Volume Two - The Era of Optimism, Investment & Development - The gridiron and slipway of the Penarth Shipbuilding & Ship Repairing Co. . . .

'Patent Slips are the contrivance of the late Mr. Thomas Morton of Leith, and consist of a carriage or cradle working on an inclined railway, falling at the rate of about 1 in 15 to 1 in 24, and extending from 300 feet beyond high water to several feet below the level of the low water. When this carriage is let down under the water the vessel is floated above the place, and the carriage drawn up till it catches the vessel forwards. When the ship is placed truly above the line of the carriage, powerful hauling gear, placed on top of the slip, which is worked by either steam or hydraulic power, is set in motion, and raises the truck and ship out of the water.

Messrs. Lightfoot and Thompson, who have made some improvements on slipways, state (Min. Pro. Inst. C. E. vol. lxxii.) that the expense of placing and hauling up a vessel weighing 2300 tons on the Penarth slipway may be taken as the wages of sixteen men for 1 hour, and three men for 2 hours. The Penarth slip is 876 feet in length, and the engine power is about 40 indicated H.P. Between the years 1879 and 1883 one hundred and thirty ships have been hauled up and repaired without the slightest accident, beyond the breakage of a few rollers at first starting.

. . . . Mr. Mitchell, shipbuilder, Newcastle-on-Tyne, says, "Speaking generally, I consider a slipway better than a dry-dock for all vessels up to 2400 tons gross register, which represents a screw-steamer about 310 feet long by 36 feet beam, and there is nothing to prevent much larger vessels being slipped ; but up to this time it has not been the custom to have stronger slips than corresponds with the above size."

The Gridiron is a simple framework of timber placed at a level sufficient to admit of vessels being floated above it during the flood-tide, and grounded upon it during the ebb, and when thus left high and dry the vessel's bottom can be examined to ascertain if it is necessary to take her into the graving dock, and trifling repairs can also be made.' [572]