Exam Question

(a) Fin stabilisers require much less internal volume than tank stabilisers, and the internal space taken up by fins is not usually required for cargo. Typically, the space taken by a passive tank stabilising system is approximately 900 m3, which equates to approximately 20 containers.
The mass of the fin stabiliser system is also very small compared to the deadweight, whereas passive tank stabilisers take up approximately 1.5% of the displacement.
Since fin stabilisers are also much more effective than passive tanks, there is less chance of cargo movement/damage, and crews are more likely to work at optimum efficiency.
(b) In passenger ships, comfort is of prime importance, and this necessitates the best roll reduction system available. Activated fins are the most effective method of roll reduction throughout all periods of wave encounter, mainly due to their rapid response time. There are also considerations of financial income with regard consumption of food/drink and other purchases. It has been shown that excessive ship motions have a marked effect on income.