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

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Rule 34 -- Maneuvering and Warning Signals


 

Rule 34 provides the mariner with coded signals for communicating essential navigation information with other vessels in sight. To adhere to this Rule, therefore, you must maintain a proper lookout. If you did not give a required signal because you did not see another vessel, be sure the reason you did not see it was not that you did not look.

One provision in the Inland (only) Rule 34 applies all the time, whether in sight of another vessel or not. That provision requires power-driven vessels to signal when leaving a berth or dock.

Rule 34 is one of the few areas in the navigation rules where the requirements in the International Rules and Inland Rules are so different that each version must be discussed separately. Maneuvering signals are one of the major areas of difference between the two sets of Rules and may well be the most significant difference. Although the basic International and Inland maneuvering signals bear no resemblance to each other, several Rule 34 provisions are the same. Paragraph (d)/doubt signal, (e)/bend signal, and (f)/whistle separation, are identical.

What is the basic difference between the two? The International Rule maneuvering signals are often said to be signals of action: I am turning right. The Inland Rule signals, on the other hand, communicate not what you are doing now but what you intend to do. They are signals of intent: I plan to leave you to port.

Your Inland maneuvering signal is not a statement, but rather a question, or perhaps more exactly a proposition. You propose your intention to the other vessel--"I intend such-and-such a maneuver, unless you have an objection." You wait for a definite response before acting, because the other vessel has veto power. More on this later.

  

INTERNATIONAL

(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".

 

Paragraphs (a) and (b) present the basic maneuvering signals: paragraph (a) the whistle signals, and paragraph (b) the corresponding light signals.

The International Rules requirements apply to power-driven vessels in sight of another vessel (power-driven or not) when maneuvering as authorized or required by the Rules. In good visibility you may be able to see another vessel ten to twenty miles away, but you need not give signals for such long ranges because the other vessel wouldn't hear your signals. On even the largest vessels, the required range of whistles is only two miles. On smaller vessels, the required range is much less (see Annex III).

Second, a maneuver made at very long range will not likely be one "authorized or required" by the Rules. A maneuver made to get you to your destination or to avoid a buoy or other hazard, for example, is not one that need be signaled to others in sight. When vessels get close enough together to be thinking of risk of collision, then signals must be given. When a "shall not impede" situation exists, whistle signals should be given even earlier because the vessel required not to impede the passage of a larger power-driven vessel needs to know the large vessel's course changes in order to keep well clear before risk of collision arises.

If you are relatively close to another vessel and find that you must execute a maneuver not explicitly "authorized or required" by the Rules (say, to avoid running aground or into a buoy), then you would go ahead and signal that maneuver so as not to catch the other vessel by surprise.

International paragraph (a) requires signals for three maneuvers: right turn, left turn, and astern propulsion. The right or left turns may be maneuvers used by a give-way vessel to keep out of the way or by a stand-on vessel when it becomes apparent that the give-way vessel is not taking appropriate action or when collision cannot be avoided by the action of the give-way vessel alone.

The turns may be made by two vessels, both of which are directed to keep out of the way, for example, in head-on situations. Remember that Rule 8 normally requires course changes to be large enough to be readily apparent.

The third maneuver is "operating astern propulsion." This is not the same as "proceeding astern." You may of course be moving forward or astern or stopped when your astern propulsion is engaged. The state of the machinery, not motion through the water, constitutes the distinction here.

  

INTERNATIONAL

(b) Any vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals, repeated as appropriate, whilst 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 altering 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.

 

The International version of paragraph (b) adds supplemental light signals to the paragraph (a) sound signals. They are the same as the sound signals, except they are given with light, and although the sound signals must be made, the light signals are optional. The sound signals are given only once per maneuver, but the light signals may be repeated. The light and whistle need not be synchronized. Light signals may also be used to supplement the paragraph (d) doubt signal but not the paragraph (c) overtaking signals.

  

INTERNATIONAL

(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.

 

Whistle signals are sounded in overtaking maneuvers, by both the overtaking and overtaken vessels. The International paragraph (c) requirements for these signals, however, apply only in those situations where one vessel is overtaking another in a narrow channel and the overtaken vessel must maneuver to allow the other to pass. All of the requirements for this overtaking action are in Rule 9(e), but the description of the signals is in Rule 34. Both must be read together.

The signal of agreement for the overtaken vessel vessel is provided in Rule 34(c), which gives no signal for disagreement. Rule 9(e), however, says such disagreement (or doubt) may be signaled by the Rule 34(d) doubt signal, five or more short blasts.

  

INLAND

(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: one short blast to mean "I intend to leave you on my port side"; two short blasts to mean "I intend to leave you on my starboard side"; and 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 danger signal specified in paragraph (d) of this Rule and each vessel shall take appropriate precautionary action until a safe passing agreement is made.

 

We have been talking about the first three paragraphs of the International Rule 34. The Inland versions are quite different. The Inland signals of "intent and reply" represent a discussion between two vessels that must result in agreement on a course of action before the maneuver can begin.

The maneuver agreed upon will normally conform with action required by the Rules. You should avoid any agreement that involves a departure from the Rules because chances of a misunderstanding are great, especially if only whistle signals are used. Nor does local custom justify a departure from the Rules. What is "custom" for one person may be foolishness to another and news to yet another.

The first two paragraphs of Inland Rule 34 apply only to power-driven vessels meeting or crossing another power-driven vessel. Power-drivn vessels do not give signals if they are in meeting or crossing situations with vessels that are not power-driven.

Inland signals are given only for vessels that are in sight, but not for all vessels with which risk of collision exists. Signals are given only if the two vessels will meet or cross so that their closest distance of approach is less than one-half mile. For larger vessels, the signals are given well before the half-mile distance is reached, when the vessels are close enough to hear each other, in ample time for agreement to be reached before the meeting or crossing maneuver begins. The Inland Annex III audibility requirements are the same as the International: two miles for the largest vessels down to one-half mile for vessels twelve to twenty meters long.

The size and speed of a vessel, the type of waterway, and the amount of traffic will affect the distance at which maneuvering signals should be started. Smaller and slower vessels will signal at closer distances than larger and faster ones. Vessels approaching each other on open waters or from opposite directions in a river should signal earlier than vessels maneuvering in confined waters.

Vessels maneuvering in areas of heavy congestion have to take special care in signalling. If more than one vessel is close by, there may be confusion as to which is the intended recipient, especially as the signals for meeting and crossing are also those for overtaking. Other vessels, not knowing for whom the signal was intended, may signal an erroneous reply or not reply when they should.

To avoid such confusion in congested waters many mariners simply do not give whistle signals. This is illegal, unless such departure from the Rules is justified by the Rule 2 caveat allowing a departure when "necessary to avoid immediate danger." Pargraph (h) of Inland Rule 34 exuses whistle signals when agreement has been reached over the radiotelephone.

The Inland whistle signals themselves indicate an intention to leave the other vessel on one side or the other, or agreement with the proposed maneuver, or that astern propulsion is being used.

What does the phrase "I intend to leave you on my port (or starboard) side" mean? To leave another vessel means to go away from that vessel. Leaving a vessel on your port side means that the other vessel is on your port side as you go away.

In meeting situations the other vessel will be on one side before, during, and after the "meeting" and and the proper signal will be obvious. When crossing at close to right angles the side on which you leave the other vessel will also be obvious even though the vessel starts out on the opposite side. When two vessels proceeding in the same direction cross at a small angle, however, the side on which each "leaves" the other may not seem clear.

Figure 3 may make some sense of the wording of Inland Rule 34(a)(i) as applied to vessels converging on near-parallel courses. First, the term "leave" can be understood to mean when one vessel starts to draw away from the path of another vessel. This happens when the vessel crosses the projected path of the other vessel. Before it reaches this point, it is converging on the track of the other vessel, and hence is not yet "leaving" it. After it reaches this point, it leaves the other vessel on whatever side (port or starboard) the other vessel happens to be on at that time. The reference point is the intersection of the two vessels' track lines; the time for determination is the respective time that each vessel reaches the reference point. Each vessel leaves the other on the same side--that is, the passing is a port-to-port or starboard-to-starboard, never a port-to-starboard. Each vessel gives the same signal, either one blast or two.

As mentioned, the Inland Rule passing signal is a proposition for a maneuver. The other vessel must answer agreement before the maneuver can proceed. If in agreement, the other vessel responds with the same signal. If not in agreement, the other vessel sounds a signal of five or more short blasts and each vessel then takes "appropriate precautionary action." This would normally mean to slow or stop and communicate with the other vessel to identify the problem and work out a solution. You may not simply ignore a negative response to your maneuvering signal. Neither may you charge ahead if you get no response at all. You should not assume that the other vessel will always be in agreement. The lack of a reply does not indicate agreement. When you are in doubt, slow down and use your radiotelephone.

  

INLAND

(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: one flash to mean "I intend to leave you on my port side"; two flashes to mean "I intend to leave you on my starboard side"; three flashes to mean "I am operating astern propulsion";

(ii) The duration of each flash shall be about one 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.

 

As with the International Rules, the Inland Rules maneuvering signals may be supplemented by light signals. The Inland light signals, which may be either white or yellow, must be synchronized with the sound signals.

  

INLAND

(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: one short blast to mean "I intend to overtake you on your starboard side"; 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 danger signal prescribed in paragraph (d).

 

Paragraph (c) gives the Inland Rule for overtaking signals. These signals must be given in all overtaking situations involving two power-driven vessels, whether in open waters or confined. The signals are given whether or not the overtaken vessel must act to permit a safe overtaking.

The signals for overtaking are the same as for passing--one or two short blasts. Although simpler than the International signals, they are more ambiguous when more than two vessels are in the area.

The overtaken vessel signals its disagreement to the overtaking vessel by giving five or more short blasts. The overtaken vessel may not answer a two-blast signal with a one-blast (or vice versa) to indicate that the overtaking vessel should pass on the other side. If the overtaking vessel hears a doubt signal response, it should propose passing on the other side, wait until later to overtake, or contact the vessel to be overtaken on the radiotelephone.

  

INTERNTIONAL

INLAND

(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.

(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.

 

Paragraph (d), (e), and (f) of the International and Inland Rule 34 are the same. Paragraph (d) describes the "doubt" signal, also referred to in the Inland Rules as the "danger" signal. The signal is five or more short and rapid blasts, which may be supplemented by a light signal. Give the signal as soon as you are in doubt about the action of another approaching vessel--when you don't know what the other vessel is doing or when you think it is doing the wrong thing.

The signal is designed to give the operators a chance to resolve any confusion or disagreement early. Do not wait until you think you are about to crash. It is not intended as a signal to alert crew members to don their life jackets.

  

INTERNTIONAL

INLAND

(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.

(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.

 

Paragraph (e) in both versions of the Rule gives a "blind bend" signal, which you sound when you are about to come around a corner to alert other vessels to watch out for you. Listen for a reply from another vessel that may indeed be approaching from just around the bend.

  

INTERNTIONAL

INLAND

(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.

(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.

 

Paragraph (f) of both sets of the Rules seeks to avoid double signals. Because sound travels relatively slowly, a single blast sounded simultaneously on two widely separated whistles could sound like two blasts to someone ahead or astern of the signalling vessel.

International Rule 34 ends here; the Inland version has two more paragraphs.

  

INLAND

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

 

Paragraph (g) provides a signal (the same as paragraph (e)'s blind-bend signal) for vessels getting underway from a dock or berth.

  

INLAND

(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.

 

Paragraph (h) says that if you reach a passing agreement on channel 13 of your radiotelephone, you don't have to give whistle signals. It is very important that you speak over the radio with the right vessel, the one you intend to move in relation to. If you're not sure you have reached the right vessel, then you still have to sound whistle signals before executing the maneuver.

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