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Not under command, restricted work and grounding: signal additions

Status, way through the water and work change the set; memorising a colour is insufficient.

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Manual contents
In this guide
Separate cores: not under command two reds and two balls; restricted manoeuvrability red-white-red and ball-diamond-ball; constrained draught three reds or cylinder; grounding two additional reds and three balls. Additions and thresholds are in text. Mine clearance/dredging are not depicted as these cores.
Special states · core signals

Original interpretation schematic with declared functions and references. No scale, approved installation or operational track.

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Separate cores: not under command two reds and two balls; restricted manoeuvrability red-white-red and ball-diamond-ball; constrained draught three reds or cylinder; grounding two additional reds and three balls. Additions and thresholds are in text. Mine clearance/dredging are not depicted as these cores.

A yacht experiencing difficulty cannot freely choose a restricted-manoeuvrability signal. Rule 3 distinguishes an exceptional circumstance from restriction through the nature of work.

Rule 27 links signals to those definitions; Rule 28 addresses draught and Rule 30 grounding. The figure compares core signals separately from movement, anchoring and activity additions.

Dots represent colour and order; black shapes represent daytime signals. They are not all elements of an installation.

Not under command and restricted manoeuvrability

Not under command under 27(a): two all-round red lights vertically and two balls vertically. Making way through the water adds sidelights and sternlight.

A masthead is not added simply because the hull normally uses machinery. Restricted manoeuvrability, except mine clearance, under 27(b) uses all-round red-white-red and ball-diamond-ball.

Making way adds masthead or mastheads, sidelights and sternlight; at anchor it adds Rule 30 signals, subject to the special provision in 27(d).

Dredging and underwater work with obstruction add, under 27(d), two reds or two balls on the obstructed side and two greens or two diamonds on the side another vessel may pass. At anchor it uses that paragraph’s signals instead of Rule 30.

This identifies a side but supplies no available draught or universal clearance. Diving where vessel size makes the full set impracticable has its own 27(e) alternative, including a rigid replica of flag A with all-round visibility.

Draught, mine clearance and length

Constrained by draught is defined relative to available navigable depth and width. Rule 28 permits three vertical all-round reds or a cylinder in addition to the machinery lights in 23(a).

It does not replace those lights or describe every large vessel. Mine clearance under 27(f) uses three greens or three balls in its specific arrangement alongside machinery or anchor signals; the text identifies approach within one thousand metres as dangerous.

That is not three vertical greens or permission beyond that limit.

Rule 27(g) exempts vessels below twelve metres from that rule’s signals, except vessels engaged in diving. It does not exempt Rules 5 to 8 or all regulatory lights.

Paragraph (h) distinguishes these signals from distress and assistance signals. Two reds do not automatically mean a Mayday transmission.

Learning must retain the rule, length and operation justifying each presence or absence.

Aground differs from anchored

Rule 30(d) adds two vertical all-round reds to the anchor lights; by day it prescribes three vertical balls. Below twelve metres, 30(f) exempts those additions but does not erase anchor lights required by (d).

Three balls are neither the single anchor ball nor the mine-clearance arrangement. Insufficient depth beneath a grounded hull differs physically from holding by an anchor.

A real view may obscure part of a set; counting visible elements does not prove the complete configuration.

Sources and references

  1. COLREGs Annex IV — Distress signals ↗

    Instituto Hidrográfico / International Maritime Organization · Annex IV; printed p.79, PDF p.85; International cross-check USCG.

    Annex IV, IH printed p.79 (PDF p.85); cross-check International annex in USCG handbook. Installation/approval is not taught.

    Checked on
  2. RIEAM / COLREGs — Rule 28: Vessels constrained by their draught ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 28, normative Portuguese printed p.48 (PDF p.54); International English cross-check in USCG handbook.

    Rule 28; IH normative Portuguese printed p.48, PDF p.54; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  3. RIEAM / COLREGs — Rule 36: Signals to attract attention ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 37, normative Portuguese printed p.59 (PDF p.65); International English cross-check in USCG handbook.

    Rule 37; IH normative Portuguese printed p.59, PDF p.65; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  4. USCG amalgamated rules — International current web cross-check ↗

    United States Coast Guard Navigation Center · International/shared Rules 3,20–30,32–35; International Annexes I–III. International-only wording identified by angle-bracket legend; all Inland insertions excluded. Rule35(j)/(k) compared with IH normative Portuguese printed55/PDF61 and English appendix89–90/PDF95–96.

    Directly read 11 October2026 alongside freshly fetched corrected-August2024 official handbook. Current page confirms under12 paragraph(j) and pilot(k); Portuguese IH agrees; its English appendix differs. Access is not qualified legal approval. No unsupported exact consolidation date assigned.

    Checked on
  5. RIEAM / COLREGs — Rule 23: Power-driven vessels underway ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 23, normative Portuguese printed p.31 (PDF p.37); International English cross-check in USCG handbook.

    Rule 23; IH normative Portuguese printed p.31, PDF p.37; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  6. RIEAM / COLREGs — Rule 4: Application of Section I ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 5, normative Portuguese printed p.7 (PDF p.13); International English cross-check in USCG handbook.

    Rule 5; IH normative Portuguese printed p.7, PDF p.13; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  7. RIEAM / COLREGs — Rule 18: Responsibilities between vessels ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 18, normative Portuguese printed p.23 (PDF p.29); International English cross-check in USCG handbook.

    Rule 18; IH normative Portuguese printed p.23, PDF p.29; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  8. RIEAM / COLREGs — Rule 2: Responsibility ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 3, normative Portuguese printed p.3 (PDF p.9); International English cross-check in USCG handbook.

    Rule 3; IH normative Portuguese printed p.3, PDF p.9; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  9. RIEAM / COLREGs — Rule 6: Safe speed ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 7, normative Portuguese printed p.8 (PDF p.14); International English cross-check in USCG handbook.

    Rule 7; IH normative Portuguese printed p.8, PDF p.14; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  10. COLREGs Annex I — Positioning and technical details of lights and shapes ↗

    Instituto Hidrográfico / International Maritime Organization · Annex I; printed p.65, PDF p.71; International cross-check USCG.

    Annex I, IH printed p.65 (PDF p.71); cross-check International annex in USCG handbook. Installation/approval is not taught. International/Inland distinction checked in the USCG PDF: International §3(a) half-length/100m agrees with IH; the quarter-length/50m value belongs to U.S. Inland and is not imported. No dimensional installation prescription is reproduced.

    Checked on
  11. RIEAM / COLREGs — Rule 27: Vessels not under command or restricted in their ability to manoeuvre ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 27, normative Portuguese printed p.43 (PDF p.49); International English cross-check in USCG handbook.

    Rule 27; IH normative Portuguese printed p.43, PDF p.49; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  12. RIEAM / COLREGs — Rule 29: Pilot vessels ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 30, normative Portuguese printed p.49 (PDF p.55); International English cross-check in USCG handbook.

    Rule 30; IH normative Portuguese printed p.49, PDF p.55; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on
  13. RIEAM / COLREGs — Rule 8: Action to avoid collision ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 8, normative Portuguese printed p.9 (PDF p.15); International English cross-check in USCG handbook.

    Rule 8; IH normative Portuguese printed p.9, PDF p.15; English International column cross-check. Individual provision commencement not established: valid_from remains null.

    Checked on

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