Avoiding the dangers of rolling white water at sea
There are two types of breaking waves most commonly associated with heavy weather at sea: spilling and plunging. Of the two, plunging breakers are by far the more dangerous.Either kind of breaking wave can capsize a small boat, however. Any wave with a height equal to 55 percent of a typical boat’s overall length has the potential to capsize her.If you’re caught out in bad weather at sea, the standard advice is to avoid breaking waves or, if you can’t, to meet them end-on, because it’s much more difficult to capsize a boat end over end than it is to roll her over sideways. It’s not always possible to act on such advice, however, and often the boat must be left to look after herself.Breakers are formed when the wind pumps too much energy into a wave system in too short a time; the crest of the wave must get rid of excess energy by breaking, or spilling over. The same thing happens when a strong current flows against the wind and the seas are heaped up unnaturally steeply, or when the bottom of a wave hits shallows and is slowed down. It’s physically impossible for a wave to maintain a stable form when its face exceeds a steepness ratio of 1:7.The crest of a wave reaching steeply shelving land can spill over suddenly and with great energy, forming the thunderous plunging breakers we call surf. Or, in deep water, the crest can topple over and pour more gently down the face of the wave, forming a spilling breaker. Luckily, spilling breakers are far more
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