This hybrid anti-rolling system has computer-controlled moving mass, and is controlled in active and passive modes. Taking advantage of the hybrid system, it is effective at slow speed, such as drifting in oceanographic observation. This new system was equipped on board oceanographic research vessel "MIRAI" (8,687 GT) in 1997. Since then, we have been obtaining system operational data, together with rolling and wave height data at various Sea States. The system is operational up to Sea State 7, which is about 60 % of the ship time, and it can reduce rolling motion approximately 40 %. We confirmed that the system functioned very well with high reliability. In this paper, we present the system performance and its ability by analyzing operational data and sea condition data.


The observation and research vessels require a roll reduction system, which is effective under various navigation conditions for improving research activities on board. However the hybrid anti-rolling system can work effectively by its applied principal on the various navigation conditions from zero-speed to full speed where the ship encounter various rolling periods. Therefore the hybrid anti-rolling system was equipped on board of the world-biggest class oceanographic research vessel "MIRAI" (Photo. 1), which has the mission of conducting oceanographic research and research activities onboard while drifting for a long time or sailing in rough sea area. In this paper, we will introduce about the hybrid anti-rolling system, and discuss the system performance and its ability by analyzing operational data and sea condition data.

1.General descriptions of the hybrid anti-rolling system
1.1The system configuration

The specification and the side view of MIRAI are shown in table 1 and Fig. 1. To reduce rolling effectively, the hybrid anti-rolling system (hereafter called "anti-rolling device") was installed 12 m heights from the gravity center.

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