Constrained by Draft: The Rule 28 Lights and Shape

What the rule requires

A vessel constrained by her draft may exhibit, where they can best be seen, three all-round red lights in a vertical line, or a cylinder by day, in addition to the lights prescribed for power-driven vessels in Rule 23 COLREGs Rule 28. Three reds, vertical, all-round. The cylinder is the only day shape the rule names, and the illustration accompanying the rule shows the arrangement on a vessel of 50 metres or greater in length, underway; the rule text itself attaches no length threshold to the signal.

Two features of that sentence decide questions.

The first is may. Rule 28 is permissive. A deep-draft ship threading a dredged channel is under no obligation to light up as constrained by her draft, and the absence of three red lights tells you nothing about whether she is in fact hemmed in by the bottom. Distractors are built on the word "shall."

The second is in addition to. The three reds are carried on top of her normal power-driven vessel lights, not instead of them. She is still a power-driven vessel and still shows what a power-driven vessel shows.

Now the status itself. A vessel constrained by her draft is a power-driven vessel which, because of her draft in relation to the available depth and width of navigable water, is severely restricted in her ability to deviate from the course she is following COLREGs Rule 3(h). Four triggers sit in that definition, and every one of them has been used to build a wrong answer:

• Power-driven. Nothing else qualifies. A sailing vessel — one under sail with her propelling machinery, if fitted, not in use COLREGs Rule 3(c) — cannot be constrained by her draft no matter how deep she floats.
• **Depth and width.** The definition is not about draft against charted depth alone. A vessel with plenty of water under the keel but no room to swing either side of the channel axis is squarely inside the definition.
• Severely restricted. Inconvenience is not the test. Reduced options are not the test.
• Deviate from the course she is following. The constraint is on altering course, not on stopping, sounding signals or anything else.

She is not at anchor, made fast to the shore, or aground — that is, she is underway COLREGs Rule 3(i) — because the constraint is expressed as an inability to leave the course she is following.

What the display buys her

Less than candidates expect. Any vessel other than a vessel not under command or a vessel restricted in her ability to maneuver shall, if the circumstances of the case admit, avoid impeding the safe passage of a vessel constrained by her draft exhibiting the signals in Rule 28; and the constrained vessel herself shall navigate with particular caution having full regard to her special condition COLREGs Rule 18(d).

Read the three qualifiers. Avoid impeding is a weaker duty than keep out of the way, which is the phrase Rule 18 uses for a power-driven vessel's obligation toward a vessel not under command, a vessel restricted in her ability to maneuver, a vessel engaged in fishing and a sailing vessel COLREGs Rule 18. If the circumstances of the case admit is a further softening. And the duty is tied to her exhibiting the signals — the whole of Rule 18(d) hangs off that display.

Two classes are cut out of the duty by name: a vessel not under command and a vessel restricted in her ability to maneuver owe a constrained-by-draft vessel nothing under Rule 18(d).

You are underway at night on a power-driven vessel in international waters and sight three all-round red lights in a vertical line ahead. Are you required to keep out of her way?

No. Rule 18(a) lists the vessels a power-driven vessel must keep out of the way of, and a vessel constrained by her draft is not among them. Your duty is the lesser one in Rule 18(d)(i): avoid impeding her safe passage, if the circumstances of the case admit. She remains a power-driven vessel, so if you are crossing or meeting, the ordinary steering and sailing rules for two power-driven vessels still govern the geometry.

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Telling it apart

Constrained by draft, not under command and restricted in her ability to maneuver all describe a vessel that cannot readily get out of your way, and the exam mixes them deliberately. The single criterion is the source of the restriction.

• Vessel constrained by her draft — the restriction comes from the water: her draft against the available depth and width, leaving her severely restricted in deviating from her course COLREGs Rule 3(h). She must be power-driven. Most often misfiled: candidates apply this status on inland waters, where it does not exist.
• Vessel not under command — the restriction comes from some exceptional circumstance, which makes her unable to maneuver as the Rules require and therefore unable to keep out of the way COLREGs Rule 3(f). The circumstance is a casualty, not a job. Most often misfiled: a vessel that has stopped on purpose is put in this class.
• Vessel restricted in her ability to maneuver — the restriction comes from the nature of her work, and the rule gives a non-exhaustive list: laying, servicing or picking up a navigation mark, submarine cable or pipeline; dredging, surveying or underwater operations; replenishment or transferring persons, provisions or cargo while underway; launching or recovery of aircraft; mine clearance; and a towing operation such as severely restricts the towing vessel and her tow in deviating from their course COLREGs Rule 3(g). Most often misfiled: that last entry. A tow so severe as to restrict deviation is restricted in her ability to maneuver — not constrained by her draft, even in shallow water.

The distinction is worth real money on the Rule 18 questions, because these three classes sit in different places in the responsibilities and are owed different duties.

The pecking order, and where it lies to you

The common mnemonic is "New Reels Catch Fish So Purchase Some" — Not under command, Restricted in ability to maneuver, Constrained by draft, Fishing, Sailing, Power-driven, Seaplane. Learn it; it is the device in circulation and it puts the classes in the right sequence.

Then correct it in three places, because as a flat ladder it is wrong about this topic specifically:

1. C is International only. Delete that rung entirely for an Inland question COLREGs Rule 28.
2. The rungs are not all the same kind of duty. Rule 18 says keep out of the way down the top of the ladder, but only avoid impeding, if the circumstances of the case admit for constrained by draft, and so far as possible, keep out of the way for a vessel engaged in fishing toward a vessel not under command or restricted in her ability to maneuver COLREGs Rule 18.
3. The ladder does not run all the way up for C. Not under command and restricted in her ability to maneuver are exempted from the constrained-by-draft duty by name COLREGs Rule 18(d).

The whole of Rule 18 is prefaced "Except where Rules 9, 10 and 13 otherwise require," so the ladder is subordinate to those three rules wherever they bite.

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Working a question

You are on a 62-foot power-driven charter vessel, underway in the approaches to a major port on the high seas side of the demarcation line, at night. Dead ahead and slightly to starboard you make out three all-round red lights in a vertical line, above sidelights and masthead lights on a large ship. She is inbound on the dredged channel; you are crossing it. What are you required to do?

1. Establish the regime. High seas side of the demarcation line means International. Had this been an Inland question, three all-round red lights in a vertical line could not be a constrained-by-draft signal at all, because Inland Rule 28 is [Reserved] COLREGs Rule 28.
2. Identify the vessel. Three all-round reds, vertical, carried in addition to power-driven vessel lights: a vessel constrained by her draft. She has exhibited the signals in Rule 28, which is the condition that activates the duty in Rule 18(d).
3. Fix her class. She is a power-driven vessel — that is inside the definition itself COLREGs Rule 3(h). You have not lost the ordinary crossing situation between two power-driven vessels; you have gained an additional obligation on top of it.
4. Fix your own status. You are neither not under command nor restricted in her ability to maneuver, so you are one of the vessels caught by "any vessel other than" COLREGs Rule 18(d).
5. State the duty in the rule's words. Avoid impeding her safe passage, if the circumstances of the case admit. Not "keep out of the way," and not "stand on and hold your course."
6. Convert it to an action. Take your action early and large enough that she never has to deviate from the course she is following, since deviating is the thing she is severely restricted in doing. Passing astern of her achieves that; crossing ahead on the assumption she will slow does not.

The candidate who loses this question is the one who reaches step 5 with a general sense that the big ship has priority and then selects the option worded "keep clear" or "give way." The rule's words are the discriminator.

Same situation, except you are a vessel restricted in her ability to maneuver, dredging in the channel edge. Does the answer change?

Yes. Rule 18(d)(i) applies to "any vessel other than a vessel not under command or a vessel restricted in her ability to maneuver." You are exempt from the duty to avoid impeding her. She, for her part, shall navigate with particular caution having full regard to her special condition, and under Rule 18(a)(ii) a power-driven vessel underway — which she is — shall keep out of the way of a vessel restricted in her ability to maneuver.

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Where candidates lose the point

Answering "keep out of the way" for a constrained-by-draft vessel. The phrase is everywhere else in Rule 18, so it feels right. The rule gives constrained by draft only "avoid impeding the safe passage," qualified by "if the circumstances of the case admit."

Choosing "Both International & Inland." Three red lights look like a fundamental signal, and the candidate has never had reason to doubt it. Inland Rule 28 is [Reserved]. Any inland-labelled question about constrained-by-draft lights, shapes or privileges resolves against the status existing at all.

Reading "shall exhibit." Rule 28 says may. A vessel that qualifies under Rule 3(h) and shows nothing has broken no rule, and the Rule 18(d) duty owed to her is expressed as owed to a vessel "exhibiting the signals in Rule 28."

Making a sailing vessel or a tug and tow constrained by her draft. Deep draft plus a narrow channel sounds sufficient. The definition opens with "power-driven vessel," which excludes a sailing vessel outright, and a towing operation that severely restricts deviation is named in Rule 3(g) as restricted in her ability to maneuver.

Testing draft against depth only. "Available depth and width" — a ship with six feet under the keel and a channel two cables wide can still be outside the definition; one with room below but no room beside can be inside it.

Assuming a vessel not under command must keep clear of her. She outranks the constrained vessel in the mnemonic, and the mnemonic reads like a one-way ladder. Rule 18(d)(i) names both not under command and restricted in her ability to maneuver as excluded from the duty.

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Check yourself

(INTERNATIONAL ONLY) You sight, in addition to her running lights, three all-round red lights in a vertical line on a vessel dead ahead. What is she?

A vessel constrained by her draft. Three all-round red lights in a vertical line, exhibited in addition to the lights prescribed for power-driven vessels in Rule 23, is the Rule 28 signal. Her day equivalent is a cylinder.

You are on a sailing vessel, engine off, drawing 14 feet in a narrow buoyed channel with 15 feet of charted depth, and you cannot leave the channel. May you exhibit three all-round red lights?

No. Rule 3(h) defines a vessel constrained by her draft as a power-driven vessel. A vessel under sail with propelling machinery not in use is a sailing vessel under Rule 3(c), and the status is closed to her regardless of the water she is in.

(INLAND ONLY) A vessel in a dredged channel on inland waters is severely restricted by her draft. What lights or shapes does she exhibit to indicate that condition?

None. Inland Rule 28 is [Reserved] — there is no constrained-by-draft status, signal or privilege on inland waters. If an inland-labelled option offers three red lights or a cylinder for this condition, it is a distractor.

(INTERNATIONAL ONLY) A vessel constrained by her draft, showing her Rule 28 lights, is approaching a vessel engaged in fishing with nets that restrict her maneuverability. What is the fishing vessel required to do?

Avoid impeding the safe passage of the constrained vessel, if the circumstances of the case admit. Rule 18(d)(i) applies to any vessel other than one not under command or one restricted in her ability to maneuver, and a vessel engaged in fishing — defined in Rule 3(d) by fishing apparatus that restricts maneuverability — is neither of those.

Your vessel has lost steering following a rudder casualty and cannot maneuver as the Rules require. A vessel constrained by her draft is closing on your starboard bow, showing three all-round reds. What do the Rules require of you toward her?

Nothing under Rule 18(d). You answer the definition of a vessel not under command in Rule 3(f) — unable to maneuver through some exceptional circumstance — and Rule 18(d)(i) excludes a vessel not under command from the duty to avoid impeding a vessel constrained by her draft. She is the one required to navigate with particular caution having full regard to her special condition.

(INTERNATIONAL ONLY) A deep-draft ship in a channel is not displaying three all-round red lights. Is she therefore not constrained by her draft, and does she owe you a duty as an ordinary power-driven vessel?

Rule 28 says a vessel constrained by her draft may exhibit the signals, so their absence does not settle her condition. What it does settle is the duty in Rule 18(d)(i), which is expressed toward a vessel "exhibiting the signals in Rule 28." She remains a power-driven vessel, and the responsibilities between two power-driven vessels under Rule 18 and the steering and sailing rules apply normally.

Which is the correct classification: a vessel transferring cargo to another vessel while underway, in a channel where her draft leaves little water beneath her?

Restricted in her ability to maneuver. Rule 3(g) lists a vessel engaged in replenishment or transferring persons, provisions or cargo while underway. The restriction arises from the nature of her work, and that is the criterion — the draft is incidental. Under Rule 18(a)(ii) a power-driven vessel underway shall keep out of her way, a stronger duty than the one owed to a vessel constrained by her draft.