Handbook of the Nautical Rules of the Road by Llana & Wisneskey

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Rule 35 -- Sound Signals in Restricted Visibility


 

Rule 35 tells us about what are colloquially called "fog signals." The Rules themselves do not use the term because restricted visibility can be caused by conditions other than fog. Rule 3 attributes restricted visibility to "fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes."

In the rest of the discussion, we will refer to the signals as "restricted-visibility signals," but when people mention "fog" signals, this is what they are talking about. There are only small differences between the International and Inland versions of the Rule.

  

INTERNATIONAL

INLAND

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

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

 

The signals in Rule 35 are used in conjuction with Rule 19 (Conduct of Vessels in Restricted Visibility) and as in that Rule, apply both in or near an area of restricted visibility, and by day or night. How bad must the visibility become before you have to give the signals?

Giving the signals when nobody is close enough to hear them will only dull your hearing and deprive the off-watch of their sleep. Use the signals when you can't see as far as your whistle can be heard. Minimum audibility range is two miles for large ships, but they may be heard three or four miles away depending on the particular whistle and the atmospheric conditions.

  

INTERNATIONAL

INLAND

(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.

(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.

 

Paragraphs (a) and (b) give the most common signals, those for ordinary power-driven vessels underway. The signal is one prolonged blast or two, depending on whether the vessel is making way or stopped. If you hear a two-blast signal, don't assume that the vessel making it will stay stopped.

Rule 32 defines a prolonged blast as one lasting from four to six seconds. The required interval between signals is two minutes or less. Don't let a signal repeated every thirty seconds or every minute confuse you. Shorter intervals are desirable when other vessels are near.

  

INTERNATIONAL

INLAND

(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.

(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.

 

Paragraph (c) gives a third signal for vessels that are likely to be less maneuverable than ordinary power-driven vessels, although Rule 19 does not treat them any differently from ordinary power-driven vessels. Nevertheless, the special signal--one prolonged blast followed by two short--does give other vessels more information. If and when the impaired vessels finally do loom into view, however, the Rules in force change and they may become stand-on vessels.

The impaired vessels covered by paragraph (c) include those not under command, restricted in ability to maneuver, sailing, and engaged in towing or pushing another vessel. The International version also includes vessels constrained by draft (a concept rejected in the Inland Rules).

  

INTERNATIONAL

(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.

 

Vessels engaged in fishing while anchored and vessels restricted in ability to maneuver while anchored must also sound one prolonged plus two short blasts. This requirement, treated differently in the two versions, is more successful in the International version. The issue is whether the hampered and anchored vessels give both the signal for hampered vessels and the paragraph (g)/International or (f)/Inland signal for anchored vessels.

International paragraph (d) tells us to give the paragraph (c) signal instead of the signal for anchored vessels. The Inland version attempts to treat the special case of vessels fishing or restricted in ability to maneuver while also anchored within paragraph (c) rather than adding a separate paragraph.

Inland paragraph (c) (like the International version) says to use the one-long, two-short signal, instead of the paragraph (a) and (b) signals, and also paragraph (f) signals for anchored vessels. The Inland Rule would seem, then, to require anchored vessels engaged in fishing or restricted in ability to maneuver to give both the paragraph (c) and paragraph (f) signals.

To be on the safe side, you had better follow the wording, even though the drafters of the Inland Rules probably intended much the same message as the International version. Few vessels will be affected by this particular provision.

  

INTERNATIONAL

INLAND

(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.

(d) 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.

 

These identical paragraphs address the signals to be given by barges and other vessels towed astern. Unmanned towed vessels do not have to give signals nor would a manned barge if it was not the last vessel in the tow. Nevertheless, the prudent mariner would arrange, if possible, for automatic signals to be given on the last barge of any long tow.

  

INTERNATIONAL

INLAND

(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.

(e) 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.

 

Paragraph (f/e) is the sound-signal counterpart of Rule 24(b), which requires rigidly connected tug-barge composites to be lighted as a single power-driven vessel. The corresponding Rule 35 provision similarly treats these composite units as ordinary power-driven vessels. Towing vessels that push ahead but are not rigidly connected use the sound signals in paragraph (c), and the barges being pushed ahead do not sound any signals.

  

INTERNTIONAL

INLAND

(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.

(f) 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.

 

The sound signals for anchored vessels in or near restricted visibility are relatively straighforward. All vessels sound their bells, after which larger vessels sound their gongs. Any vessel may also use a whistle signal. The whistle signal can be heard farther away than the bell and should be used when background noise is high or when another vessel is approaching too rapidly. The whistle signal also gives better indication of your position.

  

INTERNTIONAL

INLAND

(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.

(g) A vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (f) 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.

 

The bell and gong signals required for anchored vessels are also required for vessels aground (another form of anchoring), except that the bell signal is modified by the distinctive three rings before and after the usual five seconds of rapid ringing. You are also permitted to give an "appropriate whistle signal."

The Defense Mapping Agency's H.O. 102 International Code of Signals is full of signals. For example, if you were on a coral reef and knew other vessels were headed your way, you might want to send the Morse code for "U" -- two short plus one prolonged blast -- to signal "You are running into danger."

  

INTERNTIONAL

INLAND

(i) 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.

(h) 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.

 

International paragraph (i) and Inland paragraph (h) exempt small vessels from making Rule 35 sound signals, but only on the condition that they give some other signal that can be understood (as coming from a small vessel) and heard early enough to prevent a collision. Any alternative signal must be repeated every two minutes or less, the same as for the prescribed signals. Note that this exemption dovetails with the Rule 33(b) provision saying that vessels less than twelve meters need not carry sound-signal appliances meeting the technical specifications of Annex III.

  

INTERNATIONAL

INLAND

(j) 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.

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

 

Pilot vessels have their own whistle signal for restricted visibility. It is four short blasts. Count them. The doubt signal described in Rule 34(d) is five or more short blasts and is only for use between vessels in sight of each other.

It is possible, however, for both signals to be heard in the same area; Rule 35 requirements apply in or near an area of of restricted visibility, and unless the visibility is zero, vessels will come into sight of each other as they get closer. Remember, four shorts blasts signal a pilot vessel.

  

INLAND

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

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

(ii) a barge, canal boat, scow, or other non-descript craft.

 

The Inland version of Rule 35 contains this additional paragraph covering signals in designated "special anchorage areas." A list of these areas is contained in Title 33 of the Code of Federal Regulations, Part 110. About a hundred of these areas are scattered around the country. Small vessels and unpowered vessels normally towed need not give signals if they are anchored in one of these places.

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