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Rule 27 · USCG Navigation Rules

Tug severely restricted in ability to deviate (tug + RAM)

A towing operation that cannot deviate from her course adds red-white-red RAM lights and ball-diamond-ball to the normal towing lights.

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 — Masthead light (upper of two = tow ≤ 200 m)
  • white — Masthead light (lower of two)
  • All-round red (top of RAM group)
  • All-round white (middle of RAM group)
  • All-round red (bottom of RAM group)
  • red — Port sidelight

→ Tug severely restricted in ability to deviate (tug + RAM) — Restricted tow (drawn with tow ≤ 200 m), seen from the port bow.

Memory aid

“A tug that can't turn: towing whites up top plus red-white-red.”

What it means

Restricted tow (drawn with tow ≤ 200 m)

Rule 24 towing lights PLUS Rule 27(b)(i)–(ii). Drawn on one mast here — the red-white-red group may be carried where it can best be seen, e.g. on an after mast. With a tow over 200 m she shows three masthead lights and adds the diamond.

Day shapes

  • Day shape: Ball – diamond – ball

    Ball – diamond – ball

    The RAM day shape, in addition to any tow-length diamond.

Light details

LightColourArcPosition
Masthead light (upper of two = tow ≤ 200 m)white225° forwardMast, vertical line (top)
Masthead light (lower of two)white225° forwardMast, vertical line (2nd from top)
All-round red (top of RAM group)red360° all-roundMast, vertical line (3rd from top)
All-round white (middle of RAM group)white360° all-roundMast, vertical line (4th from top)
All-round red (bottom of RAM group)red360° all-roundMast, vertical line (5th from top)
Port sidelightred112.5° to portPort side, deck level
Starboard sidelightgreen112.5° to starboardStarboard side, deck level
Sternlightwhite135° aftStern
Yellow towing light, above the sternlightyellow135° aftAft, raised above the stern

2D profile

Labelled side view — works without WebGL and in print. Variant shown: Restricted tow (drawn with tow ≤ 200 m).

Light profile seen from the starboard side: white — Masthead light (upper of two = tow ≤ 200 m), white — Masthead light (lower of two), red — All-round red (top of RAM group), white — All-round white (middle of RAM group), red — All-round red (bottom of RAM group), green — Starboard sidelightwhite — Masthead light (upper of two = tow ≤ 200 m)white — Masthead light (lower of two)All-round red (top of RAM group)All-round white (middle of RAM group)All-round red (bottom of RAM group)green — Starboard sidelight
Side view, seen from starboard — only the lights visible from that side are shown.
Light profile seen from dead ahead: white — Masthead light (upper of two = tow ≤ 200 m), white — Masthead light (lower of two), red — All-round red (top of RAM group), white — All-round white (middle of RAM group), red — All-round red (bottom of RAM group), 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 of RAM group), white — All-round white (middle of RAM group), red — All-round red (bottom of RAM group), white — Sternlight, yellow — Yellow towing light, above the 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 towing astern (tow 200 m or less): night lights preview
Vessel towing astern (tow 200 m or less)
Rule 24
Vessel restricted in ability to manoeuvre (RAM): night lights preview
Vessel restricted in ability to manoeuvre (RAM)
Rule 27

Official source

Rule 27, reproduced from the public-domain COLREGs Rule 27(c) — USCG Navigation Rules. Diagrams and 3D scenes are original to boatrules.com.

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