roll prediction

[NavArch007]

Dear All,

Im in the process of doing a seakeeping study on a vessel with heavy rolling. I intend to use strip theory to calculate the resonse of the vessel.

Roll motion will be defined by calculating an accurate roll damping ratio for the vessel.

Without any stabilizing (i.e more technically refered to as motion damping devices) ; im getting a damping ratio of 0.06 (rms roll 19 degrees). With a pair of fins, the damping ratio is increase to 0.35 at top speed of 24 knots.( rms roll 6 degrees in beam seas)

Is it typical to get such an increase in the roll damping ratio ( i.e reduction in rms roll) for such for a quick V-hull patrol boat (APPROX. 25M LENGTH , 24 KNOTS).

Thanks in advance.

NavArch007

[FAST FRED]

Cant help with the math , But roll is of most interest for gun firing platforms.

The big concern will be the G loads impacting waves at speed.

3G is acceptable by most military crews (young and fit) , but even with $8000 seats hard on most folks.

FF