COMMUNICATIONS AND NAVIGATIONAL AIDS OF A MODERN LIFEBOAT by Lieutenant Ernest Gough, RN STAFF OFFICER (COMMUNICATIONS), RNLISEEING AN OFFSHORE LIFEBOAT for the first time, you may wonder why she has so many antennae and gadgets sprouting out from her superstructure. The antennae are, of coufse, the ship's aerials, each designed for a specific job; they, like the other similar fittings, are above-decks evidence of the electronic eyes, ears and mouth now at the service of the crew in the wheelhouse. Through them the lifeboat crew can obtain upto- the-minute information from the outside world, and in turn pass back their own urgent messages.

When the new Arun class lifeboat was introduced into service she was fitted with the latest communications and navigational aids, and at the foot of this page is a photograph of an Arun on which each electronic deck fitting has been numbered.

Come on board for a guided tour. . . .

1. The smaller of the whip aerials on the starboard side of the Arun's wheelhouse is for the very high frequency (VHF) frequency modulated (FM) radio used to communicate with the Coastguard and Coast Radio Stations, other ships, search and rescue (SAR) units including helicopters, Royal Navy ships and, of course, any casualty which is fitted with VHF radio.

2. There is an even smaller whip aerial on the port side. It is a similar type of equipment, that is VHF, but it is amplitude modulated (AM) and is used to communicate with French helicopters in combined services with Arun class lifeboats in the waters surrounding the Channel Islands. This aerial need not be fitted on Aruns at other stations.

3. The larger of the whip aerials on the port side acts as the search aerial for a medium frequency (MF) receiver. It enables the lifeboat to maintain a constant listening watch on the distress frequency, 2182 kHz, irrespective of the frequency to which her main MF radio may be tuned.

4. The whip aerial at position 3 is also used in conjunction with the loop aerials seen at position 4. These are fixed Bellini Tosi direction finding (DF) loops which enable the lifeboat to take radio direction finding bearings for navigational purposes or to home on to a casualty.

5. The larger whip aerial on the starboard side, similar to the one at position 3, is for the main medium frequency radio which can be tuned to nine different transmitting channels, including the distress frequency 2182 kHz, and eleven receiving channels.Because the two larger whip aerials are of the same design, should the transmitter aerial (5) be damaged in rough weather or when going alongside a heavily rolling casualty, the tcansmitter can very quickly be restored by changing over the elements from the aerial at position 3; this can be done without having to retune the transmitter.

6. Here you will see the radar scanner; its display is in the wheelhouse, starboard side, alongside the coxswain. Continually rotating, the scanner picks up the shapes of coastline, rocks and ships and, with a rotating beam, sketches them in on the wheelhouse display in distance ranges of mile, 1-J, 3, 6, 12 and 24 miles, thus presenting the coxswain with an electronic chart, constantly corrected, of the waters through which he is steering, and helping him to locate the casualty for which he may be searching.

7. The dark cylindrical object standing up on the port side is the amplifier for the Decca navigator mark 21 receiver.

Again, this receiver is in the wheelhouse at the chart position. Continually reading signals from groups of shore transmitters, the Decca presents the coxswain, at any time, with a set of numbers which, referred to a special lattice chart, immediately plot for him the position of the lifeboat.

8. The little white, round, cyclindrical object is the sensor for the Decca 350 automatic pilot. It can sense when the lifeboat moves off a pre-set course and actuates the rudders automatically to regain the course to be steered, thus relieving the coxswain of the need to steer the boat manually during long passages in open water.

9. At the top of the mast is a blue flashing light which identifies the lifeboat, when launched on service, as a search and rescue unit in the same way as an ambulance or a fire engine is distinguished on shore.

10. Alongside the coxswain when he is conning the lifeboat from the upper steering position is the echo sounder indicator, which gives an immediate indication of the depth of water below the boat by using a neon light, while . . .

11. ... in the wheelhouse at the chart table is a second echo sounder of the recorder type which makes a permanent record on paper of the depth being encountered.The transducers through which the echo sounder signals are transmitted and, after being 'bounced' off the sea bed, received back again cannot, of course, be seen as they are fixed to the hull bottom on either side of the keel.

The Arun is also fitted with a five-way intercom unit so that the coxswain can speak to each of the compartments, the upper steering position and to the crew member on the fore deck.

That is a brief description of the electronic equipment available to the crew of an Arun; other lifeboat classes are similarly, though not identically, equipped. Every offshore lifeboat has a minimum of MF radio, VHF radio and echo sounder. The majority have a direction finder on the MF radio and over 100 are fitted with radar. All newly constructed lifeboats have radar and direction finder installed on building.

Inshore lifeboats are all fitted with VHF radio only.

Navigational aids are there for the coxswain to use in his own wheelhouse as the need arises, but the radios are obviously for two-way conversation.

How, then, are radio communications afloat organised? From the diagram on this page it will be quickly seen that each search and rescue station or mobile unit is fitted with radio equipment which allows it to work on specific frequencies.

These frequencies and the traffic allocated to them are listed below: Medium Frequency (MF) 2182kHz International distress and calling frequency 1.6 mHz various Coastguard working frequency 2241 kHz Ship to ship frequency 3023.5kHz Scene of action search and rescue co-ordination frequency Very High Frequency (VHF) Channel 16 156.80 mHz International distress and calling frequency Channel 0 156.00 mHz Coastguard working frequency Channel 6 156.30 mHz Ship to ship frequency Channel 12 156.60 mHz Port control Channel 14 156.70 mHz Port control Although the diagram may look rather complicated, lifeboat communications are really quite simple. The golden rule is that the frequency or channel chosen should always be one that is common to all the units taking part in the rescue service. For example: a. Units involved: Casualty (fitted with MF and VHF radio) Coast Radio Station Merchant ship Lifeboat 2182 kHz MF and VHF Channel 16 would be used.

b. Units involved: Casualty with no radio near to shore Warship standing by Coastguard stationLifeboat VHF Channel 16 would be used.

c. Units involved: Casualty with no radio near to shore Coastguard station Inshore lifeboat SAR helicopter Provided no help is required from other shipping in the area VHF Channel 0 would be used.

d. Units involved: French fishing vessel (casualty, offshore) British tanker standing by Nimrod aircraft Coastguard Headquarters Lifeboat 2182 kHz MF would be used.

The other working frequencies that are available between individual units would only be used when the matters to be discussed are of no interest to others taking part in the operation. Any information affecting the rescue operation received on a working frequency not common to all units is passed to the coordinating authority and then relayed on the common net to all concerned, usually by means of frequent situation reports.

A lifeboat launches on service on MF 2182 kHz and VHF Channel 16 and establishes communications with the primary MF radio station and the Coastguard VHF radio station on those frequencies.

All further communication is carried out on 2182 kHz and VHP Channel 16, except that by prior arrangement with the Coastguard, provided it is unlikely that help from ships at sea will be needed and the lifeboat has been launched to a service which has not been initiated through a Coast Radio Station (e.g.

Mayday call), then the Coastguard station MF working frequency (1.6 mHz) or VHF Channel 0 may be used. This, of course, leaves the international distress frequencies free for other emergencies.

Until recently the necessary maintenance on electronic equipment in our lifeboats was carried out under contracts negotiated with the various suppliers.

Generally this scheme worked out very well, but there were of course problems in arranging for the engineers to visit lifeboats at remote stations, and it was expensive. Following an evaluation of this policy by the Committee of Management, it was decided that all maintenance should be done by the RNLI's own staff.

This system has now been introduced almost completely, and it is working extremely efficiently. The communications department has developed a planned maintenance scheme which is proving of great benefit. If there is a serious problem at any lifeboat station, it is a straightforward matter to arrange for one of our own technical staff to deal with it without delay. There is no doubt that this new scheme is solving many problems, and costs appreciably less.

That is a brief introduction to the electronic equipment carried on board a modern lifeboat. We live in a sophisticated age and without doubt electronic development has put most wonderful aids into the hands of lifeboat crews. It must not be forgotten, however, that they are only aids: that is all they claim to be. They are far-reaching extensions of the senses of the crew, but they can never replace the observant eye, the perceptive ear, the immediate hail of the experienced seafarer. Nor can they fully take the place of the simpler, familiar tools of communication and navigation, always to hand; loudhailer, signalling lamp, flags, flares, compass and leadline.

Be it simple or sophisticated, in the end an aid can only be as good as the man who is operating it; as in all spheres of lifeboat work, when a storm is blowing, the sea very rough and confused, it is the calibre of the crew member that counts..