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

that in many situations, with regard to first cost and facility in execution, the slipway possessed advantages which should specially recommend it to capitalists. That modest claim almost disarmed criticism, for it was undeniable that in many places the establishment of slipways for the repair of vessels of moderate size was a good and cheap substitute for dry or floating docks.

When, however, it was asserted that “Since then the improvements introduced have been entirely in the details of the apparatus, which, from being at first merely required to deal with the light wooden ships in use at the commencement of the present century, is now constructed for speedily withdrawing is from the water the largest existing iron vessels,” one naturally inquired where such slipways were to be found, and under what circumstances they had been built ; for although slipways for small vessels were preferable as a rule to other modes of dealing with vessels requiring repair ; it by no means followed that the same remark applied to vessels of very large tonnage. It was well known that at the present day there was a perfect mania for building large ships, and that merchant vessels from 3,000 to 5,000 tons were numerous everywhere.

Perhaps the Authors could state where slipways were found capable of accommodating vessels of that displacement. The only illustration given by them of a modern slipway was shown in Figs.1 and 2 for vessels up to 300 feet in length and 2,500 tons gross tonnage, and to that example he would confine his remarks.

It was obvious that in rivers, in tide-less seas, and where the range of tide was very inconsiderable, such as the Mediterranean, the length of a slipway under water must be very great to accommodate the long oceangoing steamers of the present day.

With a slope of 1in 19 (which, it was said, was a suitable one for a large slipway) the submerged slipway in a tideless sea or a river at very low water must have a length, if curved ways were not used, of at least nineteen times the draught of the ship to be raised, merely to reach her stem ; and, in spite of the telescopic arrangement that had been so well described, the slip would require to be further extended to at least one-half of the length of the vessel.