Rule 31 · USCG Navigation Rules
Seaplane on the water
Where full compliance is impracticable, a seaplane exhibits lights and shapes as closely similar in characteristics and position as possible.
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
- red — Port sidelight
→ Seaplane on the water — Taxiing on the water, seen from the port bow.
Memory aid
“A seaplane lights up like a power boat — as closely as her airframe allows.”
What it means
Taxiing on the water
A seaplane counts as a vessel under the rules. Airframe geometry rarely fits the exact light positions, so Rule 31 asks for the closest practicable approximation of the power-driven pattern.
Day shapes
No special day shape — by day this vessel is recognised by sight, not by shapes.
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: Taxiing on the water.
In fog, she sounds
Don’t confuse with…
Official source
Rule 31, reproduced from the public-domain COLREGs Rule 31 — USCG Navigation Rules. Diagrams and 3D scenes are original to boatrules.com.