98067 The Need for More Effective Maneuvering Signals

The Need for More Effective Manoeuvring Signals – Proposals from a Russian Master

Report No. 98-67-1

When considering circumstances of a number of collision casualties, non uniform actions of navigators are often observed. In other words, the result of a manoeuvre of one ship has been eliminated by the manoeuvre of the other; e.g. starboard turn of one ship and port turn of the other when both are approaching on reciprocal or nearly reciprocal courses. The reasons for the such actions are the misunderstanding, misinterpretation or misuse of the Rules.

Irrespective of the reasons, it is often obvious that collision could have been avoided if the parties concerned had a more effective exchange of information about their intentions. Rules 34 (a + b) of the COLREGS prescribe the use of light and whistle signals for this purpose. The light for this signal is to be an all round white light visible at a minimum range of 5 miles. Some ships may not be fitted with this light (…”if fitted”… -quotation from Rule 34(b)(iii). The whistle signal is to be audible at a distance of 2 miles under favourable conditions for ships of 200m length or more. For smaller ships this distance is respectively less. The favourable conditions comprise of conditions for spreading the sound and conditions for hearing the sound on the bridge (absence of noise). It is clear that such conditions are nor present on the bridge at any time and the sound signals are usually audible at much less distance. The light signal is during darkness only due to its technical specifications.

Rule 34 (b) states that the whistle signals may be supplemented by light signals “repeated as appropriate whilst the manoeuvre is being carried out”, Normally the signals are produced only once at the beginning of the manoeuvre. On the other hand, if the light signal is repeated ‘as appropriate’, it could easily be misinterpreted as a signal to attract attention, particularly in the case of a starboard turn. Therefore, the means to indicate manoeuvres as prescribed in the COLREGS are not effective, particularly in the daytime.

The use of VHF to communicate intended manoeuvres has several disadvantages as follows:

1 Difficulties of addressing the correct ship when several ships are in the area, particularly at night.

2 Language difficulties and the use of incorrect terminology.

3 Distraction of the watch officer from ship control, lookout and appraisal of developing situation,

All the above result in wasting time during the last minutes before the closest approach trying to call the approaching ship without success.

The conclusion is that a more effective means for indicating manoeuvres is required. The signal light should be distinguishable by day and night at a distance of not less than 5 miles. This light should be different from the one used to attract attention. To avoid additional workload for the OOW, the signal should be continuous once it has been activated and stay on until cancelled after the completion of the manoeuvre. For this purpose all round red and green flashing lights could be used for port or starboard manoeuvres respectively. These should be visible in daylight at a distance of 5 miles. Alternating flashes of red or green could be used to indicate astern propulsion.

Another promising way is an electronic based system of manoeuvring information exchange with data presentation display. Probability and welcome of such systems are mentioned by Capt Richard A Cahill in his book “Collisions and their Causes”. The ships could be fitted with a low powered tranceiver with a range of 5 – 7 miles and directional aerials which would provide the most accurate passing of the signal. The equipment should be able to operate in two ways. Transmission in reply to interrogation and transmission initiated by own ship sending data and interrogating other vessel. The ship data could include call sign, name, speed, course, bearing, distance, and type of manoeuvre intended. The basic data could be stored in the memory of the equipment and variable data input directly from gyro, log or manually. Information exchanged could be stored in the memory. The equipment could be used in all conditions of visibility.

The first step for the implementation of such a system has been made. The Maritime Safety Committee (MSC) at the 67th session in December 1996 agreed that one universal Automatic Identification System (AIS) should be implemented on a long term basis. The draft performance standards agreed by the sub committee states that AIS “should improve safety of navigation by assisting navigation of ships and operation of Vessel Traffic Services (VTS) and satisfy requirements for collision avoidance by ship-to-ship mode. The draft performance standards note that AIS should be capable of providing to ships and to competent authorities information from the ships automatically and with required accuracy and frequency to facilitate accurate tracking. Transmission of the data should be with the minimum involvement of the ship’s personnel and with a high level of availability”.

If the ship were equipped with a radar transponder with a type of signal which could be altered by the operator which would produce a signal on the radar screen of another ship nearby. For example, single dots meaning a turn to starboard, double dots meaning a turn to port and triple dots meaning a reduction of speed. This might open new ways of enhancing safety at sea.