SPEEDING-UP SHIPS

Hokitika Guardian, 25 July 1931, Page 6

SPEEDING-UP SHIPS

TESTS WITH NEW INVENTION. SIMPLE BUT EFFECTIVE. A simple device to speed up ships is to be tried for the first time on a Thames tug (says the London “Sunday Chronicle”). The device, it is stated, has already demonstrated its ability to increase speed by 15 per cent, in one case, and it is guaranteed to do so by at least 5 per cent. “If it were fitted to the Mauretania” said the inventor, Mr J. H. Pescod, formerly chief draughtsman of Messrs Swan, Hunter and Richardson, the Tyne shipbuilders, “I am confident she would beat the Bremen.” The idea is essentially a shelf fitted over the propellor so as to deflect the flow of water “squarely” in to the blade of the screw. Although Mr Pescod has only been fitting his device for a few months, he quotes an impressive number of river and sea-going craft, varying between 14 and 1580 tons, which have recorded increases of speed ranging from 5 per cent, to 15 per cent.

Tried Out on Model

Mr Pescod states that his simple, invention was born of five years’ work. It was first suggested by the flat-sliap-pd sterns of destroyers, and Mr Pescod tried it with a model on a lake in Tynemouth Park. The crowd watching the experiment with the 6ft “tramp” had. no conception of the issues at stake or of the anxiety with which .the times of her performances were measured.

First she steamed without the shelf, or “fin”; then this was added, and an increase of speed of a few inches per second was recorded. This was, relative to her size, no less than 10 per cent., meaning a 30 per cent. increase to power and corresponding economy.

Then came the task oi* arresting the attention of shipowners. Mr Pescod made a glass tank 6ft long, in which he floated a model. A small line to the stern kept the ship stationery when the engines revolved, while ink injected by a foundtain-pen filler made visible the eddies of the screw and the flow of water under the stepi ot the ship. Although impressed, shipowners seemed reluctant to fit the fin. The first order secured was from the owners of a steamship of 275 tons, but then only on a “no cure—to pay” basis. At first the device was only a partial success, yielding a 2) per cent. Instead of a 5 per cent, increase of speed. This small increase was, however, sufficient to cause the ship name to be removed, from the sale list, as it made all the difference between catching and, missing;jthe tide. , _

Firm Supplies a Tug

The first owners to give practical assistance to Mi- Pescod were a Dutch firm, who supplied a tug. men, and material for experiments. These tests produced a. 4 per cent increase of speed.

Alter varying successes, luck contributed An idea of considerable importance to the device. Hitherto tbe “fin” had been flat. The peculiar lines of a certiaip ship to which it was fitted rendered it necessary, however, to curve downwards the forward ends of the fin, like the handle of a tenspon. To the inventor’s surprise this downward curve gave further increase in efficiency.. The curve of the fin is now made to conform to the lines of the ship. In addition to increase in speed, it is claimed that steering is improved, propellor racing reduced, and better acceleration derived when going astern. The ship to which the fin is now being fitted is the H.V. Liddo. She is 92ft. long and carries 150 tons of oil. Her present speed of 7*J knots is insufficient in bad weather in the North, Sea.

“The extra half knot or so will make all the difference,” said Mr Pescod, “but I shan’t he happy until I see my fin fitted to some of the big, fast ships.”