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

Mr. John Thompson cont'd :

Notwithstanding the clear explanation of Mr. Summers, Mr. Thompson still saw great difficulty in providing in the gearing sufficient strength to carry the strain upon the rope. It would require a very large drum, and that necessitated so large a spur-wheel and so large a pitch that he thought its use would be attended with great risk.

Correspondence.

Mr. G. B. Godfrey.

Mr. G. B. Godfrey only last year had completed, for Earle’s Shipbuilding and Engineering Company, Limited, at Hull, the largest slipway that had yet been constructed. He referred to its bearing power for taking dead weight, and the hauling power of the engines. The length of the slipway was about the same as that described by the Authors, namely, 860 feet, and having an inclination of 1 in 25.

For the foundations he could not agree with the Authors, that mere “ surface dressing ” was sufficient, excepting where the ground was rock or other hard material. He thought on all softer ground, piling for the whole length was a superior mode of construction, and less subject to settlement, and consequently less costly in maintenance than ordinary excavation and “ filling in with suitable material.”

With piling, and also the method of construction described by the Authors, the whole structure was so bound together, that any settlement or lateral movement was not possible ; but, without piling, there must always be a tendency to unequal settlement of the ways, which, he thought, would not be so easily wedged up as the Authors suggested ; and, if at any time overlooked, might cause a severe strain to the ship by the displacement of the cradle when being hauled up. Without piling there was also a tendency to a lateral movement, which might also cause a straining to the ship should the sideways move out of line as the vessel was leaving the water, and her full weight and bearing settling on the cradle.