The onset of synchronism can be recognized by the increase in the angle to which the vessel is
rolling. At each oscillation (half roll) this angle increases by about 1 1
2 times the wave slope. It
will be seen that this angle could soon reach dangerous limits in synchronous conditions.
The operation of stabilizers either gyro type or flume tank is beyond the present remit of this
book. Hydraulic-fin stabilisers also reduce rolling of ships