Sound & Light Signals — Flash Cards

Definitions

(a) The word whistle means any sound signaling appliance capable of producing the prescribed blasts and which complies with the specifications in Annex III to these Regulations.

(b) The term short blast means a blast of about one second’s duration.

(c) The term prolonged blast means a blast of from four to six seconds’ duration.

Definitions

§ 83.32

(a) The word whistle means any sound signaling appliance capable of producing the prescribed blasts and which complies with specifications in Annex III to these Rules (33 CFR part 86).

(b) The term short blast means a blast of about 1 second’s duration.

(c) The term prolonged blast means a blast of from 4 to 6 seconds’ duration.

Equipment for Sound Signals

(a) A vessel of 12 meters or more in length shall be provided with a whistle, a vessel of 20 meters or more in length shall be provided with a bell in addition to a whistle, and a vessel of 100 meters or more in length shall, in addition, be provided with a gong, the tone and sound of which cannot be confused with that of the bell. The whistle, bell and gong shall comply with the specifications in Annex III to these Regulations. The bell or gong or both may be replaced by other equipment having the same respective sound characteristics, provided that manual sounding of the prescribed signals shall always be possible.

(b) A vessel of less than 12 meters in length shall not be obliged to carry the sound signaling appliances prescribed in paragraph (a) of this Rule but if she does not, she shall be provided with some other means of making an efficient sound signal.

Equipment for Sound Signals

§ 83.33

(a) A vessel of 12 meters or more in length shall be provided with a whistle, a vessel of 20 meters or more in length shall be provided with a bell in addition to a whistle, and a vessel of 100 meters or more in length shall, in addition, be provided with a gong, the tone and sound of which cannot be confused with that of the bell. The whistle, bell and gong shall comply with the specifications in Annex III to these Rules (33 CFR part 86). The bell or gong or both may be replaced by other equipment having the same respective sound characteristics, provided that manual sounding of the prescribed signals shall always be possible.

(b) A vessel of less than 12 meters in length shall not be obliged to carry the sound signaling appliances prescribed in paragraph (a) of this Rule but if she does not, she shall be provided with some other means of making an efficient sound signal.

Technical Details of Sound Signal Appliances

1. Whistles

(a) Frequencies and range of audibility The fundamental frequency of the signal shall lie within the range 70-700 Hz. The range of audibility of the signal from a whistle shall be determined by those frequencies, which may include the fundamental and/or one or more higher frequencies, which lie within the range 180-700 Hz (+/- 1%) for a vessel of 20 meters or more in length, or 180-2100 Hz (+/- 1%) for a vessel of less than 20 meters in length and which provide the sound pressure levels specified in paragraph 1(c) below.

(b) Limits of fundamental frequencies To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits:

(i) 70-200 Hz, for a vessel 200 meters or more in length;

(ii) 130-350 Hz, for a vessel 75 meters but less than 200 meters in length;

(iii) 250-700 Hz, for a vessel less than 75 meters in length.

(c) Sound signal intensity and range of audibility A whistle fitted in a vessel shall provide, in the direction of maximum intensity of the whistle and at a distance of 1 meter from it, a sound pressure level in at least one 1/3-octave band within the range of frequencies 180-700 Hz (+/- 1%) for a vessel of 20 meters or more in length, or 180-2100 Hz (+/- 1%) for a vessel of less than 20 meters in length, of not less than the appropriate figure given in the table below. The range of audibility in the table above is for information and is approximately the range at which a whistle may be heard on its forward axis with 90 percent probability in conditions of still air on board a vessel having average background noise level at the listening posts (taken to be 68 dB in the octave band centered on 250 Hz and 63 dB in the octave band centered on 500 Hz). 200 or more 143 2 75 but less than 200 138 1.5 20 but less than 75 130 1 120 * Less than 20 115 † 0.5 111 ‡ † When the measured frequencies lie within the range 450-800 Hz In practice the range at which a whistle may be heard is extremely variable and depends critically on weather conditions; the values given can be regarded as typical but under conditions of strong wind or high ambient noise level at the listening post the range may be much reduced.

(d) Directional properties The sound pressure level of a directional whistle shall be not more than 4 dB below the prescribed sound pressure level on the axis at any direction in the horizontal plane within ± 45 degrees of the axis. The sound pressure level at any other direction in the horizontal plane shall be not more than 10 dB below the prescribed sound pressure level on the axis, so that the range in any direction will be at least half the range on the forward axis. The sound pressure level shall be measured in that one-third octave band which determines the audibility range.

(e) Positioning of whistles When a directional whistle is to be used as the only whistle on a vessel, it shall be installed with its maximum intensity directed straight ahead. A whistle shall be placed as high as practicable on a vessel, in order to reduce interception of the emitted sound by obstructions and also to minimize hearing damage risk to personnel. The sound pressure level of the vessel’s own signal at listening posts shall not exceed 110 dB(A) and so far as practicable should not exceed 100 dB(A).

(f) Fitting of more than one whistle If whistles are fitted at a distance apart of more than 100 meters, it shall be so arranged that they are not sounded simultaneously.

(g) Combined whistle systems If due to the presence of obstructions the sound field of a single whistle or of one of the whistles referred to in paragraph 1(f) above is likely to have a zone of greatly reduced signal level, it is recommended that a combined whistle system be fitted so as to overcome this reduction. For the purposes of the Rules a combined whistle system is to be regarded as a single whistle. The whistles of a combined system shall be located at a distance apart of not more than 100 meters and arranged to be sounded simultaneously. The frequency of any one whistle shall differ from those of the others by at least 10 Hz.

2. Bell or gong

(a) Intensity of signal A bell or gong, or other device having similar sound characteristics shall produce a sound pressure level of not less than 110 dB at a distance of 1 meter from it.

(b) Construction Bells and gongs shall be made of corrosion-resistant material and designed to give a clear tone. The diameter of the mouth of the bell shall be not less than 300 mm for vessels of 20 meters or more in length. Where practicable, a power-driven bell striker is recommended to ensure constant force but manual operation shall be possible. The mass of the striker shall be not less than 3 percent of the mass of the bell.

3. Approval The construction of sound signal appliances, their performance and their installation on board the vessel shall be to the satisfaction of the appropriate authority of the State whose flag the vessel is entitled to fly.

Illustration in the handbook: 1/3-octave band level at 1 meter in dB Length of vessel referred to 2x10-5 Audibility range in meters N/m2 in nautical miles

Note: When the measured frequencies lie within the range 180-450 Hz

Note: When the measured frequencies lie within the range 800-2100 Hz

33 CFR 86 Technical Details of Sound Signal Appliances

§ 86.01 Whistles.

(a) Frequencies and range of audibility. The fundamental frequency of the signal shall lie within the range 70-700 Hz. The range of audibility of the signal from a whistle shall be determined by those frequencies, which may include the fundamental and/or one or more higher frequencies, which lie within the range 180-700 Hz (+/- 1%) for a vessel of 20 meters or more in length, or 180-2100 Hz (+/- 1%) for a vessel of less than 20 meters in length and which provide the sound pressure levels specified in paragraph (c) of this section.

(b) Limits of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits:

(i) 70-200 Hz, for a vessel 200 meters or more in length.

(ii) 130-350 Hz, for a vessel 75 meters but less than 200 meters in length.

(iii) 250-700 Hz, for a vessel less than 75 meters in length.

(c) Sound signal intensity and range of audibility. A whistle fitted in a vessel shall provide, in the direction of maximum intensity of the whistle and at a distance of 1 meter from it, a sound pressure level in at least one 1/3 rd-octave band within the range of frequencies 180-700 Hz (+/- 1%) for a vessel of 20 meters or more in length, or 180-2100 Hz (+/-1%) for a vessel of less than 20 meters in length, of not less than the appropriate figure given in Table 86.01(c) of this section. The range of audibility in Table 86.01(c) is the approximate range at which a whistle may be heard on its forward axis with 90% probability in conditions of still air on board a vessel having average background noise level at the listening posts (taken to be 68 dB in the octave band centered on 250 Hz and 63 dB in the octave band centered on 500 Hz). It is shown for informational purposes only. In practice, the range at which a whistle may be heard is extremely variable and depends critically on weather conditions; the values given can be regarded as typical but under conditions of strong wind or high ambient noise level at the listening post the range may be reduced. Table 86.01(c) 1/3rd-octave band Length of vessel in meters 2x10-5 N/m2 in nautical miles 200 or more 143 2 75 but less than 200 138 1.5 20 but less than 75 130 1 1120 Less than 20 2115 0.5 3111 1 When the measured frequencies lie within the range 180-450 Hz. 2 When the measured frequencies lie within the range 450-800 Hz. 3 When the measured frequencies lie within the range 800-2100 Hz.

(d) Directional properties. The sound pressure level of a directional whistle shall be not more than 4 dB below the sound pressure level specified in paragraph (c) of this section, in any direction in the horizontal plane within ±45 degrees of the forward axis. The sound pressure level of the whistle in any other direction in the horizontal plane shall not be more than 10 dB less than the sound pressure level specified for the forward axis, so that the range of audibility in any direction will be at least half the range required on the forward axis. The sound pressure level shall be measured in that one 1/3rd-octave band which determines the audibility range.

(e) Positioning of whistles

(i) When a directional whistle is to be used as the only whistle on the vessel and is permanently installed, it shall be installed with its forward axis directed forward.

(ii) A whistle shall be placed as high as practicable on a vessel, in order to reduce interception of the emitted sound by obstructions and also to minimize hearing damage risk to personnel. The sound pressure level of the vessel’s own signal at listening posts shall not exceed 110 dB(A) and so far as practicable should not exceed 100 dB(A).

(f) Fitting of more than one whistle. If whistles are fitted at a distance apart of more than 100 meters, they shall not be sounded simultaneously.

(g) Combined whistle systems

(i) A combined whistle system is a number of whistles (sound emitting sources) operated together. For the purposes of the Rules in Subchapter E ‡ a combined whistle system is to be regarded as a single whistle.

(ii) The whistles of a combined system shall:

(1) Be located at a distance apart of not more than 100 meters;

(2) Be sounded simultaneously;

(3) Each have a fundamental frequency different from those of the others by at least 10 Hz; and

(4) Have a tonal characteristic appropriate for the length of vessel which shall be evidenced by at least two-thirds of the whistles in the combined system having fundamental frequencies falling within the limits prescribed in paragraph (b) of this section, or if there are only two whistles in the combined system, by the higher fundamental frequency falling within the limits prescribed in paragraph (b) of this section. NOTE TO PARAGRAPH (g): If, due to the presence of obstructions, the sound field of a single whistle or of one of the whistles referred to in paragraph (f) of this section is likely to have a zone of greatly reduced signal level, a combined whistle system should be fitted so as to overcome this reduction.

(h) Towing vessel whistles. A power-driven vessel normally engaged in pushing ahead or towing alongside may, at all times, use a whistle whose characteristic falls within the limits prescribed by paragraph (b) of this section for the longest customary composite length of the vessel and its tow.

§86.02 Bell or gong

(a) Intensity of signal. A bell or gong, or other device having similar sound characteristics shall produce a sound pressure level of not less than 110 dB at 1 meter.

(b) Construction. Bells and gongs shall be made of corrosion-resistant material and designed to give clear tone. The diameter of the mouth of the bell shall be not less than 300 mm for vessels of 20 meters or more in length. Where practicable, a power-driven bell striker is recommended to ensure constant force but manual operation shall be possible. The mass of the striker shall be not less than 3 percent of the mass of the bell.

§ 86.03 Approval. [Reserved]

Illustration in the handbook: level at 1 meter in dB referred to Audibility range

Note: Parts 83-90 of Title 33 Code of Federal Regulations.

Maneuvering and Warning Signals

(a) When vessels are in sight of one another, a power-driven vessel underway, when maneuvering as authorized or required by these Rules, shall indicate that maneuver by the following signals on her whistle: − one short blast to mean “I am altering my course to starboard”; − two short blasts to mean “I am altering my course to port”; − three short blasts to mean “I am operating astern propulsion”.

(b) Any vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals, repeated as appropriate, while the maneuver is being carried out:

(i) these light signals shall have the following significance: − one flash to mean “I am altering my course to starboard”; − two flashes to mean “I am altering my course to port”; − three flashes to mean “I am operating astern propulsion”;

(ii) the duration of each flash shall be about one second, the interval between flashes shall be about one second, and the interval between successive signals shall be not less than ten seconds;

(iii) the light used for this signal shall, if fitted, be an all-round white light, visible at a minimum range of 5 miles, and shall comply with the provisions of Annex I to these Regulations.

(c) When in sight of one another in a narrow channel or fairway:

(i) a vessel intending to overtake another shall in compliance with Rule 9(e)(i) indicate her intention by the following signals on her whistle: − two prolonged blasts followed by one short blast to mean “I intend to overtake you on your starboard side”; − two prolonged blasts followed by two short blasts to mean “I intend to overtake you on your port side”.

(ii) the vessel about to be overtaken when acting in accordance with Rule 9(e)(i) shall indicate her agreement by the following signal on her whistle: − one prolonged, one short, one prolonged and one short blast, in that order.

(d) When vessels in sight of one another are approaching each other and from any cause either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by a light signal of at least five short and rapid flashes.

(e) A vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction.

(f) If whistles are fitted on a vessel at a distance apart of more than 100 meters, one whistle only shall be used for giving maneuvering and warning signals.

Maneuvering and Warning Signals

§ 83.34

(a) When power-driven vessels are in sight of one another and meeting or crossing at a distance within half a mile of each other, each vessel underway, when maneuvering as authorized or required by these Rules:

(i) Shall indicate that maneuver by the following signals on her whistle:

(1) One short blast to mean “I intend to leave you on my port side”;

(2) Two short blasts to mean “I intend to leave you on my starboard side”; and

(3) Three short blasts to mean “I am operating astern propulsion”.

(ii) Upon hearing the one or two blast signal of the other shall, if in agreement, sound the same whistle signal and take the steps necessary to effect a safe passing. If, however, from any cause, the vessel doubts the safety of the proposed maneuver, she shall sound the signal specified in paragraph (d) of this Rule and each vessel shall take appropriate precautionary action until a safe passing agreement is made.

(b) A vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals:

(i) These signals shall have the following significance:

(1) One flash to mean “I intend to leave you on my port side”;

(2) Two flashes to mean “I intend to leave you on my starboard side”;

(3) Three flashes to mean “I am operating astern propulsion”;

(ii) The duration of each flash shall be about 1 second; and

(iii) The light used for this signal shall, if fitted, be one all-round white or yellow light, visible at a minimum range of 2 miles, synchronized with the whistle, and shall comply with the provisions of Annex I to these Rules (33 CFR part 84).

(c) When in sight of one another:

(i) A power-driven vessel intending to overtake another power-driven vessel shall indicate her intention by the following signals on her whistle:

(1) One short blast to mean “I intend to overtake you on your starboard side”;

(2) Two short blasts to mean “I intend to overtake you on your port side”; and

(ii) The power-driven vessel about to be overtaken shall, if in agreement, sound a similar sound signal. If in doubt she shall sound the signal prescribed in paragraph (d) of this Rule.

(d) When vessels in sight of one another are approaching each other and, from any cause, either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by a light signal of at least five short and rapid flashes.

(e) A vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. This signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction.

(f) If whistles are fitted on a vessel at a distance apart of more than 100 meters, one whistle only shall be used for giving maneuvering and warning signals.

(g) When a power-driven vessel is leaving a dock or berth, she shall sound one prolonged blast.

(h) A vessel that reaches agreement with another vessel in a head-on, crossing, or overtaking situation, as for example, by using the radiotelephone as prescribed by the Vessel Bridge-to-Bridge Radiotelephone Act (85 Stat. 164; 33 U.S.C. 1201 et seq.), is not obliged to sound the whistle signals prescribed by this Rule, but may do so. If agreement is not reached, then whistle signals shall be exchanged in a timely manner and shall prevail.

One prolonged = making way. Two prolonged = stopped. One prolonged + two short = everything else.

Memory aid written by us — not part of the regulation. Rule 35 governs.

Sound Signals in Restricted Visibility In or near an area of restricted visibility, whether by day or night, the signals prescribed in this Rule shall be used as follows:

(a) A power-driven vessel making way through the water shall sound at intervals of not more than 2 minutes one prolonged blast.

(b) A power-driven vessel underway but stopped and making no way through the water shall sound at intervals of not more than 2 minutes two prolonged blasts in succession with an interval of about 2 seconds between them.

(c) A vessel not under command, a vessel restricted in her ability to maneuver, a vessel constrained by her draft, a sailing vessel, a vessel engaged in fishing and a vessel engaged in towing or pushing another vessel shall, instead of the signals prescribed in paragraphs (a) or (b) of this Rule, sound at intervals of not more than 2 minutes three blasts in succession, namely one prolonged followed by two short blasts.

(d) A vessel engaged in fishing, when at anchor, and a vessel restricted in her ability to maneuver when carrying out her work at anchor, shall instead of the signals prescribed in paragraph (g) of this Rule sound the signal prescribed in paragraph (c) of this Rule.

(e) A vessel towed or if more than one vessel is towed the last vessel of the tow, if manned, shall at intervals of not more than 2 minutes sound four blasts in succession, namely one prolonged followed by three short blasts. When practicable, this signal shall be made immediately after the signal made by the towing vessel.

(f) When a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and shall give the signals prescribed in paragraphs (a) or (b) of this Rule.

(g) A vessel at anchor shall at intervals of not more than one minute ring the bell rapidly for about 5 seconds. In a vessel of 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely one short, one prolonged and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.

(h) A vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (g) of this Rule and shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell. A vessel aground may in addition sound an appropriate whistle signal.

(i) A vessel of 12 meters or more but less than 20 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.

(j) A vessel of less than 12 meters in length shall not be obliged to give the above-mentioned signals but, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.

(k) A pilot vessel when engaged on pilotage duty may in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule sound an identity signal consisting of four short blasts.

Sound Signals in Restricted Visibility

§ 83.35

In or near an area of restricted visibility, whether by day or night, the signals prescribed in this Rule shall be used as follows:

(a) A power-driven vessel making way through the water shall sound at intervals of not more than 2 minutes, one prolonged blast.

(b) A power-driven vessel underway but stopped and making no way through the water shall sound, at intervals of not more than 2 minutes, two prolonged blasts in succession, with an interval of about 2 seconds between them.

(c) A vessel not under command; a vessel restricted in her ability to maneuver, whether underway or at anchor; a sailing vessel; a vessel engaged in fishing, whether underway or at anchor; and a vessel engaged in towing or pushing another vessel shall, instead of the signals prescribed in paragraphs (a) or (b) of this Rule, sound at intervals of not more than 2 minutes, three blasts in succession, namely, one prolonged followed by two short blasts.

(d) [Reserved]

(e) A vessel towed or if more than one vessel is towed the last vessel of the tow, if manned, shall at intervals of not more than 2 minutes sound four blasts in succession, namely, one prolonged followed by three short blasts. When practicable, this signal shall be made immediately after the signal made by the towing vessel.

(f) When a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and shall give the signals prescribed in paragraphs (a) or (b) of this Rule.

(g) A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds. In a vessel of 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely, one short, one prolonged and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.

(h) A vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (g) of this Rule and shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell. A vessel aground may in addition sound an appropriate whistle signal.

(i) A vessel of 12 meters or more but less than 20 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.

(j) A vessel of less than 12 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.

(k) A pilot vessel when engaged on pilotage duty may, in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule, sound an identity signal consisting of four short blasts.

(l) The following vessels shall not be required to sound signals as prescribed in paragraph (g) of this Rule when anchored in a special anchorage area designated by the Coast Guard:

(i) A vessel of less than 20 meters in length; and

(ii) A barge, canal boat, scow, or other nondescript craft.

Signals to Attract Attention If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel. Any light to attract the attention of another vessel shall be such that it cannot be mistaken for any aid to navigation. For the purpose of this Rule the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided.

Signals to Attract Attention

§ 83.36

If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel.

Distress Signals When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV to these Regulations.

Illustration in the handbook: DISTRESS SIGNALS 72 COLREGS

Distress Signals

§ 83.37

When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV of these Rules (33 CFR part 87) *. The distress signals for inland waters are the same as those displayed on the facing page for international waters, with the exception of this high intensity flashing white light.

Illustration in the handbook: A high intensity white light flashing at regular intervals from 50 to 70 times per minute. Inland only.

Distress Signals

1. The following signals, used or exhibited either together or separately, indicate distress and need of assistance:

(a) a gun or other explosive signal fired at intervals of about a minute;

(b) a continuous sounding with any fog-signaling apparatus;

(c) rockets or shells, throwing red stars fired one at a time at short intervals;

(d) a signal made by any signaling method consisting of the group. . . – – – . . . (SOS) in the Morse Code;

(e) a signal sent by radiotelephony consisting of the spoken word “Mayday”;

(f) the International Code Signal of distress indicated by N.C.;

(g) a signal consisting of a square flag having above or below it a ball or anything resembling a ball;

(h) flames on the vessel (as from a burning tar barrel, oil barrel, etc.);

(i) a rocket parachute flare or a hand flare showing a red light;

(j) a smoke signal giving off orange-colored smoke;

(k) slowly and repeatedly raising and lowering arms outstretched to each side;

(l) a distress alert by means of digital selective calling (DSC) transmitted on:

(i) VHF channel 70, or

(ii) MF/HF on the frequencies 2187.5 kHz ‡, 8414.5 kHz, 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz;

(m) a ship-to-shore distress alert transmitted by the ship’s Inmarsat or other mobile satellite service provider ship earth station;

(n) signals transmitted by emergency position-indicating radio beacons;

(o) approved signals transmitted by radiocommunication systems, including survival craft radar transponders.

2. The use or exhibition of any of the foregoing signals except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals is prohibited.

3. Attention is drawn to the relevant sections of the International Code of Signals, the International Aeronautical and Maritime Search and Rescue Manual, Volume III, and the following signals:

(a) a piece of orange-colored canvas with either a black square and circle or other appropriate symbol (for identification from the air);

(b) a dye marker. August 1, 2013. (78 FR 42102).

Note: The U.S. Coast Guard terminated monitoring DSC safety and distress frequency 2187.5 kHz on

33 CFR 87 Distress Signals

§ 87.1 Need of assistance The following signals, used or exhibited either together or separately, indicate distress and need of assistance:

(a) A gun or other explosive signal fired at intervals of about a minute;

(b) A continuous sounding with any fog-signaling apparatus;

(c) Rockets or shells, throwing red stars fired one at a time at short intervals;

(d) A signal made by any method consisting of the group . . . – – – . . . (SOS) in the Morse Code;

(e) A signal sent by radiotelephony consisting of the spoken word “Mayday”;

(f) The International Code Signal of distress indicated by N.C.;

(g) A signal consisting of a square flag having above or below it a ball or anything resembling a ball;

(h) Flames on the vessel (as from a burning tar barrel, oil barrel, etc.);

(i) A rocket parachute flare or a hand flare showing a red light;

(j) A smoke signal giving off orange-colored smoke;

(k) Slowly and repeatedly raising and lowering arms outstretched to each side;

(l) A distress alert by means of digital selective calling (DSC) transmitted on:

(i) VHF channel 70, or

(ii) MF/HF on the frequencies 2187.5 kHz ‡, 8414.5 kHz, 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz;

(m) A ship-to-shore distress alert transmitted by the ship’s Inmarsat or other mobile satellite service provider ship earth station;

(n) Signals transmitted by emergency position-indicating radio beacons;

(o) Signals transmitted by radiocommunication systems, including survival craft radar transponders meeting the requirements of 47 CFR 80.109; and

(p) A high intensity white light flashing at regular intervals from 50 to 70 times per minute.

§ 87.02 Exclusive use. The use or exhibition of any of the foregoing signals except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals is prohibited.

§ 87.03 Supplemental signals. Attention is drawn to the relevant sections of the International Code of Signals, the International Aeronautical and Maritime Search and Rescue Manual, Volume III, the International Telecommunication Union Radio Regulations, and the following signals:

(a) A piece of orange-colored canvas with either a black square and circle or other appropriate symbol (for identification from the air);

(b) A dye marker. August 1, 2013. (78 FR 42102).

Note: The U.S. Coast Guard terminated monitoring DSC safety and distress frequency 2187.5 kHz on

White flashing means ATTENTION at sea (Rule 36) but DISTRESS inland: Inland 33 CFR 87.1(p) lists a high intensity white light flashing 50-70 times a minute as a distress signal. Do not carry the international habit onto inland waters.

Memory aid written by us — not part of the regulation. Rule 37 governs.