Navies of the world

by Edward W. Very

It is considered that all these points are generally understood, and they are simply referred to on account of the necessity of bearing them in mind in following the developments.

Diagonal Construction.

This system of construction is found only in the English royal yachts and in their heavy wooden steam and sailing launches, but it is the opinion of an eminent English naval architect that had it not been for the very general introduction of iron in ship-building it would probably have taken precedence over the ordinary wooden construction. Its only objectionable feature is its expensiveness, while it is much superior in point of lightness and structural strength. Whilst in the ordinary wooden construction the weight of hull ranges between 46 and 54 per cent of the displacement, it is reduced in the diagonal system to between 32 and 40 per cent.

Diagonal Construction.

In this system the keel, keelsons, stern and stern posts, and floor-timbers are similar to the ordinary construction. The heavy frames, however, stop with the floor-timbers, and there is no diagonal iron framework. The outer and inner planking of the ship are the same as in the old construction except that the thick strakes of outer planking forming the wales are done away with, retaining only the heavy garboard-strakes. In place of the futtocks and top-timbers of the old construction a double course of diagonal planking is introduced. That part of the inner planking which covers the floor-timbers is of the ordinary thickness, whilst beyond the timber-heads the planking is increased in thickness to give a smooth turn to the bilge ceiling. These four or five strakes are rabbeted into each other and into the timber-heads. The clamps and water-ways are as in the old type. In order to give transverse strength to this system, the knees are constructed in a peculiar manner. The lower leg of the orlop-deck hanging knee is carried down beyond the head of the floor-timber. Every other knee is forked, giving a housing to the beam-end, the two legs following the curve of the clamps and water-ways and rising with a spread of half the height between decks and beyond the foot of the hanging knee over it.

This system of construction has found great favor in England in the construction of yachts, and it has been very successfully applied to sailing merchant-ships and steamers.

Composite Construction.

Jordan’s Composite Construction.