Rule 25 · USCG Navigation Rules
Under sail and power (motorsailing)
Sails up but engine engaged: she is a power-driven vessel — full Rule 23 lights at night and a cone, point down, by day.
Viewpoint
Display
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From the port bow you see:
- white — Masthead light
- red — Port sidelight
→ Under sail and power (motorsailing) — Under sail and power, seen from the port bow.
US Inland difference
Under the Inland Rules a motorsailing vessel of less than 12 m is not required to exhibit the cone.
Choose International or Inland in language and regional settings in the site header.
Memory aid
“Engine on = power boat, no matter the sails. Cone point down says 'motoring' by day.”
What it means
Under sail and power
Top exam trap: the sails change nothing. With the engine propelling her she ranks as power-driven — masthead light at night, conical shape apex downwards forward by day, and she gives way like a power vessel.
Day shapes
Cone, apex down
One conical shape, apex downwards, forward where it can best be seen — sails set but engine driving.
Light details
| Light | Colour | Arc | Position |
|---|---|---|---|
| Masthead light | white | 225° forward | Forward masthead position |
| Port sidelight | red | 112.5° to port | Port side, deck level |
| Starboard sidelight | green | 112.5° to starboard | Starboard side, deck level |
| Sternlight | white | 135° aft | Stern |
2D profile
Labelled side view — works without WebGL and in print. Variant shown: Under sail and power.
In fog, she sounds
Don’t confuse with…
Official source
Rule 25, reproduced from the public-domain COLREGs Rule 25(e) — USCG Navigation Rules. Diagrams and 3D scenes are original to boatrules.com.