Public Information Statement
Issued by NWS Portland, ME
NOUS41 KGYX 212215
PUBLIC INFORMATION STATEMENT...NATIONAL SAFE BOATING WEEK
NATIONAL WEATHER SERVICE GRAY ME
615 PM EDT TUE MAY 21 2013
...THE NATIONAL WEATHER SERVICE and NERACOOS (NORTHEASTERN REGIONAL ASSOCIATION
OF COASTAL OCEAN OBSERVING SYSTEMS) CONTINUES TO OBSERVE MAY 18th
THROUGH 24TH AS NATIONAL SAFE BOATING WEEK...
...Wind and Waves...
The following is a safe boating message from the National Safe Boating Council
and the National Weather Service...reminding you that National Safe Boating Week
is May 18TH through May 24th.
National statistics in 2011 indicated that 377 boats went down in calm seas
nationally. However...287 crafts also sunk under choppy...rouch or very rough
conditions during this period.
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 TO 5 ft)...this indicates a degree of uncertainty in the
forecast and/or expected changing conditions. 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 from the National Safe Boating Council was forwarded to you by the
National Weather Service and the Northeast Regional Ocean Observing