The following is a safe boating message from the National Safe Boating Council and the National Weather Service for this year’s National Safe Boating Week.
Wind and waves affect all types of boats so it is important all boaters know some basic facts about winds and waves.
Wind over water is usually stronger than over nearby land. Wind is the main factor in wave development and in general, the stronger the wind, the larger the waves.
Individual waves are measured from trough to crest. Seas are the combination of both locally generated wind waves and distantly generated swell waves and are expressed in the terms of the Significant-Wave-Height, the mean or average height of the highest one third of the waves. It approximates the value an experienced observer would report if visually estimating sea height. When expressed as a range (for example…. seas 3-5 ft), this indicates a degree of uncertainty in the forecast and/or expected changing conditions (not that all waves are between 3-5 ft).The danger presented to a vessel is a function of wave steepness as well as wave height and is unique to each vessel. In general for small vessels, for a given wave height the danger increases as the wave period decreases.
“The seventh wave of the seventh set” An old fisherman’s tale? Perhaps, but it does serve to highlight that wave and surf conditions are not always constant. In open waters, the occasional wave may be twice that of the surrounding sea. There are occasional reports of “rogue” waves of an even greater ratio. Near shore, waves are even less predictable. So-called “sneaker waves” can grab the unwary who venture too close to the unpredictable sea. Mariners may be drawn too close to the surf zone during periods of relative calm. Proceed cautiously and always be wary of this not uncommon phenomenon, especially in areas where breaking surf is known to occur or appears likely.
Winds and waves can change quickly in speed, direction, and steepness so it is important you include a marine forecast in your preparations for boating.
This message was brought to you by the National Weather Service and the National Safe Boating Council. Visit the National Weather Service on the web at http://www.weather.gov/ and the National Safe Boating Council at www.safeboatingcouncil.org