ENEMY OF SHIPS

Evening Star, Issue 20148, 12 April 1929, Page 7

ENEMY OF SHIPS

The United States army has declared war on the barnacle, a persistent enemy of ships (remarks fhe New York ‘ Times ’). After a series of experiments in the laboratories of the Chemical Warfare Service at Edgewood Arsenal. Maryland, the army Jins come forward with a paint which promises to pi event the accumulations of the crustaceans on ships’ bottoms. The fight has been going on for years. There is perhaps scarcely a ship sailing the seas ’he speed of which is not redwood or its fuel consumption inc; eased because its hull has become foul with shells. Barnacle is a name commonly used for all marine organisms which attach themselves to the bottoms of ships, although .strictly speaking the barnacle is but one of a number of these organisms. It is a conical-shaped shellfish, which attaches the base of its cone to the bottom of the ship. Other such organisms are the" hydroius, which look like grass, and hang from tho bottom; the tublaria, which form hard tubes along the surface, the ascidians, which cling together in large clusters; and the hryozoa, which form in round, flatpatches. These growth-; may accumulate to such an extent that they project several inches from the hull, but oven when they extend only a small fraction of an inch they materially impede the -ship’s progress The increased fuel consumption of a vessel rometimes amounts to 25 per cent , according to navy estimates, white of the fuel consumed on ail vessels sailing the high seas, it is said that about 75,000,000 dollars’ worth is "wasted each year, due to barnacles. Nor does this estimate include losses fiom reduced speed, consequent delay in reaching port, and the expense involving dry-docking the ships for the pm pose of cleaning off fhe buttons. Everv vessel lias to go to dry dock periodically now. Tho length of the dry-dock period depends upon the rapidity and extent of the growth of the marine organisms, and this depends largely upon the season and the latitude. In the tropics the growth is continuous, whereas in the temperate zones the fouling normally occurs only in the summer. The organisms abound principally near the shore, very few being found in the open seas, so that the fouling starts usually while vessels are in the harbour and at rest.

Extensive studies have been made to determine the nature of the surface for ships’ bottoms which would he unattractive as a place of Residence for these barnacles. Surfaces of various colours and smoothness, some as smooth as glass, have been tried, hub it has been found that the physical characteristic of the surface it a matter of indifference to 1 lie barnacle. It has been found, however, that barnacles are repelled fry certain toxic chemicals, and the incorporation of these chemicals in ship-bottom paints gives promise of providing a solution to the problem. A large number of these paints containing toxic chemicals have been prepared and tested by the Chemical Warfare Service, and then tried out by the navy. The paint that promises the solution is now being tried out by the destroyers, and contains as its toxic chemicals oxides of mere iiy and copper. The new paint is described as a “hot plastic, paint,” consisting essentially of r-oal tar and resin, in addition to the'toxic dvunhate- It is applied ;n a melted condition, and solidifies on cooling.