- swell (slight, moderate, heavy) and the true direction from which it comes. Period or length of swell (short, average, long) would also be of value;
- true course and speed of ship.
3 Subsequent observations
When a master has reported a tropical cyclone or other dangerous storm, it is desirable but not obligatory, that further observations be made and transmitted hourly, if practicable, but in any case at intervals of not more than 3 hours, so long as the ship remains under the influence of the storm.
4 Winds of force 10 or above on the Beaufort scale for which no storm warning has been received. This is intended to deal with storms other than the tropical cyclones referred to in paragraph 2; when such a storm is encountered, the message should contain similar information to that listed under the paragraph but excluding the details concerning sea and swell.
5 Sub-freezing air temperatures associated with gale force winds causing severe ice accretion on superstructures
.1 Time and date (Universal Co-ordinated Time).
.2 Air temperature.
.3 Sea temperature (if practicable).
.4 Wind force and direction.
