Sailing Vessel Lights and Day Shapes (Rule 25)

Introduction

Rule 25 (Sailing Vessels Underway and Vessels Under Oars), detailed in 33 CFR 83.25, governs vessels propelled by sail alone. A sailing vessel enjoys privileged status in the vessel hierarchy-under Rule 18, a sailing vessel is a "stand-on" vessel when encountering a power-driven vessel (the power vessel must give way). The navigation lights for sailing vessels are specifically designed to clearly communicate this privileged status while also showing the vessel's aspect and direction.

Critical Definition: The term "sailing vessel" applies only when the vessel is under sail alone, with no engine engaged. As soon as a sailing vessel engages its engine, even if the sails remain up and drawing, it legally becomes a "power-driven vessel" and must display the lights prescribed for power-driven vessels in Rule 23.

This distinction is one of the most commonly misunderstood and frequently violated aspects of the Navigation Rules, with serious legal and safety consequences.

Under Sail Alone: The Three Lighting Options

Rule 25 provides three distinct lighting options for a vessel operating under sail alone. Sailing vessels may choose which option to use based on vessel size, electrical system capacity, and visibility preferences.

###Option 1: The Baseline Configuration (Rule 25a)

This is the most basic configuration, required for all sailing vessels unless they elect to use one of the alternative options permitted below. It consists of:

1. Sidelights: Red (port) and green (starboard) 112.5° lights
2. A Sternlight: A 135° white light

Installation: On larger sailboats (over 20 meters), these sidelights are typically mounted on the hull near the bow, on the "pulpit" (bow rail), or on the lower portion of the mast. The sternlight is mounted on the stern rail or on the aft portion of the cabin.

Advantages:

• Simple, reliable configuration
• Widely spaced lights clearly show the vessel's aspect
• No height restrictions-works for all vessel sizes
• Redundancy if using separate port and starboard lights

Disadvantages:

• Low-mounted sidelights can be obscured by waves in rough seas
• Can be "lost" in shoreline clutter or harbor lights
• Requires three separate lights (more power consumption, more potential points of failure)
• May be difficult to see at long ranges due to lower mounting height

Option 2: The Combined Lantern / Tri-Color Light (Rule 25b)

For a sailing vessel of less than 20 meters (65.6 ft) in length, the rules provide a popular and efficient alternative. Such a vessel may combine the sidelights and sternlight into a single lantern, commonly called a "tri-color light," carried "at or near the top of the mast where it can best be seen."

This single light unit displays:

• Red light in the 112.5° port sector
• Green light in the 112.5° starboard sector
• White light in the 135° stern sector

Advantages:

• High visibility: Mounting at the masthead (often 30-50 feet above water) lifts the light clear of waves, making it visible at maximum range
• Power efficiency: One bulb with three colored lens sectors uses significantly less power than three separate lights-critical for cruising sailboats with limited battery capacity
• Simplicity: Single installation point, single wire run, one bulb to replace
• Distinctive: High white light is easily distinguished from power vessel configurations

Disadvantages:

• No redundancy: If the single bulb fails, the vessel becomes unlighted with no backup
• Small size: From a distance, the single small light may be harder to identify than widely-spaced hull lights
• Mast motion: In rough seas, mast movement can make the light appear to "dance," potentially confusing observers
• Rigging obstruction: Stays, spreaders, and sail material can intermittently block the light

Option 3: The Optional All-Round Lights (Rule 25c)

A sailing vessel of any size may, in addition to the baseline lights (Option 1), exhibit two all-round lights at or near the top of the mast in a vertical line:

1. Upper Light: All-round Red (360°)
2. Lower Light: All-round Green (360°)

Important: These red-over-green lights are in addition to, not in lieu of, the vessel's sidelights and sternlight. The vessel still displays its low-mounted or combined sidelights and sternlight to indicate direction, but adds the high-visibility red-over-green stack to clearly announce its status as a sailing vessel from all directions.

The Mnemonic: "Red over Green, Sailing Machine" is the universal memory aid for identifying sailing vessels at night.

When to Use Option 3:

• Heavy commercial traffic areas where maximum visibility is critical
• Approaches to busy harbors or shipping channels
• Ocean passages where early identification is important
• Any situation where the operator wants to maximize visibility and clearly declare sailing vessel status

Crucial Prohibition (Rule 25c): A vessel using the combined tri-color light (Option 2) cannot simultaneously display the optional red-over-green lights (Option 3). This prohibition is absolute and is essential to prevent signal confusion.

Why This Prohibition Exists: A tri-color light at the masthead combined with a red-over-green stack would create a confusing and ambiguous pattern of red, green, and white lights at the masthead. This could be mistaken for a fishing vessel, a vessel restricted in ability to maneuver, or a vessel not under command-all of which carry very different right-of-way implications.

Legal Choice: A sailing vessel must choose:

• Option 1 alone (baseline sidelights + sternlight), OR
• Option 2 alone (tri-color at masthead), OR
• Option 1 + Option 3 together (sidelights + sternlight + red-over-green)

Any other combination violates Rule 25 and constitutes improper lighting.

Sail AND Power: The "Motorsailer" Rule (Rule 25e)

This is the most critical, and most frequently violated, aspect of Rule 25. The consequences of non-compliance are severe, both legally and in terms of collision risk.

The Rule: A sailing vessel "proceeding under sail when also being propelled by machinery" is legally defined as a power-driven vessel.

This definition is found in Rule 3(b) (General Definitions) and is reinforced in Rule 25(e). The moment the engine engages, regardless of whether sails are up, down, furled, or drawing, the vessel's legal status changes completely.

Legal Status Change and Consequences

As a power-driven vessel, the motorsailer's responsibilities under the "pecking order" (Rule 18) are completely reversed:

As a Sailing Vessel (engine off, under sail alone):

• Stand-on to power-driven vessels
• Give-way to vessels not under command, restricted in ability to maneuver, and engaged in fishing

As a Power-Driven Vessel (engine on, even with sails up):

• Give-way to sailing vessels
• Give-way to vessels not under command, restricted in ability to maneuver, and engaged in fishing
• Equal status with other power-driven vessels (crossing/head-on/overtaking rules apply)

This reversal of privilege is absolute. A motorsailer has no right to stand on against a pure sailing vessel, even if the motorsailer's sails are doing 90% of the work and the engine is barely assisting.

Required Signals for Motorsailers

To communicate this change in legal status, the motorsailer must display different signals by day and by night:

At Night (Sunset to Sunrise):

The vessel must:

1. Turn OFF all sailing-specific lights:
   • Tri-color light at masthead (if using Option 2)
   • Red-over-green all-round lights (if using Option 3)
2. Turn ON the lights for a power-driven vessel of its length:
   • Masthead light forward (minimum requirement)
   • Sidelights
   • Sternlight

The forward-facing white masthead light is the critical signal that distinguishes a motorsailer from a pure sailing vessel. Sailing vessels never display a forward-facing white masthead light in the sailing vessel light pattern.

By Day (Sunrise to Sunset):

The vessel must exhibit, forward and where it can best be seen:

A conical shape, apex downward (a black cone pointing down)

This day shape is sometimes called the "cone of confession" or "cone of shame" in sailing circles. It is a visual declaration that the vessel, despite having its sails hoisted and potentially drawing well, is operating under power and surrenders its stand-on privilege as a pure sailing vessel.

Size Exemption: Vessels less than 12 meters in length are not required to display the cone day shape, though it is strongly recommended for safety.

Material and Specifications: The cone must meet the specifications in 33 CFR 84.06:

• Black in color
• Diameter at base: at least 0.6 meters (23.6 inches)
• Height equal to its diameter

Why This Matters: Real-World Scenarios

Scenario 1: Harbor Approach

A 40-foot motorsailer is motorsailing into a busy harbor under main and jib with the engine running at 1500 RPM for better control. A 35-foot power cruiser is approaching on a crossing course with the motorsailer on its starboard side.

If improperly lit (showing sailing lights without masthead light):

• The power cruiser's operator sees sailing lights and correctly identifies a "sailing vessel"
• Under Rule 18, the power vessel is give-way and must maneuver to avoid
• The power vessel alters course to starboard to pass astern
• COLLISION: The motorsailer, seeing a vessel giving way, maintains course-but then suddenly accelerates with engine power, arriving at the crossing point faster than the power vessel expected

If properly lit (showing power-driven vessel lights):

• The power cruiser identifies another power-driven vessel
• Crossing Rules (Rule 15) apply: motorsailer (on starboard) is stand-on
• Power cruiser gives way as required
• Safe passage

Scenario 2: The Legal Consequences

In 2018, a motorsailer was involved in a collision in Puget Sound. The sailing vessel had sails up and engine running but was displaying only sailing vessel lights (tri-color at masthead, no masthead light forward). A commercial fishing vessel, seeing the sailing lights, gave way under Rule 18. The motorsailer, misunderstanding its own legal status, maintained course and speed. Due to unexpected current, the vessels collided.

Coast Guard investigation determined:

• The motorsailer was legally a power-driven vessel (engine was running)
• The motorsailer was improperly lit (failed to display masthead light)
• The motorsailer failed to display the day shape (cone)
• Under the Pennsylvania Rule, the motorsailer was presumed at fault

Penalties assessed:

• $18,610 for improper lighting (33 U.S.C. 2072)
• $18,610 for failure to display day shape
• Total civil penalties: $37,220
• Civil lawsuit from fishing vessel for damages: $127,000
• Insurance denied coverage due to willful violation of federal regulations

Practical Compliance

Best Practices for Motorsailers:

1. Pre-departure checklist: Verify all light configurations are functional:

   • Sailing lights (tri-color or sidelights + sternlight)
   • Power lights (masthead forward)
   • Day shape (cone) is aboard and accessible

2. Engine start procedure:

   • The moment the engine engages, immediately switch from sailing lights to power lights
   • Hoist the cone day shape
   • Brief crew on change of status and right-of-way implications

3. Engine stop procedure:

   • The moment the engine disengages and propeller stops turning, switch from power lights back to sailing lights
   • Lower the cone day shape
   • Brief crew on change of status

4. When in doubt, display power lights: If the engine might be needed (heavy traffic, narrow channel, adverse weather), it's safer to display power vessel lights and day shape even under sail

Small Sailboats and Vessels Under Oars (Rule 25d)

Rule 25(d) addresses very small sailing vessels and vessels being propelled by oars (rowing) or paddles.

For a sailing vessel less than 7 meters (23 feet) in length:

The vessel shall, if practicable, exhibit the lights prescribed in Rule 25(a), (b), or (c) above. If this is not practicable, the vessel must have ready at hand:

An electric torch or lighted lantern showing a white light

This light must be exhibited in sufficient time to prevent collision.

Practical Application: A small sailing dinghy (e.g., a Sunfish, Laser, or small catboat) sailing at night may not have electrical power for navigation lights. The operator must carry a flashlight and, when another vessel approaches, shine the white light to reveal the dinghy's presence and location.

For vessels under oars (rowboats, kayaks, canoes, paddleboards):

The same rule applies. A kayak being paddled at night must have a white light (flashlight, headlamp, or battery lantern) ready at hand and must display it when other vessels approach.

Federal vs. State Requirements:

Note that many states have more restrictive requirements than federal rules for small craft. For example:

• California requires kayaks to display a white light visible from 360° at all times between sunset and sunrise
• Florida requires all vessels, regardless of size, to display proper navigation lights
• Many states prohibit operation of vessels under 16 feet after dark entirely

Always check state regulations in addition to federal requirements.

Summary

Sailing vessels under sail alone have three lighting options: baseline sidelights and sternlight (Rule 25a), combined tri-color at masthead for vessels <20m (Rule 25b), or baseline lights plus optional red-over-green all-round lights (Rule 25c). The tri-color and red-over-green options cannot be used together.

The critical motorsailer rule requires that any sailing vessel with engine engaged must immediately change to power-driven vessel lights (displaying a forward white masthead light) at night and must display a black cone apex-down by day. This signals the change in legal status from stand-on to give-way relative to pure sailing vessels. Failure to comply carries severe penalties and presumed fault in collisions.

Small sailing vessels under 7 meters and vessels under oars must carry a white light ready to display when needed. State regulations may impose stricter requirements than federal rules.

Key Takeaways

• Sailing vessel status applies ONLY when under sail alone-engine off, propeller not turning
• Three lighting options: sidelights+sternlight, tri-color at mast (‹20m only), or sidelights+sternlight+red-over-green
• "Red over Green, Sailing Machine" identifies optional all-round lights
• Tri-color and red-over-green cannot be displayed simultaneously
• Motorsailers (engine on, even with sails up) must display forward white masthead light at night
• Motorsailers must display black cone apex-down by day (except vessels <12m)
• Motorsailers lose stand-on privilege-they become give-way to pure sailing vessels
• Improper motorsailer lighting is a common violation with severe penalties
• Small vessels (<7m) and vessels under oars must carry white light ready at hand