total weight of copper nails in one boat of these dimensions is about 37 to 38 lbs.

The writer has gathered a few particulars from information supplied to him by The Cartsburn Lifeboat Building Co., Greenock, which gives the approximate quantity of copper fastenings required in the 26-ft. lifeboat of standard dimensions. See Table XVII.

All reference to cost of production has been carefully avoided. The best method of arriving at an estimate should be based on the cubic capacity of the boat. Five weeks is a reasonable length of time required for the construction of a 26-ft. lifeboat of Class IA, with two journeymen and one apprentice, working on time rates and without overtime.

TABLE XVII.

APPROXIMATE NUMBER OF COPPER FASTENINGS. OPEN LIFEBOAT CLASS IA, CLINKER BUILD, 26·0′×8·0′×3·25′.

Carvel-built Boats.-An alternative method of planking a boat is by working the planks edge to edge, having their surfaces flush inside and out, as illustrated in Fig. 55. The majority of motor boats and high-class pulling boats are constructed on this principle or the double-skin method.

A "carvel" built boat is stronger than a boat constructed on the "clinker" principle. In the first place it is essential to use a greater number of moulds, and in the majority of cases, they have to be prepared from the faired sections on the scrieve board. They are built up as shown in Fig. 70, and as soon as the combinations of the frame of the boat are secured together and erected, the section moulds are placed in position and well secured by fore and aft ribbands placed on the upper edges.

It will be noticed that the moulds are made to the outside of the timbers. A suitable number of ribbands are fitted fore and aft from stem to sternpost, which gives the correct form of the boat at the inside surface of the planking.

The scantlings of the timbers can be reduced without detriment to the boat by a in., both moulded and sided, from the particulars given in Table XIV.

The timbers are then steamed and bent round to the inside of the fore and aft ribbands and temporarily secured to the latter. The outside surface of the timbers and the faying edges of the planks are coated with white-lead paint as the work progresses.

Special care must of necessity be exercised in fitting the plank edges in order to preserve a watertight joint. In fine work these are worked close together, but in heavier boats a slight chamfer

is given to allow for a thread of cotton to be caulked into the

seam.

The motor boat in course of construction shown in the photograph at Fig. 142 was timbered on this principle.

The planks are secured to the timbers by copper nails clenched over rooves, one row at each edge, care being taken that when the nails are driven into the timbers the direction is such that it will have the tendency to close the seam. The process of clenching the fastenings can be completed as each plank is worked.

The usual precautions which must be observed in planking a "clinker" built boat, and already explained in some detail, apply to a boat built on the "carvel" principle. With the former the timbers are bent when the boat is planked, and with the latter they are usually bent before the planks are worked. The practice varies in different districts, but the writer is inclined to think that a fairer boat is produced by the method described.

As the planks are secured to the timbers, so the ribbands are

removed from the moulds. The rubbers are usually fitted direct to the timber as shown in Fig. 55.

Double Skin Boats. The highest class of motor or pulling boats is constructed with two skins, having a waterproof fabric between. Provided the material is well seasoned and of suitable quality, there is no reason why the lifeboats should not last the life of the vessel.

There are at least two methods of working the planking, but other methods will also be referred to when dealing with the construction of pontoon lifeboats and open lifeboats of Class IIA.

The stronger boat of the two, when built on the double skin principle, has the inside and outside strakes of planking running

Methods of working the planking of double-skin boats.

at 45° with the keel, but each in the opposite direction, so that the two skins cross each other at right angles. This method is illustrated in Fig. 71.

The second method, shown in Fig. 72, consists of an inner skin with strakes of planking running aft at 45° to the keel, and an outer skin with strakes running fore and aft as in a carvel built boat.

66

In both cases waterproof linen is worked between the two

skins.

Practice varies in different districts throughout the United Kingdom. The writer will therefore confine himself to a brief description of the method of planking a double-skin boat, constructed on the diagonal principle, which has come under his immediate

notice in the yards of Messrs. Dickie and Sons, Tarbert, Loch Fyne, and Messrs. Caird and Co., Greenock (now Messrs. Harland and Wolff, Ltd.).

Boats with small dimensions (up to 22 or 23 ft. in length) can be constructed on the "diagonal" principle, having moulds built up as shown in Fig. 70, a description of which has already been given when dealing with "carvel" built boats. When it comes to boats of larger dimensions, the moulds are made of more substantial material, and not of the usual "mould stuff." They are made to the inside of the timbers, and carefully checked with the lines on the floor or scrieve board.

The ram or frame, i.e. the stem, keel, sternpost, with hog, deadwoods, etc., having been erected in position and made to plumb the keel-board, with the stem and sternpost outwinding, the whole is rigidly secured to prevent any movement during the early stages of construction.

The moulds are then placed in position, plumbed, and set up in conformity with the line of keel, stem, and sternpost. The headboard is fixed and secured by shores from the overhead structure. The moulds, therefore, practically become fixtures, and are not removed until the boat is planked, timbered, and gunwales secured. Reference should be made to Fig. 69 for an illustration of the moulds referred to.

Now comes the feature of construction where practice differs according to the tastes of various builders, but the following is considered to be the simplest and best arrangement of planking.

The moulds being made to the inside of the timbers and fixed in position, good stout ribbands are worked fore and aft and let into and secured to the moulds, so that the outside surface of the ribbands are flush with the edge of the moulds. The necessity for stout moulds is, therefore, obvious.

We now have the longitudinal shape of the boat given by the ribbands.

It is usually arranged that the deadwoods and aprons are left slightly larger than specified, to allow for their being trimmed fair with the lines of the boat.

The timbers are spaced about 9 in. apart, and the scantlings equal to those shown in Table XIV. The wider spacing is permissible owing to the additional strength received from the diagonal planking. They are now steamed, fixed to the hog, and clamped to the ribbands until the gunwales are worked. The latter are sided and moulded to meet the specification requirements and placed in position.

The gunwales may be solid or of the "box" type; if the former is fitted, the timbers and inner skin of planking are usually checked into the gunwale, with a good capping piece covering the gunwale and the upper edges of the outside strakes of planking, as shown in Fig. 79 c.

The planks are now prepared and steamed, while an abundant number of small shores are placed at the disposal of the boatbuilder and within easy reach.

The inner skin is first dealt with; these planks are worked diagonally at an angle of 45° from the line of keel. The upper ends lie aft, they are worked in one length from keel to gunwale. The inside surface is planed before working so that a slight touch up with a " flat scrape" is all that is necessary to obtain a good inside surface on the completion of the boat.

As the planks are worked they are secured to the hog, gunwales, deadwoods, and aprons, with 12-in. spikes, sufficient to keep the planks in position, until the outer skin is fitted.

The inner skin having been completed, a slight chintz of boatcotton is worked in each seam in way of the hog, aprons, and deadwoods, this precaution being considered essential for watertightness.

The outer surface of inner skin is then coated with good whitelead paint and waterproof linen stretched thereon.

The operation of working the outer skin is commenced and performed in the same manner as the inner skin, except that the planks lie forward.

The short shores referred to previously are used for keeping the planks in their correct position before fastening.

The two skins are fastened together with copper nails clenched over rooves, the disposition of the latter being ascertained before the planking is commenced. The securities are completed as the outer skin is worked, being lined off by the person responsible for the boat. The outer skin is fastened to the hog, apron, stem, sternpost, and deadwoods with spikes or brass screws, and to the gunwale and hog-piece by clenched nails. Figs. 73 and 74 show the general arrangement of securities in way of the keel and apron of a boat constructed on the "diagonal" principle.

From four to six floors cut from material grown to shape are usually fitted in the large pulling boats.

Throughout the operation of working the two skins particular care should be exercised to avoid "puffing" or "holidays," i.e. there must be a perfect fit between the two faying surfaces.