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Rule 28 · USCG Navigation Rules

Vessel constrained by her draught (CBD)

50 m +International only

A deep-draught ship that cannot leave the channel may add three all-round red lights (cylinder by day) to her power-driven lights — International Rules only.

Viewpoint

Display

Drag to orbit freely, scroll or pinch to zoom — or use the viewpoint buttons above (keyboard friendly).

From the port bow you see:

  • white — After masthead light (higher)
  • All-round red (top)
  • All-round red (middle)
  • white — Forward masthead light (lower)
  • All-round red (bottom)
  • red — Port sidelight

→ Vessel constrained by her draught (CBD) — Underway (may exhibit), seen from the port bow.

International Rules onlyapplies to your current setting

Constrained by draught does NOT exist under the US Inland Rules — Inland Rule 28 is reserved. On US inland waters such a ship is lit and ranked simply as a power-driven vessel.

Choose International or Inland in language and regional settings in the site header.

Memory aid

“Three reds in a row: this channel is my bed — I physically cannot get out of your way.”

What it means

Underway (may exhibit)

The three reds and cylinder are optional ('may exhibit') and come IN ADDITION to normal power-driven lights — here a 50 m+ ship with both masthead lights.

Day shapes

  • Day shape: Cylinder

    Cylinder

    One cylinder where it can best be seen — the only cylinder in the rules.

Light details

LightColourArcPosition
All-round red (top)red360° all-roundMast, vertical line (top)
All-round red (middle)red360° all-roundMast, vertical line (2nd from top)
All-round red (bottom)red360° all-roundMast, vertical line (3rd from top)
Forward masthead light (lower)white225° forwardForward masthead position
After masthead light (higher)white225° forwardAft masthead position, higher
Port sidelightred112.5° to portPort side, deck level
Starboard sidelightgreen112.5° to starboardStarboard side, deck level
Sternlightwhite135° aftStern

2D profile

Labelled side view — works without WebGL and in print. Variant shown: Underway (may exhibit).

Light profile seen from the starboard side: red — All-round red (top), red — All-round red (middle), red — All-round red (bottom), white — Forward masthead light (lower), white — After masthead light (higher), green — Starboard sidelightwhite — After masthead light (higher)All-round red (top)All-round red (middle)white — Forward masthead light (lower)All-round red (bottom)green — Starboard sidelight
Side view, seen from starboard — only the lights visible from that side are shown.
Light profile seen from dead ahead: red — All-round red (top), red — All-round red (middle), red — All-round red (bottom), white — Forward masthead light (lower), white — After masthead light (higher), red — Port sidelight, green — Starboard sidelight
From dead ahead (her green appears on your left).
Light profile seen from astern: red — All-round red (top), red — All-round red (middle), red — All-round red (bottom), white — Sternlight
From astern.

In fog, she sounds

Hampered vessel (fog)— · ·
One prolonged + two short blasts every 2 minutes — not under command, restricted in ability to maneuver, constrained by draft (International), sailing, fishing, or towing/pushing.

Don’t confuse with…

Vessel not under command (NUC): night lights preview
Vessel not under command (NUC)
Rule 27
Vessel aground: night lights preview
Vessel aground
Rule 30
Vessel restricted in ability to manoeuvre (RAM): night lights preview
Vessel restricted in ability to manoeuvre (RAM)
Rule 27

Official source

Rule 28, reproduced from the public-domain COLREGs Rule 28 — USCG Navigation Rules. Diagrams and 3D scenes are original to boatrules.com.

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