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

Mr. T. B. Lightfoot cont'd :

The hydraulic ram, worked on the Authors' system, only took twenty seconds to fleet instead of three minutes, and therefore the deductions on this head were incorrect ; and the same advantages as to speed in hauling up light vessels were gained in hydraulic apparatus as with wire rope by having the triple-powered arrangement shown in the diagrams.

Mr. John Thompson.

Mr. John Thompson said his remarks would be mainly directed to answering the objections which had been urged against the system of laying foundations under water for slipways without the use of cofferdams ; and by a few illustrations he hoped to show that this could be carried out with perfect efficiency and at moderate cost.

The various operations would be understood by reference to Fig.1.



When the portion of the site below low-water had been dredged out to the desired depth, the foundation was made by filling in broken stone of convenient size to near the level of the intended platform, upon which a layer of macadam was placed, bringing the foundation up to the required height.