fixed platforms are not available at this time, but it is obvious 

 that a well-designed structure of the smaller class of tower re- 

 quires much less expensive maintenance than the usual oceanog- 

 raphic vessel, although this may depend in certain instances upon 

 the size of both tower and vessel. 



A final advantage is that fixed platforms are quieter, acous- 

 tically and electrically, than ships. 



The main disadvantage in fixed platforms is a limitation in 

 geographical coverage. The nnovement from one area to another, 

 as with an oceangoing vessel, is not possible. Range, however, 

 can be increased somewhat through the use of booms or floats, 

 although the latter cannot qualify as a stable platform. 



Another disadvantage with the fixed platform is the limited 

 depth at which they can be safely constructed. This is generally 

 considered to be about 200 feet. Such a depth restricts the use- 

 fulness of towers to what is sometimes called "shallow-water" 

 oceanography. A somewhat lesser disadvantage is the creation 

 of an unnatural environment, particularly at the bottom. However, 

 reflection and refraction of the waves in the substructure, and 

 their effects on biological population, may be minimized by 

 proper structural design. 



Towers and other fixed platforms cannot run for shelter 

 when a storm arises, and, consequently, they are subject to 

 damage by high winds and waves. A hurricane destroyed the 

 first fixed platform at Caplan, Texas, as well as the first Panama 

 City oceanographic tower. Fire devastated the Magnolia Petro- 

 leum Company platform off Louisiana, a hazard of interest to 

 oceanographers since some towers are used jointly by oii com- 

 panies and oceanographic research groups. At Woods Hole, the 

 windmill structure in Buzzards Bay was toppled during a hurri- 

 cane. The recent loss of a Texas Tower in a hurricane was 

 widely publicized. Fixed, open-sea platforms frequently present 

 boarding and debarking hazards in bad weather. 



The most common type of fixed platforms employed in 

 oceanography are piers. These are especially useful for in- 

 vestigating sea boundaries that extend across the surf, and the 

 resulting wave action and beach erosion. 



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