a considerable time until the holes in it appear to widen, when it will be necessary to change it, and use another for that purpose.

It must also be observed, that the copper punched through this pattern-sheet is only for one side of the vessel; and that required for the other side must have the end-holes in the opposite end of the sheets.

The paper and copper being thus prepared, the paper is put upon the vessel's bottom with small tacks or scupper nails. In commencing with the copper, it makes the most regular work to begin at the upper part of the bottom amidships, and work from that towards both ends of the ship, carrying the edge as fair as possible, and giving the after end of every sheet one inch of overlap over the fore end of the other, at the same time taking particular care that each sheet lie quite flat to the plank. In nailing, always begin in the middle of the sheet, and complete the two or three middle rows, beating the copper completely up before you commence nailing the edges, otherwise it will bag off between the nails.

When you approach towards the ends of the vessel, the sheets will begin to rise at their fore and after ends; therefore their upper edges must be gored or cut off to the proper height till such time as they are diminished to 1½ inch in breadth. When this first strake is completed, begin with the next under, placing the end of the beginning sheet right under the middle of the one above, and its upper edge, so as to cover one inch of the lower edge of the sheets above. When a number of sheets are tacked on, begin and nail them first in the middle; work them close up to the plank; punch the lower edge of the sheets above through the holes in the upper edge of the sheet below, and the fore end of the sheet abaft each; after they are all properly nailed, they must be beat perfectly smooth with a mallet. When you come to the stem, take care to ply the copper neatly into the hoods, not regarding how the edges of the sheets may appear to run, provided they are close fitted to the plank. When they are all nailed to the sides of the stem, its fore part, and two or three inches round each side, must be coverted with sheet-lead of from 1-4th to 3-8ths of an inch thick, and properly fastened with copper nails a little stouter than those used for nailing the copper. Supposing several strakes got round, continue to work downwards till you come to the bilge, and then work from the keel upwards; fix the sheets first to the sides of the keel with a few nails, to keep them to their proper place; then work them neatly into the corner of the rabbet, and drive the nails close to it; ply the sheets close to the keel and bottom plank or garboard-strake; turn up the edges of the copper or lead which is under the keel, and nail it over the lower edge of the copper on the side of keel; continue to work outwards towards the bilge, making the outer or upper edges overlap the under edges of the next succeeding strake right fore-and-aft. When you come near to the bilge-planks, where the size of the copper is altered, fill up the goring or narrow ends forward with the strong copper as well as that on the bilge amidships; but the gorings on the after-runs is the same size of copper as on the other parts of the bottom. In coppering the stern-post and rudder, if sheet copper is not put under the straps of the braces and pintles, you must be very careful to put it neatly round them, and set close to all their edges with a caulking-iron; the copper must also be nailed quite close to the back of the stern-post, otherwise it will soon be chafed off; also be very particular how you fit the copper into the end of the keel. The bottom sheet on it and the lower end of the rudder should be very strong copper. On the other parts of the rudder, the copper may be of the common thickness.

Peter Hedderwick: A Treatise on Marine Architecture, containing the theory and practice of shipbuilding, with rules for the proportions of masts, rigging, weight of anchors, &c including Practical Geometry and the Principles of Mechanics; observations on the Strength of Materials, Hydrostatics, &c. with many valuable tables calculated for the use of shipwrights and seamen; also the proportions, scantlings, construction, and propelling power of steam-ships. Illustrated with twenty large plates, containing plans and draughts of merchant-vessels from fifty to five hundred tons, with mast and rigging plans; plans and sections of a steam-boat of eighty-horse power; and eight quarto plates of diagrams, &c., by Peter Hedderwick.
Printed for the Author, Edinburgh, 1830. pp 329-331.

Transcribed by Lars Bruzelius

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© Copyright 1997 Lars Bruzelius.