Official rule text as published in the U.S. Coast Guard Navigation Rules
| International | Inland |
|---|
(d)(i) 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.
(ii) A vessel constrained by her draft shall navigate with particular caution having full regard to her special condition. | (d) Reserved. |
MyCOLREGS explanation
Summary
Under Rule 18(d), which vessel owes deference to a vessel constrained by her draft depends on where you are. Internationally, any vessel other than one not under command or restricted in ability to maneuver must, where circumstances allow, avoid impeding a draft-constrained vessel that is showing the Rule 28 signals, and that vessel must navigate with particular caution. On U.S. inland waters, this subsection is simply reserved - there is no equivalent inland provision, so the extra deference to a draft-constrained vessel comes from ordinary good seamanship and narrow-channel duties rather than from a matching Rule 18(d).
Real World Example
This is one of the few places where the Rule itself changes underfoot: the same loaded tanker gets explicit extra deference under Rule 18(d) on the high seas, but the moment she's in U.S. inland waters that subsection is deliberately left blank, so any added caution around her has to come from ordinary seamanship rather than this specific rule. A small-boat operator who assumes the international deference always applies could end up crowding a ship that Rule 18(d) itself no longer obligates anyone to avoid.
Practice Questions
Q1. A small recreational boat is crossing a dredged channel where a loaded cargo ship, constrained by her draft and displaying the Rule 28 signals, has almost no room to leave the channel. On the high seas / international waters, what does Rule 18(d) require of the small boat?
A. Nothing - Rule 18(d) only applies to vessels not under command.
B. She must hold her course and speed no matter what.
C. She must, if circumstances admit, avoid impeding the draft-constrained vessel's safe passage.
D. She must sound the danger signal and stop engines.
Q2. The same encounter happens instead on U.S. inland waters. What does Rule 18(d) itself say about the small boat's duty toward the draft-constrained ship?
A. Inland Rule 18(d) only applies to vessels over 100 meters.
B. Inland Rule 18(d) requires the ship to keep clear of the small boat instead.
C. The same as international waters, word for word.
D. Rule 18(d) is reserved on inland waters - it contains no counterpart provision.
Practice Question Answers
Q1.
C. She must, if circumstances admit, avoid impeding the draft-constrained vessel's safe passage. The International wording of Rule 18(d)(i) requires any vessel other than one not under command or restricted in ability to maneuver to avoid impeding a vessel constrained by her draft that is exhibiting the Rule 28 signals, where circumstances allow. A confuses constrained-by-draft with a different status entirely. B treats the small boat's duty as absolute regardless of circumstances, when the rule qualifies it with "if circumstances admit." D jumps to a specific maneuver the rule doesn't prescribe.
Q2.
D. Rule 18(d) is reserved on inland waters - it contains no counterpart provision. The Inland version of Rule 18(d) is explicitly marked "Reserved" - there is no inland rule paralleling the international constrained-by-draft deference duty, so any extra caution around a draft-constrained vessel inland comes from other rules and ordinary seamanship. A invents a size limit. B reverses the obligation entirely. C assumes the inland rule mirrors the international one word-for-word, when in fact the inland version leaves this position reserved with no counterpart provision.