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

Mr. T. B. Lightfoot, cont'd :

With regard to the machinery, Messrs. Earle had adopted the system introduced by the Authors, and they were glad to learn it had given such satisfaction. The hauling arrangement referred to by Mr. Taylor, had been considered by the Authors, both in connection with steam and hydraulic power; but they did not think it a desirable plan to adopt.

The work done in hauling a ship of 2,500 tons burden on to a slip would be about 170,000 foot-tons including friction : while to empty a graving-dock, capable of accommodating two vessels at a time, about 34,300 tons of water would have to be raised an average height of, say, 15 feet, equivalent to an expenditure of 515,000 foot-tons every time a vessel was admitted.

Sir W. G. Armstrong and Co. had only used chains for hauling up the cradle and load in the case of two small slips for dredgers and hopper barges, and such an apparatus was inapplicable for dealing with vessels weighing 2,500 tons. In any case the cost would fully equal, if not exceed, that of the appliances recommended in the Paper.

The next paper entitled 'On Slipways' [click to download complete paper] by Mr. William Boyd of Wallsend-on-Tyne and dated August 1881 [1048] presented to the Members of the Institution of Mechanical Engineers [178] provided an overview and comparison of 'Armstrong's System', 'Hayward Tyler and Co.’s System', 'Day Summers and Co.’s System', and 'Thompson’s System' of which the text is as follows: