STRENGTH OF ANTIPITCHING FINS AND SHIP MOTIONS MEASURED ON USS COMPASS ISLAND (EAG 153).

• Main Authors: Becker,Louis A., Duffy,Donald J.
• Other Authors: DAVID TAYLOR MODEL BASIN WASHINGTON D C STRUCTURAL MECHANICS LAB
• Format: Text
• Language: English
• Published: 1959
• Subjects: Marine Engineering; (*SYSTEM TEST VESSELS; *FINS); PITCH(MOTION); MOTION; IMPACT SHOCK; ACCELERATION; SHIP HULLS; DAMPING; STABILIZATION SYSTEMS; CONTROL SURFACES; EAG 153 VESSEL; Compass Island; Psi
• Online Access: http://www.dtic.mil/docs/citations/AD0650591; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0650591

Strains and pressures were measured in the antipitching fins on USS COMPASS ISLAND (EAG 153) and were correlated with simultaneous measurements of sea state and ship motions. A maximum principal stress of 14,000 psi was obtained when the fins slammed in a State 6 head sea at a ship speed of 18.8 knots. As a result of this slam, the peak pressure measured on the fin was 72 psi. It is concluded that the strength of the fins is ample. The above condition was the most severe encountered and caused a maximum vertical acceleration at the bow of plus or minus 0.64 g, amidships acceleration of plus or minus 0.26 g,, and a maximum pitch angle of plus or minus 6 1/2 degrees. It is noted that both vertical and horizontal modes of vibration of the ship's hull were excited. As a secondary objective, the effectiveness of the fins in reducing ship motions is analyzed. While some reduction in pitch is indicated, it is believed that duplicate trials with and without fins are required to obtain conclusive results. (Author)