IMO PERFORMANCE STANDARDS FOR ROTI

IMO PERFORMANCE STANDARDS FOR ROTI

IMO PERFORMANCE STANDARDS FOR ROTI1. The Rate-of-Turn Indicator (ROTI) shall be capable of indicating rates of turn to starboard and toport of the ship to which it is fitted.2. The ROTI may be self-contained; alternatively it may form part of, or derive information from, anyother appropriate equipment.3. The indication required shall be provided by a centre-zero analogue type indicator (preferablycircular). Where a circular scale indicator is used, the zero shall be uppermost.4. A turn of ship to port shall be indicated on the left of the zero point and a starboard turn to the rightof the zero point. If the actual rate of turn exceeds full scale deflection, this shall be clearly indicatedon the display.5. In addition, an alphanumeric display may be provided. Positive indication of port and starboard shallbe provided on such displays.6. The length of scale in either direction from zero shall not be less than 120 mm. The sensitivity of thesystem shall ensure that a change in the rate of turn of one degree per minute is represented by adistance of not less than 4 mm on its scale.7. A linear range scale of not less than ± 30 degrees per minute shall be provided. This scale shall bemarked in intervals of one degree per minute on both sides of zero. The scale shall be marked withfigures every 10 degrees per minute. Every 10 degree mark shall be significantly longer than the 5degree mark which in turn shall be significantly longer than the one degree mark. The marks andfigures shall preferably be red or a light color on a dark background.8. Additional linear range scales may be provided.9. Damping of the ROTI shall be provided with a time constant which may be varied during operationin the range zero to at least 10 seconds.10. The indicated rate of turn shall not deviate from the actual rate of turn of the ship by more than 0.5degrees per minute plus 5 per cent of the indicated rate of turn of the ship. These values include theinfluence of earth rate.11. Periodic rolling motion of the ship with an amplitude of ± 5 degrees and period of up to 25 secondsand periodic pitching motion with an amplitude of ± 1 degree and period of up to 20 seconds shall notchange the mean value of the indicated rate of turn by more than 0.5 degrees per minute.12. The ROTI shall meet these accuracy requirements at all ship speeds up to 10 knots.13. The ROTI shall be ready for operation and comply with these standards within 4 minutes of beingswitched on.14. The design shall be such that whether operating or not, the ROTI will not degrade the performance

of any other equipment to which it is connected.15. The ROTI shall include a means of enabling the operator to verify that it is operating.