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

Mr. R. H. Tweddell.

Mr. R. H. Tweddell, considered that the Paper had been brought before the Institution at a very appropriate time. The building of new ships was proceeding at a rate hitherto unexampled ; it was, therefore, evident that ready and economical means of repairing and maintaining these vessels must be provided in a similar ratio. When such repairs required that the vessel be left high and dry, it was an important matter to reduce the cost of so heavy an undertaking.

He should like to ask what was the relative cost of pumping out a graving dock, in order to admit a vessel, and of drawing up a vessel on to a slipway, assuming the repairing capacities per annum to be equal ; also, the relative cost of the mechanical appliances in each case.

In the graving-dock there would be the pumping apparatus as against the hauling apparatus in the other. The cost of cradles might be put against that of gates or caisson, leaving the cost of masonry foundations, &c., out of the question, as these varied greatly in different cases.

While a slipway undoubtedly presented some advantages in allowing easy and early access for painting and drying, he should imagine that a graving-dock would be the best for such extensive repairs as lifting out boilers or engines, since sheer-legs could more easily command the vessel in this case, although, of course, sheer-legs were now very often conveniently placed near slip-ways.

He should like, also, to ask whether there was any difference, as a rule, in the rate per ton for repairing a vessel on a slipway or in a graving-dock. This question would arise in cases where the owners of the slipway or dock did not undertake the repairs.

In comparing the relative merits of slipways and graving-docks, it had been asked if, in the case of a certain slipway, the dividends were not due to the profits arising from the repairs done on the slipway, since a slipway was only to enable repairs to be effected.