BECOME SERIOUS BECAUSE OF THE FLEXIBILITY AND LOW 

 MASS OF THE DOMES. KARMAN VORTICES ALSO FORM WHEN 



a fluid flows around a sharp edged discontinuity 

 in the flow stream. such a phenomenon may occur 

 at the rear side of the triangular platform. 

 Should an analysis reveal that dynamic vibrations 

 could become serious, the application of "spoilers'' 



must be TAKEN INTO CONSIDERATION. SUCH SPOILERS 



change the aerodynamic flow pattern and reduce or 

 eliminate dynamic vibration. however, such devices 

 necessarily increase the drag on the structure. 

 Self-induced vibrations due to repetitive wave im- 

 pacts ON THE legs will NOT OCCUR FOR REASONS PRE" 

 V I OUSLY D I SCUSSED . 



ABRASION FROM WATER-BORNE SAND 



The amount and maximum particle sizes of sand sus- 

 pended IN water close to the sea bottom are functions 

 of the water velocity. Velocities close to the sea 

 bottom are induced by wave action and by tidal cur- 

 rents, the first be i ng osc i llatory with the period of 

 the wave and the second being transilatory in the 

 direction of the current. under the conditions found 



AT THE SITES AT GeORGE's BaNK AND NANTUCKET ShOALS, 

 EITHER TYPE OF SEA BOTTOM MOVEMENT HAS VELOCITIES 

 SUFFICIENT TO TRANSPORT SAND AND MAY CAUSE SERIOUS 

 ABRASIVE LOSSES TO SUBMERGED STRUCTURES. HENCE, ADE- 

 QUATE PROTECTION AGAINST SUCH ABRASION OR SAND 

 CUTTING MUST BE PROVIDED AT THESE TWO LOCATIONS. 



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