What is advantages of Foam on ships ?

In spite of its limitations, foam is quite effective in combating Class “B” and some Class “A” fires and has the following advantages:

1. Foam is a very effective smothering agent, and it provides cooling as a secondary effect.
2. Foam sets up a vapor barrier that prevents flammable vapors from rising. The surface of an exposed tank can be covered with foam to protect it from a fire in a neighboring tank.
3. Foam is of some use on Class “A” fires because of its water content. AFFF is especially effective, as are certain types of wet-water foam. Wet-water foam is made from detergents, and its water content quickly runs out and seeps into the burning material. It is not usually found aboard vessels; a more likely use is in protecting bulk storage in piers or warehouses.
4. Foam is effective in blanketing oil spills. However, if the oil is running, an attempt should be made to shut down a valve, if such action would stop the flow. If that is impossible, the flow should be dammed. Foam should be applied on the upstream side of the dam (to extinguish the fire) and on the downstream side (to place a protective cover over any oil that has seeped through).
5. Foam is the most effective extinguishing agent for fires involving large tanks of flammable liquids.
6. Foam can be made with fresh water or seawater, and hard or soft water.
7. Foam does not break down readily, and it extinguishes fire progressively when applied at an adequate rate.
8. Foam stays in place, covers and absorbs heat from materials that could cause re-ignition.
9. Foam uses water economically.
10. Foam concentrates are not heavy, and foam systems do not take up much space.