COLREGS Rule 12 — Sailing Vessels

Rule Text

What it means on the water

• →Wind on DIFFERENT sides: the vessel with the wind on her PORT side keeps out of the way (the port-tack vessel gives way to the starboard-tack vessel).
• →Wind on the SAME side: the WINDWARD vessel keeps out of the way of the LEEWARD vessel.
• →Uncertainty rule: a port-tack vessel that sees a vessel to windward but cannot tell which tack it is on must keep clear — doubt defaults to keeping out of the way.
• →Windward side = the side OPPOSITE the side on which the mainsail (or largest fore-and-aft sail on a square-rigger) is carried.
• →A vessel's tack is named for the side the wind comes from: wind on the starboard side = starboard tack; wind on the port side = port tack.
• →Rule 12 applies only between two sailing vessels in sight of one another (per Rule 11); it does not override Rule 13 (overtaking), which keeps the overtaking vessel give-way regardless of tack.

Common exam mistakes

• ✗Reversing the tack rule — it is the PORT-tack vessel (wind on the port side) that gives way to the starboard-tack vessel, not the other way around.
• ✗On the same tack, thinking the leeward vessel gives way — it is the WINDWARD vessel that keeps clear of the leeward vessel.
• ✗Misidentifying the windward side — it is the side OPPOSITE the mainsail, not the side the boom is on.
• ✗Forgetting the uncertainty rule — if a port-tack vessel cannot tell the other's tack, she must keep clear; she does not get to stand on.

USCG exam questions — Rule 12

These questions are drawn from the same pool used in real USCG licensing exams. Correct answers and explanations are shown.

1. 1. Under Rule 9, a vessel less than 20 meters in length or a sailing vessel in a narrow channel:

   • A.Has priority over power-driven vessels proceeding along the channel
   • B.Shall not impede the passage of a vessel which can safely navigate only within the channel✓
   • C.May anchor in the channel if no traffic is visible
   • D.Shall keep to the port side of the channel to leave room for larger vessels

   Why: Rule 9(b) places a duty on small vessels and sailing vessels not to impede vessels that can only safely use the channel. This is a proactive obligation — the small or sailing vessel must act to stay clear, rather than simply being low in the hierarchy when an encounter develops.

2. 2. A sailing vessel sees another sailing vessel to windward but cannot determine whether that vessel has the wind on the port or starboard side. Under Rule 12, the vessel to leeward shall:

   • A.Sound five short blasts and maintain course and speed
   • B.Keep out of the way of the vessel to windward✓
   • C.Assume the other vessel is on starboard tack and give way accordingly
   • D.Reduce speed until the windward vessel's tack can be determined

   Why: The keyed answer is correct: under Rule 12(a)(iii), if a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether that vessel has the wind on the port or starboard side, she shall keep out of the way of the other. This is a safety default for the leeward (port-tack) vessel, requiring her to give way to the windward vessel. (Note: Rule 12(b) is the separate definition of the "windward side" — the side opposite that on which the mainsail is carried — and does not govern this ambiguous-tack situation.)

3. 3. Under Rule 14(b), a head-on situation shall be deemed to exist when a vessel sees another vessel ahead and:

   • A.The other vessel's masthead lights are in line and her range lights can be seen
   • B.At night, she can see the masthead lights of the other vessel in a line or nearly in a line, or both sidelights✓
   • C.The bearing to the other vessel does not change over a 3-minute period
   • D.Both vessels are on courses within 10 degrees of each other

   Why: Rule 14(b) specifies the visual indicators of a head-on situation at night: masthead lights in line (or nearly in line) and/or both sidelights visible. This is the practical way mariners identify the head-on meeting without requiring precise course comparison.

4. 4. Under Rule 16, the give-way vessel shall:

   • A.Sound the appropriate signal and then take action
   • B.Take early and substantial action to keep well clear✓
   • C.Reduce speed to half ahead and maintain course until the stand-on vessel reacts
   • D.Alter course to starboard in all situations

   Why: Rule 16 requires the give-way vessel to take early and substantial action to keep well clear. 'Early' prevents last-minute maneuvers; 'substantial' ensures the action is perceptible to the stand-on vessel; 'well clear' sets a high standard that goes beyond merely avoiding collision.

5. 5. Rule 18(d) states that a vessel constrained by her draft shall, in a crossing situation with a sailing vessel:

   • A.Give way to the sailing vessel because sail has precedence over power
   • B.Navigate with particular caution, but the sailing vessel must not impede her✓
   • C.Automatically be considered the stand-on vessel regardless of which side the sailing vessel is on
   • D.Sound two prolonged blasts to signal her constrained status

   Why: Rule 18(d) does not grant a vessel constrained by draft an absolute right of way over sailing vessels. Instead it requires all vessels to navigate with particular caution when a CBD vessel is present. Sailing vessels should take care not to impede her, but the CBD vessel must still navigate with care. This is more nuanced than a simple give-way hierarchy.

6. 6. A sailing vessel proceeding under sail AND using her engine shall display by day:

   • A.A black ball shape forward
   • B.A black cone with apex downward forward✓
   • C.A black diamond shape
   • D.No special day shape is required

   Why: Rule 25(e) requires a sailing vessel proceeding under sail when also being propelled by machinery to show a conical shape, apex downwards, at the forward part of the vessel. This alerts other mariners that despite the sails, she is operating as a power-driven vessel for rules purposes.

7. 7. COLREGS Rule 2 covers the principle of:

   • A.Responsibility — requiring compliance with the rules while allowing departure from them to avoid immediate danger✓
   • B.Definitions — establishing the meaning of key terms used throughout the rules
   • C.Lookout — requiring every vessel to maintain a proper watch at all times
   • D.Safe speed — requiring all vessels to proceed at a speed appropriate to the prevailing conditions

   Why: Rule 2 addresses responsibility, affirming that nothing in the rules shall exonerate a vessel from neglect of seamanship, and allowing departure from the rules when necessary to avoid immediate danger.

8. 8. Rule 2(a) holds who responsible for neglect to comply with the rules?

   • A.The owner, master, and crew of any vessel✓
   • B.Only the master of the vessel
   • C.Only the officer of the watch at the time of the incident
   • D.The vessel's flag state and its authorized classification society

   Why: Rule 2(a) states that nothing in the rules shall exonerate any vessel, or the owner, master, or crew thereof, from the consequences of neglect — holding all parties responsible, not just the officer on watch.

Frequently asked questions

Which sailing vessel gives way when two sailing vessels approach each other?

It depends on the wind. When the two vessels have the wind on different sides, the vessel with the wind on her port side (the port-tack vessel) keeps out of the way of the starboard-tack vessel. When both have the wind on the same side, the windward vessel keeps out of the way of the leeward vessel. If a port-tack vessel cannot determine which tack a windward vessel is on, she keeps clear.

How do you determine the windward side of a sailing vessel under Rule 12?

Rule 12 defines the windward side as the side opposite to the side on which the mainsail is carried — or, on a square-rigged vessel, the side opposite the side on which the largest fore-and-aft sail is carried. In practical terms, the windward side is the side the wind is blowing from, and the sail is pushed out to the leeward side.

Does Rule 12 apply if one sailing vessel is overtaking another?

No. Rule 13 (overtaking) takes precedence over Rule 12. Any vessel overtaking another must keep out of the way of the vessel being overtaken, regardless of tack or windward/leeward position. The tack-based hierarchy of Rule 12 applies only to sailing vessels meeting or crossing, not overtaking.

All COLREGS rules