Volume Three - The Pontoon Era - The new pontoon commissioning and its early use . . .

In the trials which took place on the 10th March 1910 when the S.S. “Ethlhilda” was lifted the Dock was raised to a mean freeboard of 7” in a net time of 50 min., the corresponding figures being as follows:-

Comparing, however, the two sets of figures, it will be seen that in the former the mean rate of output is 6160 / 75 = 82.13 tons per minute, while in the latter the mean rate of output is 4100 / 50 = 82 tons per minute. That is to say that the pump discharged at just under the rate necessary to raise the ship in the contract time. Comparing, however, the rate of doing work, it is necessary that the engines have sufficient horsepower to do 125,690 ft-tons of work in 75 minutes, or at the rate of 124,690 / 75 = 1,676 ft-tons per minute, whereas they actually did 60,860 ft-tons in 50 minutes, or 60,860 / 50 = 1,217 ft-tons per minute, or 27 per cent. less than required. The test cannot, therefore, be regarded as satisfactory."

How, if or when the performance of the pumps was upgraded to meet contract is not known but the report is an interesting view of the operational aspects of the pontoon.