Deck Logbook Reference: Wind, Sea, and Weather Condition Codes

Introduction
Deck logbooks require standardized meteorological observations for safety and reporting. The tables below compile the practical codes used for wind, sea state, visibility, sky condition, and wind direction.

Wind Force – The Beaufort Scale

Force	Name	Knots	Sea Condition
0	Calm	<1	Sea like a mirror
1	Light Air	1–3	Ripples, no foam
2	Light Breeze	4–6	Small wavelets
3	Gentle Breeze	7–10	Large wavelets
4	Moderate Breeze	11–16	Small waves, whitecaps
5	Fresh Breeze	17–21	Moderate waves
6	Strong Breeze	22–27	Large waves, foam streaks
7	Near Gale	28–33	Sea heaps up
8	Gale	34–40	Moderately high waves
9	Strong Gale	41–47	High waves, spray
10	Storm	48–55	Very high waves
11	Violent Storm	56–63	Exceptionally high waves
12	Hurricane	64+	Air filled with foam & spray

Sea State – WMO Code

Code	Description	Wave Height (m)
0	Calm (Glassy)	0
1	Rippled	0–0.1
2	Smooth	0.1–0.5
3	Slight	0.5–1.25
4	Moderate	1.25–2.5
5	Rough	2.5–4
6	Very Rough	4–6
7	High	6–9
8	Very High	9–14
9	Phenomenal	≥14

Visibility (Logbook Numeric Codes – 0 to 8)

Code	Meaning	Distance
0	Dense fog – objects at 50 m not visible	~50 m
1	Thick fog	~200 m
2	Fog	~1,000 m
3	Moderate/neutral fog	~2,000 m
4	Mist or light haze	~4,000 m
5	Poor visibility	~7,000 m
6	Normal visibility	~12,000 m
7	Good visibility	~20,000 m
8	Very good visibility – objects beyond 20,000 m visible	>20,000 m

Sky Condition & Meteorological Abbreviations

Code	Meaning
b	Blue sky (0/8 clouded)
bc	Sky partly clouded (3–5/8 clouded)
c	Cloudy (6–8/8 clouded)
o	Overcast sky (completely covered with a uniform layer of thick/heavy cloud)
d	Drizzle
e	Wet air (humid, no rain)
f	Fog
g	Gale
h	Hail
l	Lightning
m	Mist
p	Passing showers
q	Squall / squally weather
r	Rain
rs	Sleet (rain and snow together)
s	Snow
t	Thunder
u	Ugly, threatening sky
v	Pure air (abnormally clear visibility)
w	Dew
x	Hoar frost
y	Dry air
z	Haze

Wind Direction

Abbr.	Direction	Degrees
N	North	0°/360°
NNE	North-Northeast	22.5°
NE	Northeast	45°
ENE	East-Northeast	67.5°
E	East	90°
ESE	East-Southeast	112.5°
SE	Southeast	135°
SSE	South-Southeast	157.5°
S	South	180°
SSW	South-Southwest	202.5°
SW	Southwest	225°
WSW	West-Southwest	247.5°
W	West	270°
WNW	West-Northwest	292.5°
NW	Northwest	315°
NNW	North-Northwest	337.5°

Conclusion

Standardized reporting of wind, sea, visibility, and weather ensures that navigational records are accurate and internationally consistent. These codes form the foundation of deck logbook entries and are essential for safe maritime operations.

Deck Logbook Reference: Wind, Sea, and Weather Conditions