Volume Ten - Pre-Victorian to the present day - even more aspects - The Patent for the Penarth Slipway - 1881 . . .

◊ Slipways for Repairing Ships - Plate 6 - Figs. 8 to 11.

A new method of relieving (Thompson and Cooper's patent) has just been brought out by one of the Authors, and Mr. George Cooper, the late manager of the Penarth Slipway Company, Limited. It is shown in Plate 6, Figs. 8 to 11, and may thus be described : -

Instead of employing one cradle, two are used, constructed in such a manner that a vessel having been hauled up to a certain point upon the main cradle, can be transferred to the auxiliary one, the main cradle being thereby set free to receive a second vessel. With this object in view the main rails of the slipway are constructed in the ordinary manner, and at the ordinary inclination, but of such additional length as may be required for the working of the auxiliary cradle. Alongside the upper portion of the main rails, and parallel with them, is placed a second set of ways upon which the auxiliary cradle travels.

The slope of these rails is greater than that of the main ways, in order that when a vessel has been hauled up until it is over the auxiliary cradle, and the new bilge-blocks have been fitted, the heaving up of the two cradles simultaneously may cause the vessel to be gradually lifted by the auxiliary cradle from the increased inclination of its rails, so leaving the main cradle free to be lowered down the ways for receiving the second vessel, after the transverse arms have been swung round into the longitudinal position.

When the ship is to launched, the main cradle, with its arms swung round and resting on the side ribs, is hauled up under the vessel, the arms are then put into position and the bilge-blocks run in, and the main auxiliary cradles simultaneously lowered down the ways. The greater slope of the rails of the auxiliary cradle causes the vessel gradually to approach and seat itself on the resting blocks of the main cradle, and the bilge-blocks on the auxiliary cradle being removed, the vessel, now supported entirely by the main cradle, is run down the ways and launched.