Effect of Moonpool on Drillship Motions

P. Sivabalan; MSP Raju

Abstract

A moonpool is meant for access to the underwater part from the onboard ship. It is a vertical opening along with the depth having an effect on the performance of the floating platform. The water motion inside the moonpool of a drillship is mainly in horizontal sloshing mode and vertical piston mode. This water motion in horizontal or in vertical mode mainly depends on the cross-section of the moonpool, encountering wave, vessel draft and so on. This water particle motion increases the vessel response when it is aligned with the vessel’s motions. A drillship with rectangular moonpool is considered for the study and the performance of the moonpool evaluated for various heading angles. The effect of water motion inside the moonpool is reflected as peaks when compared with the normal hull. The effect of moonpool on the ship motion with forward speed is also attempted in this paper.Keywords: Moonpool, piston mode, sloshing mode, response amplitude operator(RAO), water flux, water motion, downtimeCite this ArticleP.Sivabalan, M.S.P. Raju. Effectof Moonpool on Drillship Motions. Journal of Offshore Structure and Technology. 2020; 7(1): 1–5p.