Diving Lore

Diving Survival

Storms At Sea

For a sailor, a storm is rarely a welcome sight. It can damage vessels, crack hulls and claim lives. At best a storm can be far to the stern of boat it's brisk wind speeding the ship along. At worst it can engulf a ship and its crew giving them the fight of their lives.

 

Ocean Hazards

Ocean WeatherWhile the storm is inherently hazardous it can bring about additional dangers and challenges:

The Wave Factor

Even for the strongest vessel the constant pounding of the sea will, eventually weaken and smash wooden deck and planking. Washing aboard and potentially striking crew and equipment. Depending on the wind direction a vessel could well struggle to make headway.

The Rogue Wave

Mother natures fury set into a single solid wave. Seamans tales were abound with vivid and harrowing descriptions of them. Described as every sailors nightmare it is indeed a monster to behold. Rogue waves are not unknown in calm seas but in stormsy weather at sea their likelihood is magnified. Until recently mainstream science scoffed and dismissed claims of rogue waves and their height. But one stormy night the Brent Charlie Platform in the North Sea was struck by an almighty wave, this was caught on camera at a height of 25+ metres. Proving the sailors legend true.
The hallmarks of a rogue wave: A deep trough will usually form and a wall of water will rise up (some say drawing 'energy' from the trough) as if out of nowhere (in relation to the waves around it). It may resemble from a distance an unterrupted line of breakers.
Possibly a darkening of the sky (as the ship is in its shadow). For a captain faced with one of these behemoths there is only one option. Steer into it and hope to avoid a devastating blow to the port or starboard sides is a wise move. Speed ought to be at maxiumum for clearing the wave safetly.

An steel-hulled ocean-going vessel can typically withstand wave heights of up to 15 metres without outright damage. But rogue wave heights exceed 15 metres. Some claim up to 30 metres is typical. Once the ordinary height of waves is lapsed metal cannot shrug off the onslaught.
Steel will buckle, welds will fracture and a vessel can be in grave danger of sinking. In the case of a smaller vessel complete destruction and loss is likely. While Rogue Waves are rarely encountered they are by no means a rare phenomenon. Thankfully they usually only occur in deep oceanic waters.

Storm Winds

Wind at sea is normally nothing unusual. But in a storm the wind which can work in a boat captains favour can be deadly. Besides the damage it can do to canvas sails and rigging. It can injure crew and even send them overboard. For the vessel itself even it is not impervious. The buffetting and onslaught can result in being blown off course. In open seas a problem. In enclosed waters with deadly shoals , rocks and shallows foundering can be inevitable.

Lightning At Sea

Often the least thought of hazard in storms at sea but a dangerous and terrifying occurance. While the water around a vessel might conduct electricity somewhat a soaking-wet metal ship is a perfect lightning conductor. Keeping the crew in and below decks is all that can be done in case it strikes down on or nearby.

The ways of the weather scale

One method of gauging the weather conditions at sea and land is to use the Beauford Scale. An old method but reliably gathered from the age of sail in the 19th Century. On a scale of 0 to 12 (up to 17 in Asia for cyclones) it tells a story:

Beauford Scale

Force   Wind Speed (knots) On Water On Land
0 Below 1 Dead Calm Sea surface smooth and glass-like Smoke rises vertically
1 1 - 3 Light Air Scaly ripples, no foam crests Smoke drift indicates wind direction, still wind vanes
2 4 - 6 Slight Breeze Small wavelets, crests glassy, no breaking Wind felt on face, leaves rustle, vanes begin to move
3 7 - 10 Gentle Breeze Large wavelets, crests begin to break, scattered whitecaps Leaves and small twigs constantly moving, light flags extended
4 11 - 16 Moderate Breeze Small waves 1-4 ft. becoming longer, numerous whitecaps Dust, leaves, and loose paper lifted, small tree branches move
5 17 - 21 Fresh Breeze Moderate waves 4-8 ft taking longer form, many whitecaps, some spray Small trees in leaf begin to sway
6 22 - 27 Strong Breeze Larger waves 8-13 ft, whitecaps common, more spray Larger tree branches moving, whistling in wires
7 28 - 33 Near Gale Sea heaps up, waves 13-20 ft, white foam streaks off breakers Whole trees moving, resistance felt walking against wind
8 34 - 40 Gale Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks Whole trees in motion, resistance felt walking against wind
9 41 - 47 Strong Gale High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility Slight structural damage occurs, slate blows off roofs
10 48 - 55 Storm Very high waves (20-30 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility Seldom experienced on land, trees broken or uprooted, "considerable structural damage"
11 56 - 63 Violent Storm Exceptionally high (30-45 ft) waves, foam patches cover sea, visibility more reduced  
12 64+ Hurricane Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced  

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