23. State requirement for cooling & lubricating by water of stern bearing?

-Lignum vitae, synthetic rubber bearing uses water for lubricating and cooling. Seawater outside the ship or water pumped from engine room can be used for these purposes.

-These kinds of the bearings need enough capacity of water for lubricating and cooling. If lack of water, the bearings temperature increases then the bearings and shaft sleeve will be damaged. The best temperature for lignum vitae bearing is smaller than 50oC.

-For synthetic rubber bearing, when lack of water the friction coefficient of the bearing increases then bearing temperature will be fast increased and both shaft and bearing will be stuck to each other.

-The best water for lubricating and cooling is the pressured water pumped from the engine room after cleaned by a strainer. The flow of pressured water will clean sand and dirt from working surface of bearings when the ship sailing at shallow and dirty water area.

-The water lines must be provided with pressure gauges, sight glasses, thermometer to monitor the lubricating and cooling condition of the bearings. Water pressure £ 2.5 Kg/cm2, temperature ³ 20oC.

-Cooling and lubricating water for the bearings must be supplied before trying the main engine.