Inland Navigation Rules

Part D - Sound and Lights Signals

(a) A vessel at anchor shall exhibit where it can best be seen:

(b) A vessel of less than 50 meters in length may exhibit an all-round white light where it can best be seen instead of the lights prescribed in paragraph (a) of this Rule.
(c) A vessel at anchor may, and a vessel of 100 meters or more in length shall, also use the available working or equivalent lights to illuminate her decks.
(d) A vessel aground shall exhibit the lights prescribed in paragraph (a) or (b) of this Rule and, in addition, if practicable, where they can best be seen:

(e) A vessel of less than 7 meters in length, when at anchor, not in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate, shall not be required to exhibit the lights or shapes prescribed in paragraphs (a) and (b) of this Rule.
(f) A vessel of less than 12 meters in length, when aground, shall not be required to exhibit the lights or shapes prescribed in subparagraphs (d)(i) and (ii) of this Rule.
(g) A vessel of less than 20 meters in length, when at anchor in a special anchorage area designated by the Secretary, shall not be required to exhibit the anchor lights and shapes required by this Rule.

Rule 30 Small craft less than 7 meters in length are not required to show an anchor light or shape if anchored out of the way of all other water traffic. Larger craft and vessels must comply with Rule 30 wherever anchored (see Inland exception below) - this includes the showing of an "anchor ball" dayshape, a requirement that is all too frequently ignored by small craft.

Any vessel at anchor may, and vessels of 100 or more meters in length must, show deck or working lights to increase her visibility to other vessels. A vessel made fast to a mooring is "at anchor." A vessel dragging its anchor is not "made fast to the bottom" and, therefore, is not a vessel at anchor, but rather a vessel underway.

The Inland Rules only provide for "special anchorage areas" in which anchor lights and shapes are not required for craft less than 20 meters in length. These are generally established off marinas and yacht clubs where boats are left unmanned on moorings for days at a time and electric power is not available for showing anchor lights. There are only a limited number of these; they are described in Coast Pilots and are outlined on applicable large-scale charts. There is no provision in the International Rules for areas where anchor lights and shapes are not required.

International Rule 30(d) requires vessels of 12 meters or more length when aground to show the three "anchor balls" day signal or two all-round red lights at night; few small craft are equipped to meet this requirement, and thus, nearly all fail to comply. The Inland Rules have the same requirement, but add "if practicable" without defining the limits of practicability.

A vessel is not considered "aground" for the purposes of this Rule if she is intentionally placed in contact with the bottom or against the bank to hold her position; in this case, the vessel is underway with no way on.

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Rule 31 Seaplanes

Where it is impracticable for a seaplane to exhibit lights and shapes of the characteristics or in the positions prescribed in the Rules of this Part, she shall exhibit lights and shapes as closely similar in characteristics and position as possible.

Rule 31 When on the water, a seaplane (or amphibian) is a "vessel" in terms of the Navigation Rules. "In this part" refers to Rules 20 through 30.

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Rule 32 Definitions

(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.
(b) The term "short blast" means a blast of about 1 second duration.
(c) The term "prolonged blast" means a blast of from 4 to 6 seconds' duration.

Rule 32 This Rule broadens the term "whistle" to include sound-producing devices that are more likely to be found on smaller vessels - if it can make a sound that meets the requirements of the Rules and Annex III, it's a whistle. Note that there are only two kinds of whistle blasts - short and prolonged; the term "long blast" does not appear in either set of the Navigation Rules.

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Rule 33 Equipment for Sound Signals

(a) A vessel of 12 meters or more in length shall be provided with a whistle and a bell, 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 lll to these Rules. 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.

Rule 33 There are only three types of sound-signal equipment mentioned in the Rules - whistle, bell, and gong, with the latter only required on vessels 100 meters or more in length. Even if the sound of a bell or gong can be created by other means (electronic), manual sounding must always be possible. There is no use of the term "fog horn" in the Rules; "fog" signals are sounded on the same whistle as used for other purposes.

Automatically timed fog signals are widely used, but caution is advised lest your signals get in synchronization with those of another vessel and you don't hear that vessel.

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Rule 34 Maneuvering and Warning Signals

(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:

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

(c) When in sight of one another:

(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. This 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 by using the radiotelephone as prescribed by the Bridge-to-Bridge Radiotelephone Act (85 Stat. 165; 33 U.S.C. 1207), 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.

Rule 34 This Rule contains the most significant variations between the International and Inland Rules - and these differences must be clearly understood.

The International Rules whistle signals for power-driven vessels underway in sight of each other are signals of actions being taken - they are required between two such vessels in sight of one another, and do not require a reply. The Inland Rules whistle signals for power-driven vessels are signals of intent - they are required in sight of one another and are meeting or crossing at a distance within half a mile of each other. These signals require a reply.

The meanings of the one and two short-blast signals are different in the two sets of Rules. Be sure of which set governs the waters you are on at all times so that you may properly sound your signals and interpret the signals of other vessels. These signals are not to be used in conditions of restricted visibility. Fortunately, the very important signal of doubt or danger - five or more short and rapid blasts - is the same on all waters.

The three-blast sound signal in both sets of Rules has the same meaning. "Operating astern propulsion" means only that; it does not necessarily mean that the vessel has stopped or is making sternway. The deciding factor is the operation of the propulsion machinery, not the movement of the vessel. In both sets of Rules, the one, two, three, and five or more short blast signals may be supplemented by light signals with the corresponding number of one-second flashes at one-second intervals. Note that the light signals may not be substituted for the sound signals.

The International Rules require that this light be white; the light signals need not be synchronized with the whistle blasts, and may be repeated after an interval of ten seconds. The Inland Rules allow either white or yellow; the light flashes must be synchronized with the whistle blasts and cannot be repeated separately. The required visibility ranges are different for the two sets of Rules.

Note: that Rule 34 is applicable only to power-driven vessels - vessels under sail are not required to sound maneuvering signals (unless, of course, they are also using mechanical propulsion, in which case they are not sailing vessels). In waters governed by the International Rules, a power-driven vessel may sound a whistle signal to a sailing vessel to indicate action being taken. However, in Inland Rules waters, a power-driven vessel should not sound whistle signals of intent to a sailing vessel, as that vessel cannot reply.

In overtaking situations, the signals of the International Rule are applicable only if the encounter occurs in a narrow channel and the overtaken vessel must maneuver to allow safe passage of the other. In the Inland Rules, the signals are required in all circumstances if the vessels will come within a half-mile of each other.

The signals of the two sets of Rules are quite different, with the International being more complex.

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Rule 35 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, 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) 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.
(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.
(f) 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.
(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.
(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.
(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.
(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:

Rule 35 International Rule 35(f) and Inland Rule 35(e) refer to a "composite unit" of a rigidly connected pushing vessel and vessel being pushed. This is a rare situation, as the normal means of connection of wires and winches does not meet this definition. See also Rule 24(b).

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Rule 36 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.

Rule 36 Note: carefully that a signal "to attract the attention of another vessel" is not a distress signal. It is often used by fishing vessels with nets out. A searchlight should be shown only in the direction of the danger; it should never be directed toward the other vessel, lest it blind the helmsman. The International Rule specifically eliminates the use of strobe lights for the purpose of attracting attention. The Inland Rule does not have this prohibition, but it should be noted that such a light is listed as a distress signal in waters subject to these Rules.

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Rule 37 Distress Signals

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

Rule 37 Because the primary intent of the Navigation Rules is to prevent collisions, the details of distress signals are not included in the basic Rules - only a reference to Annex IV, where they may be found.