MARINE engineering practice, similarly to many other branches of engineering, no longer follows precedent. Not long ago the recognized propelling machinery for the coasting vessel was a steam engine with boiler. To-day the heavy-oil engine is often fitted. An excellent example is the motor vessel Castle Combe, a cargo vessel of 454 tons gross, 155 feet long. A view of her engine-room is shown above. There are no boiler-room or coal bunkers and the space thus set free gives more room for cargo and provides much better accommodation for officers and crew than is found in a steamer.
Clean, roomy and well-lighted, the engine-room is a great contrast to the crowded, hot engine-room and stokehold of the old-fashioned type of coaster. In the centre of the engine-room is the main propelling engine, seen to the right of the illustration. The engine runs on heavy oil and is a Ruston seven-cylinder internal-combustion engine developing 500 shaft horse-power at its normal speed of 430 revolutions a minute. This speed being much higher than is suitable for driving the propeller, the engine is arranged to drive this through a reducing gear so designed that the propeller runs at 172 revolutions a minute, which gives a speed of just over 10 knots. The object of installing a high-speed engine is to get more power in less space.
The cylindrical tank seen at the far end of the engine-room is a boiler through which the exhaust gases from the engine are passed on their way to the air. This arrangement gives a supply of hot water throughout the vessel for cabin radiators and the like. In port, when the main engine is not running, the water is heated by electric-immersion heaters.
The smaller engine seen to the left is a Ruston four-cylinder oil engine developing 30 horse-power. It drives an electric generator providing current to the electrically driven capstan and winches on deck; it drives also a bilge pump, a ballast pump, a stand-by lubricating oil pump and an air compressor which supplies compressed air for starting the main engines. The switchboard is seen behind this engine.
The main engine drives, in addition to the propeller, two bilge pumps, a circulating pump for the cylinder cooling water, a dynamo for lighting the vessel, a duplicate starting air-compressor and two forced-lubrication pumps. The duplication of some of the services is provided so that they can be run by the auxiliary engine when the main engine is not working. Electrically driven deck machinery, electric lighting and hot-water radiators are in great contrast to the old leaky steam winches, the dim, smoky oil lamps and the ineffective stoves of the old-type ships; but these modern appliances are not the only modern things in the Castle Combe. The galley has an oil-fired cooking range and there are other conveniences. The hull, too, is modern in that electric welding has been used to a large extent in place of the old-time riveting.
