Fig. 62.—Sir Robert Seppings' system of construction.
Secondly, the beams were connected with the sides of the ship by means of thick longitudinal timbers below the knees running fore and aft, called shelf-pieces, a, a (Fig. [63]), and similar pieces above the beams, b, b (Fig. [63]), called waterways. These not only added to the longitudinal strength of the ship, but formed also very convenient features in the connection between the deck-beams and the ship's sides.
Fig. 63.—Sir Robert Seppings' system of construction.
Thirdly, a trussed frame was laid on the inside of the transverse frames in the hold of the ship. This frame consisted of diagonal riders making an angle of about 45° with the vertical, together with trusses crossing them, and longitudinal pieces, as shown in Fig. [62]. This trussed frame was firmly bolted through the transverse frames and the planking of the ship.
Fourthly, it was proposed to lay the decks diagonally; but this system does not appear to have ever come into general use.
It should here be mentioned that the use of shelf-pieces and thick waterways in connection with the ends of the beams was first adopted by the French in very small vessels; also the system of fillings between the frames was an extension of a method which had been in use for some time, for it was customary to fill in the spaces as far as the heads of the floors, in order to strengthen the ship's bottom against the shocks and strains due to grounding.