(a) Magnetic
1) Standard compass with retransmission Class A
2) Electromagnetic with transmission
3) Transmitting magnetic heading sensor
(b) All independent of their sorroundings no extended dependency
1) Gyro
2) Fibre optics
3) Laser
4) Tuning fork
(c) Radio compass
1) GPS
2) Land station
(4) The whole thing should be considered comprehensively under the aforementioned three categories. However, this time, the performance standards for category (a) "magnetic sensor" only was taken up for consideration. As the result of the consideration, a draft recommendation on performance standards for marine transmitting magnetic heading device (TMHD) was prepared.
(5) There was a problem about accuracy with respect to the output of TMHD. Taking into account this problem and the fact that there are requirements specified for the accuracy of the reception-side devices, it was decided that static error is to be 1 and dynamic error is to be 1.5. It was agreed that the value of accuracy for dynamic error may be achieved, by using a rate gyro jointly.
(6) These standards were approved at the NAV plenary session, which decided to send them to MSC 70.
(7) Lists of accuracies stipulated for the devices which need bearing signals were distributed. It was agreed that the problem of consistency between heading sensors and reception-side devices should be considered at NAV 45 next time.
2. Performance requirements for night vision equipment for HSC
(1) The U.K., Germany, the U.S., ISO, IEC, CIRM, and Hong Kong participated in the adhoc drafting group and began consideration of the performance standards.
(2) There was a lengthy discussion over various matters regarding the paragraph of "Scope", e.g. (a) does "night" mean "perfect dark"? or does it include "moonlit night"? and (b) what situation is meant by "restricted visibility"?, but no conclusion was reached. Therefore, it was agreed that these problems should be considered within the coverage of the ISO-standards preparation work which is now taking place, because these matters can be appropriately transacted when preparing test requirements.
(3) Two types of devices, such as the equipment using visible light and the-devices employing technology which uses infrared, were assumed.
(4) The test method for the devices, and the detection target and its size were carefully examined.
(5) The experience of HSC operation in Hong Kong was used as a basis to determine the size of the target to be used in the test of detection performance.
(6) The draft performance standards for the subject item will be considered at NAV 45 next time for which each country was invited to submit comments. With regard to this matter, IEC commented on the necessity of clarification of test methods because of there being a variation in performance owing to the background temperature, meteorological and other conditions.
(7) Afterwards, the discussion with Mr. Griffiths, the IEC/TC80 secretariat regarding night vision equipment, led to the decision that ISO and IEC will jointly prepare the performance standards, as was done for the heading control systems, etc.
3 Proposal on a compensation for deviation of magnetic compasses
CIRM submitted its proposal paper under cover of NAV 44/5/7 on the method of a compensation for deviation of magnetic compasses. The contents of the proposal are important to the safety of ship navigation. Therefore, ISO supported the CIRM's proposal. However, the NAV plenary session discussed it under an agenda item of SOLAS Chapter V and finally did not adopt it.
