Marine life, such as algae, barnacles, and mussels, has been the scourge of shipbuilders for centuries. Marine growth also has become a serious problem for offshore operators and platform designers today. While ir has always been advantageous to keep marine growth off of ship hulls to maintain speed, save fuel, and keep ships working instead of in drydock, it is vitally important to prevent biofouling on offshore platorms for different reasons.

In many areas of the world, marine life - such as barnacles, mussels and algae - doesn't build up much more than an inch or two. However, in many areas, such as offshore California and the North Sea (anywhere waters are relatively cold and thus hold more nutrients), biofouling can build up to as much as 36" to the side. It becomes dangerous, since weight increases the strength requirements of the platform.

Depending upon the type of growth, biofoulants can weigh up to 150 pounds per cubic foot. It becomes dangerous, since it creates added area for wave loading, and drastically reduces the fatigue life of a platform.

Also, the danger of platform overturn is increased. When biofouling becomes excessive... reaches about 6" or more... platforms must be constructed much stronger than normally would be necessary, or the growth must be removed regularly.

Traditionally, in the petroleum industry, platform designers have taken two approaches to combat the severe problem. First, some have used much thicker metal and driven pilings deeper into the ocean floor.

They design as if the buildup on platform members and conductors would present a solid wall to wave action. This approach is very expensive, and on deeper platforms can cause a weight problem that makes transportation and installation difficult.

A second approach is to plan for periodic removal of the marine growth, and to design and budget accordingly. Waterblasting biofoulants from 48 conductors off California costs about $75,ooo per occurrence. And, the growth comes back twice as fast as it originally formed, so subsequent removals must be more frequent.