[vc_row][vc_column width=”2/3″][vc_single_image image=”122975″ img_size=”full” alignment=”center” style=”vc_box_border”][vc_column_text]LEARNING TO UNDERSTAND THE FORECAST
Knowing the weather forecast before putting to sea is absolutely essential to avoid unexpected rough conditions which could quickly lead to disaster. However, there is obviously little point in hearing that forecast if you don’t understand what it means.
As part of a Boats & Berths series for nautical newcomers, we look at the globally accepted means of measuring the wind speed, and translating that into gauging the likely condition of the sea — plus a profile of the man who invented the Beaufort scale.
Measuring weather around the world – thanks to Admiral Sir Francis Beaufort
While the name suggests French origins, and some historic records refer to Huguenot ancestry, the man who became globally famous for devising a method of measuring the wind force was, in fact, an Irishman.
Francis Beaufort was born in 1774, in County Meath, Ireland, and began his nautical career as a cabin boy in the British Navy at the age of 13.
According to the website, Weather Doctor, Francis Beaufort soon recognised the value of being weather-wise and began keeping a meteorological journal in the form of brief comments on the general weather scene.
In 1805, Beaufort was given his first command, HMS Woolwich, and during these early years of command, he developed the first versions of his Wind Force Scale and Weather Notation coding, which he was to use in his journals for the remainder of his life.
It was an injury which, ironically, gave him the time to perfect his accomplishment.
Beaufort’s assignment during the years 1811 and 1812 led him to the Eastern Mediterranean for a combined hydrographic study and patrol mission against the pirates operating out of the Levant.
In June, 1812, Beaufort sent a survey party ashore to make astronomical observations. When the party encountered armed hostilities from the local pashas, Beaufort himself led the rescue. As they were rowing back to HMS Fredrikssteen, Beaufort was struck in the groin by sniper fire. The ball fractured his hip, and he subsequently spent several months convalescing aboard ship.
By the end of the year, however, it was obvious that both ship and commander were in great need of repair, and they were ordered home by the Admiralty.
Francis Beaufort would never again return to active sea duty although he would remain in the British Navy until he was 81.
Promoted to Rear Admiral in 1846, Beaufort was bestowed the title Knight Commander of the Bath two years later. In 1855, after 68 years of service, Sir Francis retired from the Admiralty. He died in 1857.
The Beaufort scale with the force number, wind speed, wave height and likely conditions at sea and on land.
|
Beaufort Number |
Description |
Wind |
Wave Height |
Sea Conditions |
Land Conditions |
|
0 |
Calm | > 1 km/h > 1 mph > 1 knot |
0 metres 0 feet |
Sea like a mirror | Calm. Smoke rises vertically. |
|
1 |
Light Air | 1-5 km/h 1-3 mph 1-3 knots |
0-0.2 m 0-1 ft |
Ripples with the appearance of scales are formed, but without foam crests | Smoke drift indicates wind direction. Leaves and wind vanes are stationary. |
|
2 |
Light Breeze | 6-11 km/h 4-7 mph 4-6 knots |
0.2-0.5 m 1-2 ft |
Small wavelets, still short but more pronounced; crests have a glassy appearance and do not break | Wind felt on exposed skin. Leaves rustle. Wind vanes begin to move. |
|
3 |
Gentle Breeze | 12-19 km/h 8-12 mph 7-10 knots |
0.5-1 m 2-3.5 ft |
Large wavelets. Crests begin to break; scattered whitecaps | Leaves and small twigs constantly moving, light flags extended. |
|
4 |
Moderate Breeze | 20-28 km/h 13-18 mph 11-16 knots |
1-2 m 3.5-6 ft |
Small waves with breaking crests. Fairly frequent whitecaps. | Dust and loose paper raised. Small branches begin to move. |
|
5 |
Fresh Breeze | 29-38 km/h 19-24 mph 17-21 knots |
2-3 m 6-9 ft |
Moderate waves of some length. Many whitecaps. Small amounts of spray. | Branches of a moderate size move. Small trees in leaf begin to sway. |
|
6 |
Strong Breeze | 39-49 km/h 25-32 mph 22-27 knots |
3-4 m 9-13 ft |
Long waves begin to form. White foam crests are very frequent. Some airborne spray is present. | Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic bins tip over. |
|
7 |
High wind, moderate gale, near gale | 50-61 km/h 32-38 mph 28-33 knots |
4-4.5 m 13-19 ft |
Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray. | Whole trees in motion. Effort needed to walk against the wind. |
|
8 |
Gale, fresh gale | 62-74 km/h 39-46 mph 34=40 knots |
5.5-7.5 m 18-25 ft |
Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray. | Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded. |
|
9 |
Strong/severe gale | 75-88 km/h 47-54 mph 41-47 knots |
7-10 m 23-32 ft |
High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility. | Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. |
|
10 |
Storm, whole gale | 89-102 km/h 55-63 mph 48-55 knots |
9-12.5 m 29-41 ft |
Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility. | Trees are broken off or uprooted, structural damage likely. |
|
11 |
Violent storm | 103-117 km/h 64-72 mph 56-63 knots |
11.5-16 m 37-52 ft |
Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility. | Widespread vegetation and structural damage likely. |
|
12 |
Hurricane force | ≥ 118 km/h ≥ 73 mph ≥ 64 knots |
≥ 14 m ≥ 46 ft |
Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility. | Severe widespread damage to vegetation and structures. Debris and unsecured objects are hurled about. |
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