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

Mr. G. B. Godfrey cont'd :

In constructing the slipway for Earle’s Company, whole timber piles, cross-sleepers, and longitudinal bearers 13 inches square were used throughout. In the centreway two rows of piles were driven 18 inches apart from centre to centre transversely, and 3 feet from centre to centre longitudinally. For the sideways, single piles were driven 6 feet from centre to centre, these coming opposite every second row of piles in the centreway, thus giving one pile for each lineal foot of slipway, or a supporting power of 10 or 12 tons per lineal foot.

A sleeper 30 feet long was placed transversely on the four piles, and one 6 feet long on the two intermediate piles. Upon these sleepers were fixed the longitudinal timbers, or rail bearers, securely fastened with oak trenails. The centre timbers were 4 feet 6 inches wide to take a plate of the same dimensions. The ground for 4 feet below the cross-sleepers was excavated, and filled in with rough chalk for a width of 15 feet on both sides of the slipway; the whole was planked over with 3-inch red-wood deals.

A few remarks as to the mode of construction and the method of piling might be of interest. A cofferdam could not be thought of, the situation being exposed, and the sides of the slipway would have required closing by an embankment before one could have been constructed. This would have been too costly. The width of the slipway being 30 feet, a traveller 35 feet wide was constructed to span it transversely ; longitudinal timbers were laid on the prepared ground, having ordinary rails fixed upon them.

The diameter of the traveller wheels was made to suit the inclination of the slipway. Upon this traveller was placed one of Sisson and White’s steam pile-drivers, with 40-feet leaders, and a ram weighing 21 cwt.

The formation was partly made ground on the foreshore, and, to obtain the requisite inclination, an average of 10 feet of excavation had to be taken out at low water and carried to the upper portion of the slip, to form the necessary embankment for the slipway, and also for roadways leading from the shipyard.