The sea state must be recorded during every Shorewatch because it affects the probability of a sighting. For this reason Shorewatch is not carried out when sea state is above 4*.
The Beaufort Sea State Code is a simple scale that can be used to give an approximate but concise description of sea conditions. It is a visual method to assess wind speed in the marine environment. All WDC cetacean researchers use the Beaufort Sea State Code as part of their shorewatch protocol.
Using your binoculars assess the sea state of the whole survey area using the WDC Shorewatch Sea State Key (one in every shorewatch kit). Record the greatest sea state observed within the survey area, discounting coastal surf and waves breaking on the shore. Record your final assessment of sea state as a whole number i.e. 0, 1, 2, 3 or 4 (not: 2-3 or 2.5) in the sea state column on your data sheet before beginning your 10-minute Shorewatch.
*Note: If the sea state is above 4 DO NOT carry out a shorewatch; make regular checks of the sea state. If/when sea state drops conduct a Shorewatch later in the day/week.
Beaufort Sea State Codes
Sea State 0
Conditions: Sea like a mirror.
Wind Speed: Under 1 knot (smoke rises vertically)
Wave Height: 0 feet
Sea State 1
Wind Speed: 1 - 3 knots (wind motion visible in smoke)
Wave Height: 0.33 feet/10cm
Sea State 2
Conditions: Small wavelets all over. No whitecaps.
Wind Speed: 4 - 6 knots (wind felt on exposed skin and leaves rustle)
Wave Height: 0.66 feet/20cm
Tip: The distinction between a sea state 2 and 3 is easy to determine; as soon as you can see any white caps within your survey area it is a sea state 3. No white caps on the wavelets and it is a sea state 2!
Sea State 3
Conditions: Large wavelets. Few white caps here and there.
Wind Speed: 7 - 10 knots (leaves and smaller twigs in constant motion)
Wave Height: 2 feet/60cm
Sea State 4
Conditions: Small waves. Fairly frequent white caps.
Wind Speed: 11 - 16 knots (dust and loose paper raised. Small branches begin to move)
Wave Height: 3.3 feet/1m
Sea State 5
Conditions: Moderate waves. Many white caps. Spray possible.
Wind Speed: 17 - 21 knots (branches of a moderate size move. Small trees begin to sway)
Wave Height: 6.6 feet/2m