Rule 28 – Explained

Part C · Lights and shapes · Rule 28

Vessels constrained by their draught

28 A vessel constrained by her draught may, in addition to the lights prescribed for power-driven vessels in Rule 23, exhibit where they can best be seen three all-round red lights in a vertical line, or a cylinder.

“A vessel constrained by her draught”Rule 3(h): a power-driven vessel which, because of her draught 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. Both depth and width count: for example, a deep-draught tanker in a dredged channel, with shallow water either side.
“may, in addition to the lights prescribed for power-driven vessels in Rule 23”The signals are optional (“may”). If she shows them, they are in addition to her normal power-driven vessel lights: masthead light(s), sidelights and sternlight. Only a power-driven vessel can be constrained by her draught.
“exhibit where they can best be seen three all-round red lights in a vertical line”At night, three all-round red lights, one above the other, where other vessels can see them most easily.
“or a cylinder”By day, a black cylinder, at least 0.6 metre in diameter and twice as tall as it is wide (Annex I section 6(a)).

Three reds or a cylinder: she can’t leave her channel. Under Rule 18(d), every vessel except one not under command or restricted in her ability to manoeuvre must, if the circumstances admit, avoid impeding her safe passage when she shows these signals. She, in turn, must navigate with particular caution.

Vessel constrained by her draught, less than 50m

Vessel constrained by her draught, Bow aspect, Less than 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtBow aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Bow aspect, Less than 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtBow aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Port aspect, Less than 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtPort aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Port aspect, Less than 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtPort aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Starboard aspect, Less than 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtStarboard aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Starboard aspect, Less than 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtStarboard aspectLess than 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Stern aspect, Unknown length, Underway, possibly making way – day — Vessel constrained by her draughtStern aspectUnknown lengthUnderway, possibly making way

Vessel constrained by her draught, Stern aspect, Unknown length, Underway, possibly making way – night — Vessel constrained by her draughtStern aspectUnknown lengthUnderway, possibly making way

Vessel constrained by her draught, probably over 50m

Vessel constrained by her draught, Bow aspect, Probably over 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtBow aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Bow aspect, Probably over 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtBow aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Port aspect, Probably over 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtPort aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Port aspect, Probably over 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtPort aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Starboard aspect, Probably over 50m in length, Underway, possibly making way – day — Vessel constrained by her draughtStarboard aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught, Starboard aspect, Probably over 50m in length, Underway, possibly making way – night — Vessel constrained by her draughtStarboard aspectProbably over 50m in lengthUnderway, possibly making way

Vessel constrained by her draught – Day shapes

Vessel constrained by her draught, Bow aspect, Unknown length, Underway, possibly making way – day — Vessel constrained by her draughtBow aspectUnknown lengthUnderway, possibly making way

Vessel constrained by her draught, Port aspect, Unknown length, Underway, possibly making way – day — Vessel constrained by her draughtPort aspectUnknown lengthUnderway, possibly making way

Vessel constrained by her draught, Starboard aspect, Unknown length, Underway, possibly making way – day — Vessel constrained by her draughtStarboard aspectUnknown lengthUnderway, possibly making way