Seakeeping

 

Seakeeping performance was one of the most important design parameters for AGOR 26 since the main point of the program is to expand the oceanographic fleet’s ability to perform research in higher sea states.  The design goal for seakeeping was full operability in upper sea state 6 (SS6) in all headings.  Full operability was defined as meeting the following motion limits: 

             Pitch:                            3 degrees

            Roll:                              5 degrees

            Heave Acceleration:       0.4 Gs

            Lateral Acceleration:      0.2 Gs

 The seakeeping analysis was computer generated based on model test damping factors for similar hull forms and the MIT WAMIT computer code.  At the conclusion of Phase I, the ship meets all motion criteria with the exception of the 3 degree pitch requirement at zero speed.  The pitch requirement is met in lower SS6 but not in upper SS6, particularly in following seas.  The computer calculated values were 3.41 degrees of pitch at best heading and 4.9 degrees of pitch at worst heading in upper SS6.  Further review will be performed in Phase II to determine if more improvement can be achieved.  Computer generated seakeeping predictions are shown in the following figures:

Pitch Response                                               Roll Response

wpe5.gif (9930 bytes)           wpe7.gif (8199 bytes)

Heave Acceleration - G's                                Heave Response

wpe8.gif (8442 bytes)           wpe9.gif (7139 bytes)

Sway Acceleration at CG

wpeA.gif (8177 bytes)