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

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Annex I -- Positioning and Technical Details of Navigation Lights


Annex I tells us how navigation lights have to peform and where they must be located. It doesn't say what lights to display--the Rules do that. Annex I also describes the size, color, and spacing for day shapes.

The International Annex I came first. The Inland Annex I is very similar but many specifications differ to suit the particular conditions of the inland waterways.

The Inland Annex I is a regulation. It is marked with "section" symbols (§) and numbers beginning with "84," because it is Part 84, Title 33 of the Code of Federal Regulations. The other four Inland annexes are Parts 85, 86, 87, and 88.


INTERNATIONAL

INLAND

1. Definition

The term "height above the hull" means height above the uppermost continuous deck. This height shall be measured from the position vertically beneath the location of the light.

§ 84.01 Definitions

(a) The term "height above the hull" means height above the uppermost continuous deck. This height shall be measured from the position vertically beneath the location of the light.

 

Annex I normally expresses the vertical position of lights as "height above the hull." This is measured from the highest deck (directly below the light, in the center of the vessel if the light is in the center) that extends over the length of the ship or nearly so.


INLAND

(b) High-speed craft means a craft capable of maximum speed in meters per second (m/s) equal to or exceeding:

 

This definition of high-speed craft has been added because of an exception for this class of vessel to the general masthead light vertical positioning requirements. The definition was taken from the International Maritime Organization's "International Code of Safety for High-Speed Craft."


INLAND

(c) The term "practical cut-off" means, for vessels 20 meters or more in length, 12.5 percent of the minimum luminous intensity (Table 84.15(b)) corresponding to the greatest range of visibility for which the requirements of Annex I are met.

 

Many navigation lights give you a rough idea of the orientation of a vessel, depending on whether you see a green sidelight, a red sidelight, masthead lights, or whatever. In other words, you know that, in relation to the observed vessel, you are within a certain horizontal sector. The term "horizontal sector" refers to the arc around the horizon through which each navigation light is supposed to shine. When you move from the inside to the outside of the sector, the light "cuts off."

In theory, a light should have full intensity everywhere inside the sector and be absolutely dark outside the sector. In practice, this level of performance hasn't been achieved using common technology and at a reasonable cost. Cut-off isn't instant and complete. Some light, undesirably because it affects perceptions of orientation, leaks outside of the sector. Annex I requires that "practical cut-off" be a reduction of the light intensity down to below 12.5 percent of what must be shown inside the sector. This is for lights designed for vessels twenty meters and longer.

The term "practical cut-off" is defined only in Inland Annex I, but the U.S. Coast Guard is using the same definition in its International Rules navigation light approval program for inspected vessels. The United States does not define practical cut-off for lights designed for vessels less than twenty meters, although a number of European countries do. These countries also certify or approve their own small-vessel navigation lights as meeting the International Annex I specifications.

The Inland Rule definition for practical cut-off is worded so that a navigation light may be used on a vessel smaller than the vessel size class for which it was designed. The language "corresponding to the greatest range of visibility for which the requirements of Annex I are met" results in a single practical cut-off for any particular light rather than a different practical cut-off for each class of vessel.

For example, a masthead light designed for vessels twenty to fifty meters long has a minimum required range of five miles (see Rule 22). Annex I requires an intensity of at least fifty-two candelas for a five-mile light (see § 84.15). A six-mile light needs ninety-four candelas, almost twice as bright; a three-mile light, twelve candelas. We'll say in our example that the actual "five-mile" light has an intensity of sixty-three candelas in the sector and is being used on a boat eighteen meters long. The practical cut-off in this case would be 12.5 percent of fifty-two candelas or 6.5. We don't base practical cut-off on the sixty-three candela actual intensity or on the twelve-candela minimum required intensity for the size vessel (eighteen meters) on which the light is installed.


INLAND

(d) The term "Rule" or "Rules" means the Inland Navigation Rules contained in Sec. 2 of the Inland Navigational Rules Act of 1980 (Pub. L. 96-591, 94 Stat. 3415, 33 U.S.C. 2001, December 24, 1980) as amended.

 

The Inland navigation rules were enacted by Congress through legislation, whereas the annexes were enacted by the Coast Guard as regulations.


INTERNATIONAL

INLAND

2. Vertical positioning and spacing of lights

(a) On a power-driven vessel of 20 meters or more in length the masthead lights shall be placed as follows:

(i) the forward masthead light, or if only one masthead light is carried, then that light, at a height above the hull of not less than 6 meters, and, if the breadth of the vessel exceeds 6 meters, then at a height above the hull not less than such breadth, so however that the light need not be placed at a greater height above the hull than 12 meters.

(ii) when two masthead lights are carried the after one shall be at least 4.5 meters vertically higher than the forward one.

(b) The vertical separation of masthead lights of power-driven vessels shall be such that in all normal conditions of trim the after light will be seen over and separate from the forward light at a distance of 1000 meters from the stem when viewed from sea level.

§ 84.03 Vertical positioning and spacing of lights

(a) On a power-driven vessel of 20 meters or more in length the masthead lights shall be placed as follows:

(1) The forward masthead light, or if only one masthead light is carried, then that light, at a height above the hull of not less than 5 meters, and, if the breadth of the vessel exceeds 5 meters, then at a height above the hull not less than such breadth, so however that the light need not be placed at a greater height above the hull than 8 meters.

(2) When two masthead lights are carried the after one shall be at least 2 meters vertically higher than the forward one.

(b) The vertical separation of masthead lights of power-driven vessels shall be such that in all normal conditions of trim the after light will be seen over and separate from the forward light at a distance of 1000 meters from the stem when viewed from sea level.

 


(c) The masthead light of a power-driven vessel of 12 meters but less than 20 meters in length shall be placed at a height above the gunwale of not less than 2.5 meters.

(d) A power-driven vessel of less than 12 meters in length may carry the uppermost light at a height of less than 2.5 meters above the gunwale. When however, a masthead light is carried in addition to sidelights and a sternlight or the all-round light prescribed in rule 23(c)(i) is carried in addition to sidelights, then such masthead light or all-round light shall be carried at least 1 meter higher than the sidelights.

(c) The masthead light of a power-driven vessel of 12 meters but less than 20 meters in length shall be placed at a height above the gunwale of not less than 2.5 meters.

(d) The masthead light, or the all-round light described in Rule 23(c), of a power-driven vessel of less than 12 meters in length shall be carried at least 1 meter higher than the sidelights.

 

Under International Rule 23, power-driven vessels less than twelve meters long may display the following: (1) sidelights, masthead light, and sternlight; (2) sidelights and all-round light; or (3) an all-round light, depending on boat size, speed, and preference of builder or owner. The Inland Rules permit only the first two options.

If sidelights are displayed, the masthead light or all-round light must be at least one meter above the sidelights. The vertical separation is measured at operating trim, which is often different from static trim. Because boat trim may change significantly with speed changes, vertical separation may be decreased substantially (from what deckline-to-light measurement would indicate) if the masthead/all-round light is mounted very far aft of the sidelights.

This is especially a problem if the all-round light is mounted all the way aft, as was required by the now-repealed Motorboat Act of 1940, and the sidelights are mounted all the way forward. The all-round light (or masthead light) may now be mounted anywhere from stem to stern. Mounting it horizontally close to the sidelights will minimize the adverse effect or trim changes on vertical separation.


INTERNATIONAL

INLAND

(e) One of the two or three masthead lights prescribed for a power-driven vessel when engaged in towing or pushing another vessel shall be placed in the same position as either the forward masthead light or the after masthead light; provided that if carried on the aftermast, the lowest after masthead light shall be at least 4.5 meters vertically higher than the forward masthead light.

(e) One of the two or three masthead lights prescribed for a power-driven vessel when engaged in towing or pushing another vessel shall be placed in the same position as either the forward masthead light or the after masthead light, provided that if carried on the aftermast, the lowest after masthead light shall be at least 2 meters vertically higher than the highest forward masthead light.

 

In most cases, vessels engaged in towing display either one or two masthead lights in addition to the normal one(s) prescribed for ordinary power-driven vessels (see Rules 23 and 24). Although the language in the Rules says two (or three) masthead lights "instead of" an ordinary masthead light, Annex I 2(e)/§ 84.03(e) makes clear that the Rule 23 masthead light is to be one of the two or three in a vertical column, and paragraph (f)(i) says that of the two or three masthead lights carried in a vertical line for towing, the Rule 23 masthead light must be the highest one.

Vessels fifty meters or longer must carry both forward and after masthead lights (smaller vessels may do so). Vessels carrying both forward and after masthead lights (Rule 23(a)) also carry forward and after masthead lights when towing (Rule 24(d)). For towing, the additional masthead lights (one, or two if the tow length exceeds two hundred meters) can be carried under either the forward masthead light or the after masthead light.

If carried under the forward masthead light, the vertical separation between forward and after masthead lights will be unchanged from the non-towing display. If the additional lights are carried under the after masthead light, the vertical separation between masthead lights on forward and after masts will be reduced.

Annex I 2(e)/§ 84.03(e) requires that at least the minimum vertical separation be maintained between the lowest after masthead light and the forward masthead light.

Thus, if you carry your additional masthead lights on the after mast, your ordinary Rule 23 after masthead light must be mounted higher than would otherwise be required by Annex I 2(a)(ii)/§ 84.03(a)(2). The minimum vertical separation differs between the International (4.5 meters) and Inland (2 meters) Rules.


INTERNATIONAL

INLAND

(f)(i) The masthead light or lights prescribed in Rule 23(a) shall be so placed as to be above and clear of all other lights and obstructions except as described in subparagraph (ii).

(ii) When it is impracticable to carry the all-round lights prescribed by Rule 27(b)(i) or Rule 28 below the masthead lights, they may be carried above the after masthead light(s) or vertically in between the forward masthead light(s) and after masthead light(s), provided that in the latter case the requirement of Section 3(c) of this Annex shall be complied with.

(f)(1) The masthead light or lights prescribed in Rule 23(a) shall be so placed as to be above and clear of all other lights and obstructions except as described in paragraph (f)(2) of this section.

(2) When it is impracticable to carry the all-round lights prescribed by Rule 27(b)(i) below the masthead lights, they may be carried above the after masthead light(s) or vertically in between the forward masthead light(s) and after masthead light(s), provided that in the latter case the requirement of § 84.05(d) shall be complied with.

 

The Rule 23 masthead lights are considered to be of great importance. As the brightest lights, they function as the reference by which other navigation lights are evaluated. Annex I 2(f)/§ 84.03(f) therefore requires that they be mounted high and be unobstructed.

The exception was added after problems were experienced with all-round lights, which are difficult to see "all-round" if they are mounted below a structure holding up the masthead light. All-round lights may now be placed above masthead lights, but only in the fashion described, which is designed to minimize interference from the masthead lights.

The exempted all-round lights are those for vessels restricted in ability to maneuver (Rule 17(b)(i)) and for vessels constrained by draft (Rule 28, International only).

When all-round lights are above the after masthead light, they are usually directly above, not because it is required but because it is practical.

The all-round lights can be mounted on a mast or hung from a yardarm.

The exception permitting display of all-round lights above masthead lights applies only when it is not practicable to mount the all-round lights below the masthead light(s). If practicable, it must be done.


INTERNATIONAL

INLAND

(g) The sidelights of a power-driven vessel shall be placed at a height above the hull not greater than three quarters of that of the forward masthead light. They shall not be so low as to be interfered with by deck lights.

(g) The sidelights of a power-driven vessel shall be placed at least one meter lower than the forward masthead light. They shall not be so low as to be interfered with by deck lights.

 

The Requirement in the International version of this paragrph is modified or supplemented by paragraphs 2(d) and 2(h) of Annex I for vessels less than twelve and twenty meters, respectively.


INTERNATIONAL

INLAND

(h) The sidelights, if in a combination lantern and carried on a power-driven vessel of less than 20 meters in length, shall be placed not less than 1 meter below the masthead light.

(h) [Reserved]

 

Only the International version has a paragraph (h). A similar Inland requirement would have duplicated the Inland § 84.03(g) requirement. Inland paragraph (h) was reserved so that corresponding International/Inland paragraphs would be numbered (or lettered) the same.


INTERNATIONAL

INLAND

(i) When the Rules prescribe two or three lights to be carried in a vertical line, they shall be spaced as follows;

(i) on a vessel of 20 meters in length or more such lights shall be spaced not less than 2 meters apart, and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than 4 meters above the hull;

(ii) on a vessel of less than 20 meters in length such lights shall be spaced not less than 1 meter apart and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than 2 meters above the gunwale;

(iii) when three lights are carried they shall be equally spaced.

(i) When the Rules prescribe two or three lights to be carried in a vertical line, they shall be spaced as follows;

(1) On a vessel of 20 meters in length or more such lights shall be spaced not less than 1 meter apart, and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than 4 meters above the hull;

(2) On a vessel of less than 20 meters in length such lights shall be spaced not less than 1 meter apart and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than 2 meters above the gunwale;

(3) When three lights are carried they shall be equally spaced.

 

The navigation rules frequently require the display of two or three lights in a vertical line--all-round lights, masthead lights, or lights aimed aft for towing. Annex I prescribes the spacing between the lights and the height above the hull (above the gunwale for smaller vessels) for the lowest light. Vertical height above the "hull" is above the uppermost continuous deck.

When a yellow towing light is displayed above the sternlight or above another towing light, the height-above-the-hull requirements do not apply. The sternlight, of course, is the same one used when not towing and may be placed right on the uppermost continuous deck or even below it. The same principle operates when two towing lights (no sternlight) are displayed in a vertical line (Inland Rules only).


INTERNATIONAL

INLAND

(j) The lower of the two all-round lights prescribed for a vessel when engaged in fishing shall be at a height above the sidelights not less than twice the distance between the two vertical lights.

(k) The forward anchor light prescribed in Rule 30(a)(i), when two are carried, shall not be less than 4.5 meters above the after one. On a vessel 50 meters or more in length this forward anchor light shall be placed at a height of not less than 6 meters above the hull.

(j) The lower of the two all-round lights prescribed for a vessel when engaged in fishing shall be at a height above the sidelights not less than twice the distance between the two vertical lights.

(k) The forward anchor light prescribed in Rule 30(a)(i), when two are carried, shall not be less than 4.5 meters above the after one. On a vessel 50 meters or more in length this forward anchor light shall be placed at a height of not less than 6 meters above the hull.

 

Rule 30 requires two anchor lights for vessels fifty meters or longer. Smaller vessels may display two anchor lights but are required to display only one (where it can best be seen).


INTERNATIONAL

INLAND

3. Horizontal positioning and spacing of lights

(a) When two masthead lights are prescribed for a power-driven vessel, the horizontal distance between them shall not be less than one half of the length of the vessel but need not be more than 100 meters. The forward light shall be placed not more than one quarter of the length of the vessel from the stem.

§ 84.05 Horizontal positioning and spacing of lights

(a) Except as specified in paragraph (e) of this section, when two masthead lights are prescribed for a power-driven vessel, the horizontal distance between them shall not be less than one-quarter of the length of the vessel but need not be more than 50 meters. The forward light shall be placed not more than one half of the length of the vessel from the stem.

 

This provision affects primarily vessels fifty meters or longer because smaller vessels do not have to display both forward and after masthead lights. Both the International and Inland minimum separation is based on the length of the vessel. For power-driven vessels two hundred meters or longer, the minimum horizontal separation is a flat one hundred meters for International and fifty meters for Inland.


INTERNATIONAL

INLAND

(b) On a power-driven vessel of 20 meters or more in length the sidelights shall not be placed in front of the forward masthead lights. They shall be placed at or near the side of the vessel.

(c) When the lights prescribed in 27(b)(i) or Rule 28 are placed vertically between the forward masthead light(s) and the after masthead light(s) these all-round lights shall be placed at a horizontal distance of not less than 2 meters from the fore and aft centerline of the vessel in the athwartship direction.

(b) On a power-driven vessel of 20 meters or more in length the sidelights shall not be placed in front of the forward masthead lights. They shall be placed at or near the side of the vessel.

(c) When the lights prescribed in 27(b)(i) are placed vertically between the forward masthead light(s) and the after masthead light(s) these all-round lights shall be placed at a horizontal distance of not less than 2 meters from the fore and aft centerline of the vessel in the athwartship direction.

 

This provision is linked with Annex I (2)(f)/§ 84.03(f) requirement and is illustrated with the discussion of that vertical-positioning requirement.


INTERNATIONAL

INLAND

(d) When only one masthead light is prescribed for a power-driven vessel, this light shall be exhibited forward of amidships; except that a vessel of less than 20 meters in length need not exhibit this light forward of amidships but shall exhibit it as far forward as is practicable.

(d) When only one masthead light is prescribed for a power-driven vessel, this light must be exhibited forward of amidships. For a vessel of less than 20 meters in length, the vessel shall exhibit one masthead light as far forward as is practicable.

(e) On power-driven vessels 50 meters but less than 60 meters in length operated on Western Rivers, the horizontal distance between masthead lights shall not be less than 10 meters.

 

Western Rivers towboats fifty to sixty meters long have a slightly relaxed requirement because their typical house arrangement makes meeting the full one-quarter-length separation more costly.


INTERNATIONAL

INLAND

4. Details of location of direction-indicating lights for fishing vessels, dredgers and vessels engaged in underwater operations

(a) The light indicating the direction of the outlying gear from a vessel engaged in fishing as prescribed in Rule 26(c)(ii) shall be placed at a horizontal distance of not less than 2 meters and not more than 6 meters away from the two all-round red and white lights. This light shall be placed not higher than the all-round white light prescribed in Rule 26(c)(i) and not lower than the sidelights.

§ 84.07 Details of location of direction-indicating lights for fishing vessels, dredgers and vessels engaged in underwater operations

(a) The light indicating the direction of the outlying gear from a vessel engaged in fishing as prescribed in Rule 26(c)(ii) shall be placed at a horizontal distance of not less than 2 meters and not more than 6 meters away from the two all-round red and white lights. This light shall be placed not higher than the all-round white light prescribed in Rule 26(c)(i) and not lower than the sidelights.

 

Rule 26(c) applies to vessels engaged in fishing by means other than trawling. The identifying lights are an all-round red in a vertical line over an all-round white. When outlying fishing gear extends more than 150 meters from the vessel, an all-round white light must be displayed in the direction of that gear. This all-round light must be outside a circle with a two-meter radius and inside a circle with a six-meter radius, as viewed from above the vessel and with the center of both circles at the vertical line running through the red and white all-round identifying lights.


INTERNATIONAL

INLAND

(b) The lights and shapes on a vessel engaged in dredging or underwater operations to indicate the obstructed side and/or the side on which it is safe to pass, as prescribed in Rule 27(d)(i) and (ii), shall be placed at the maximum practical horizontal distance, but in no case less than 2 meters, from the lights or shapes prescribed in Rule 27(b)(i) and (ii). In no case shall the upper of these lights or shapes be at a greater height than the lower of the three lights or shapes prescribed in Rule 27(b)(i) and (ii).

(b) The lights and shapes on a vessel engaged in dredging or underwater operations to indicate the obstructed side and/or the side on which it is safe to pass, as prescribed in Rule 27(d)(i) and (ii), shall be placed at the maximum practical horizontal distance, but in no case less than 2 meters, from the lights or shapes prescribed in Rule 27(b)(i) and (ii). In no case shall the upper of these lights or shapes be at a greater height than the lower of the three lights or shapes prescribed in Rule 27(b)(i) and (ii).

 

Rule 27(d) applies to vessels engaged in dredging or underwater operations when their work involves placing an obstruction to one side of the vessel. The vessel displays the 27(b) red-white-red vertical array to indicate restricted ability to maneuver, the 27(d) red-over-red all-round lights to indicate the side having the obstruction, and green-over-green all-round lights to indicate on which side it is safe to pass.

These Annex I provisions also apply to the corresponding shapes during the day.

Annex I continues - Click Here

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Annex II