Signaling: How to Use Distress Signals, more

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Since the advent of electricity, man has endeavored to improve his communications systems on national and international levels. The high priority given to improving national military defense has resulted in vast technological advances in this field. The by-product of this development is a much broader spectrum and choice of communication gear for the modern sailor that has effectively lengthened his contact to shore.

Despite these advances, the isolated survivor still faces immense odds while adrift on the open ocean. Pos session of a radio does not ensure contact, just as contact does not guarantee rescue. Nevertheless, the off-shore sailor should take advantage of the sophisticated communication systems available today to maximize his chance of rescue.


The EPIRB (Emergency Position Indicating Radio Beacon) is a modified version of the earlier aviation ELT (Emergency Locating Transmitter). It’s usually equipped with both a manual and a salt water activating system. This self-contained battery-operated unit transmits an in audible, electric oscillating or “swept” tone (Figs. 3-5 through 3-7).

Fig. 3-5: E.P.I.R.B. —Emergency Position Radio Indicating Beacon..

Fig. 3-6: Mini Class B EPIRB (ACR Electronics, Inc.)

Fig. 3-7: Class A EPIRB for Attachment to life craft. (ACR Electronic, Inc.)

Fig. 3-8: Various monitoring frequencies for search & rescue.

The EPIRB transmits on the Civil VHF distress frequency of 121.5 MHz (also the aviation distress frequency) and on the military UHF distress frequency of 243.0 MHz. The effective range can vary with atmospheric conditions and battery charge. Aircraft can pick up the signal from 200 to 300 miles away, but the range at sea level is considerably less ( Fig. 3-8).

The beacon is capable of transmitting a continuous distress signal 24 hours a day for the life of the batteries. The important benefit of an EPIRB is that the survivor need not be awake or be able to see the rescue vessel in order to alert it. The models available are basically similar in function. Some contain voice capabilities for transmit ting and receiving, water-activated switches, flotation capabilities, as well as other optional features that may vary according to price.

Search and Rescue Satellites; GPS

The latest in search and rescue technology is a new type of satellite called SARSATS (Search and Rescue Satellite). These space crafts are equipped with special receivers that are tuned to standard international distress frequencies. Once orbiting, these satellites are capable of receiving distress transmissions from inexpensive emergency beacons almost any where on earth.

The first use of one such satellite was the Russian Cosmos 1,387. While in orbit the Soviet SARSAT picked up a distress signal from a downed aircraft in the wilder ness of British Columbia. The transmission from the air craft’s automatic emergency beacon was relayed from the satellite to an antenna outside Ottawa where a computer quickly obtained a navigational fix on the crash site enabling rescue within hours.

Radio Telephones (Transceivers)

Generally used in coastal waters, the VHF radio (Very High Frequency) comprises the majority of radio equipment on the average boat. VHF transmissions are “line of sight” and consequently limited by the curvature of the earth. The radio is equipped with numerous crystals or channels, depending upon the model, but all of them are equipped with channel 16, the guarded distress frequency of 156.8 MHz that is monitored by the coast guard around the clock. This frequency is also monitored by other vessels.

All radio telephones require an FCC (Federal Communications Commission) station license and all transmit ting operators are required to have an FCC operators permit.

The citizens band (CB or class D radio) is available in various sizes and vary according to price. These are low powered transmit/receive that are limited in distance.

Because of its relatively low frequency, and the wide abuse by the public in certain areas, the CB is not recognized as a legitimate emergency device by the Coast Guard. Nevertheless, because of the popularity and wide use of the CB, channel 9 is frequently monitored by the Coast Guard as an emergency channel.

Radio Distress Frequencies

The following is a list of U.S. and international distress frequencies that are guarded and monitored:

• Radiotelegraph

Distress frequency: 500 KHz

• Radiotelephones

VHF distress frequency: 121.5 MHz (The beacon distress frequency for aviation as well as shipping). UHF Military distress frequency: 243.0 MHz. Channel 16, VHF radio: (standard coastal type) distress frequency is 156.8 MHz.


The signal devices just listed normally provide operating instructions printed directly on the device itself. These instructions should be understood before you need to use the signal in an emergency. This derstand1flg will help save precious moments during the emergency and will enable you to know how to use the signals even if the instructions become illegible.


The necessity of having a balanced supply of both alert-type and location-type signal equipment cannot be over emphasized. The limitations inherent in each of the following signaling devices may not only compromise their effectiveness but can also render them useless in some situations.

Daytime Smoke Flare. These flares are adversely affected by poor visibility. They are also difficult for the rescue craft to see if it must look directly into the sun to see the flare.

Flag. Flags are influenced by wind direction and lack of wind. If the rescue boat is located directly upwind or downwind, flags will be more difficult to spot.

Lights. Lights (strobe, flash, etc.) are effective only at night.

Whistle or Horn. The most obvious limitation of a whistle or horn is distance. Your position in relation to the wind direction and the rescue vessel will also influence their effectiveness.

Mirror. Mirrors are restricted to daytime use only, with the requirement that there be a workable angle between the sun and your mirror, and the sun and the rescue craft.

Radio Beacon. A necessary requirement for a radio beacon is that the potential rescue craft be equipped with a receiver with direction finding capabilities.

Dye. Dye is adversely affected by limited visibility at sea level. It also dissipates quickly in rough seas.

Parachute, Meteor, and Rocket Flares. These types of flares are difficult to see against bright sunlight.

By illustrating the multiple uses of signaling devices, and more importantly their individual limitations, the necessity of having a full complement of signaling devices on board should be apparent to the conscientious yachtsman.


There is a general consensus as to what type of signaling devices should be included in basic provisions, but opinions vary as to quantities. The decision as to how much of each item to include is influenced by available space, your bud get, and priority evaluations.

Weigh your decisions objectively and reach a balance that will fit your particular situation without compromising your safety. The loss or malfunction of vital equipment in stressful situations is well documented.


Most distress signals have a substantial shelf life and re quire little maintenance. Batteries should be changed at least every 3 months, and light bulbs should also be checked and replaced if necessary. Salt water activated batteries have a longer shelf life than other types of batteries, if they are properly protected from moisture. Distress signals should be replaced according to the expiration date printed on them.

Storage should be given high priority in terms of location and accessibility. Distress signals should be stored in a location that allows for protection against the elements and tampering, but that also allows for instant avail ability in an emergency.

If your supply of distress signals cannot be kept in the life raft itself, (as in the case of the inflatable life raft packed in its container), then they should be securely packed and stored in an accessible location. The entire crew should be informed as to their whereabouts, and should realize the importance of successfully transferring them to the life raft in an emergency.

Distress signals should be packed in a floatable container. This will guard against loss should nervous hands slip while transferring supplies to the dinghy or raft. If you have to toss it overboard, its flotation capabilities will allow you to retrieve it later.


Radiotelegraph, as well as most other signaling methods use the Morse code to signal distress. This is, three short signals, three long, then three short again . . . pause, and repeat. This is written as dot dot dot, dash dash dash, dot dot dot:

The spoken mayday for radiotelephone is simply: “May day, mayday, mayday” spoken three times preceding any transmission or message. Then continue with the message. If possible, begin with “this is an emergency” and then give the following information:

1. Your vessel’s name and radio call letters.

2. The nature of your distress call (sinking, fire, abandoning ship, injury, etc.)

3. Your location: latitude/longitude and any additional information such as: last port of call, length of time out of last port, bearings to nearby beacons or land features, and any other information that would help locate and identify you.

4. Description of your vessel: sail/power, length, color of hull/trim, or any helpful or distinguishing markings.

5. Repeat the above information and then proceed to give the following information:

• Number of persons aboard.

• Type of assistance required.

• Prospective course, wind directions, weather conditions, and current directions.

• Survival equipment and signaling devices avail able to you.


It’s advisable to wait until you see or hear a vessel or aircraft before using a signal so you don’t waste your supply of signals.

Once the potential rescue vessel is sighted and alerted, consider the distance that the vessel must travel to reach you. Make sure you ration the use of your locate signals in accordance with the distance the rescue boat must travel to reach you.

Refer to the manufacturer’s operating instructions before activating any distress signal.

Emergency Radio

When using your emergency radio, monitor and transmit on the hour and half hour.

Use your battery power conservatively when using battery operated radios. Reserve some energy to provide search and rescue craft with a RDF (Radio Direction Finder) signal that they can home in on.

Search and rescue authorities agree that EPIRBS should be left on continuously, once activated.


Handheld Flares. Be sure to use handheld flares properly and be aware of their potential as a fire hazard. Don’t wave handheld flares ( Fig. 3-9). Use flares appropriately: smoke flares are for daytime use, red or bright burning light flares are for nighttime use.

Fig. 3-9: The illustration indicates the correct way to hold flares for effective arid safe signaling.

Projectile Flares. When signaling with alert-type devices, it may be more effective to fire them in tandem.

This specifically applies to meteor aerial flares (fire the first flare, then when it dissipates or extinguishes, fire the second one immediately). This type of sequence firing will provide a better signal for confirmation of the sighting and/or the direction.

Parachute-type flares need not be fired in tandem, as their burn times are considerably longer and most likely sufficient for an alert and confirmation.


Anything that is shiny or reflective on both sides can be used as a signaling mirror. To aim effectively, put a hole or “crosshole” of about ¼ inch in the center of the mirror, tin can, chrome piece, or whatever you are using.

• To use a heliograph, you must have a workable angle between the sun, your mirror, and the rescue craft.

• From the air, the flash from a mirror can be seen from 10 to 40 miles on a clear day.

• Even if you can only hear a plane in the distance, begin signaling with the mirror. An airplane will be able to see the flash of light before you notice the plane.

• Once the pilot has acknowledged your signal and has located you, be careful not to blind him by continuing to flash the mirror.

Practice with the mirror to improve aim rather than to wait until a “sighting” to use it the first time. Aiming can be difficult in rough water or “down-sun” angles ( Fig. 3-10).

Fig. 3-10: Proper technique for effectively using a signal mirror.

To correctly aim the mirror, hold it 3 to 4 inches from your face and sight the ship or plane through the hole in the mirror. The ray of sunlight coming through the hole onto your face can be seen in the reflective back side of the mirror. Move the mirror slowly until the spot of light from your cheek disappears into the hole, while at the same time keeping the rescue craft visible through the hole. The sun will then be properly reflected on the target.


When a vessel is sighted on the horizon, pause for a moment and try to assess its course. Rather than using up flares in a panicked fashion at the mere sight of the ship, try to decipher its course and then wait until it appears to be at its closest point. This is the point at which it will be most effective to signal the vessel.

Any distress device that is reusable such as a heliograph or a radio should be used first. This will prevent the possible waste of one-time use signals. Effective signaling will depend, of course, on the situation and your perception of it, but always try to use your signaling stores wisely and efficiently.

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