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

The gradient is 1 in 19 ; and the machinery is sufficiently powerful to haul a vessel of 2,500 tons gross weight. the slipway could accommodate two vessels, each about 280 feet long, at one time.

In conclusion it may be mentioned that the Authors do not advocate the indiscriminate adoption of slipways in every case where it is desired to set up a ship-repairing establishment. They believe that the choice of plant, whether it is to be a graving dock or slipway, a floating or hydraulic-lift dock, must rest entirely with the engineer after a careful survey of the locality and a consideration of his resources. In very many situations, however, there can be no doubt that as regards first cost and facility in execution the slipway possesses advantages which should specially recommend it to capitalists, while from the shipowner's point of view the better ventilation around the vessel when it withdrawn from the water, the ample opportunity afforded for inspection, and the short time occupied in hauling up and launching, neither of which operations is necessarily dependent on the tide, except in very special situations, are all important features.

It is probably the combination of these advantages which has led to the financial success that the Authors believe has attended the working of every well-constructed and conveniently-placed slipway ; while on the other hand there is, unfortunately, little room for doubt that in many instances graving and other repairing docks have been a source of considerable loss ; though, as was pointed out by Mr. T. Stevenson, M. Inst. C.E., in his work on " The Design and Construction of Harbours, " they largely tend to raise the character of a port, and hence almost all harbours of importance have them.

In this Paper only such methods as are generally in use have been dealt with, and no attempt has been made to describe the obvious designs of greater or less utility which might be desirable under special circumstances. Such are the hauling up of a vessel broadside, as has been carried out at Bordeaux by Mr. Labat, and the provision of a traversing engine for shunting from the main ways, to enable several vessels to be slipped where length cannot be obtained to accomplish it in the usual manner. Reference should, however, be made to the combined floating dock and slips as first carried out in 1851 at Philadelphia and afterwards at Portsmouth, U.S.A., and at Cartagena and Pola.