Manoj,
I don't have a definitive answer but Rakesh's reply is the one I would use unless somebody could come up with a very good reason. You are effectively applying a seismic response reduction factor, aka behaviour factor to a marine situation. I would doubt you would design and support shipboard pipework such that it had a "response reduction factor" very different from unity. Or do you ?
Wouldn't the acceleration vary significantly depending on position or are your accelerations subject to a geometrical - roll/pitch rate correction factor ? From my very limited sea going experience, you are more likely to puke on the bow than at midships.