Boating and Sailing.pdf - Moja ladja

Chapter 15: Weather You Like It or Not
Beaufort Wind Speed
Number (in Knots) Description Effect on Water
10 48–55 Storm Waves 20–30 feet,
sea heavily streaked
11 56–63 Violent storm Waves to 45 feet, sea nearly white
12 64–71 Hurricane or extremely Waves over 45 feet, sea compleviolent
storm tely white, visibility near 0
By the time SCAs would be posted, you’d be looking at 4- to 8-foot waves in areas with a
long fetch. That’s a whole lot more wave action than most leisurely weekenders want to
deal with, even though it’s not necessarily dangerous in a larger yacht.
In reality, most boaters don’t want anything to do with steady seas over 3 feet in boats that
are 20 feet long or less, and as you note from the scale, winds of just over 10 knots might
bring these in exposed areas.
A Personal Experience
I’ve only had the opportunity to experience Force 12 winds once on the water, and that was
in the completely enclosed harbor at Hopetown in the Bahamas—not a hurricane, but an
amazingly violent summer thunderstorm that blew at what locals said was near 100 mph for
about 10 minutes before subsiding.
It was an impressive sight, even inside the harbor where there was not enough fetch to create
any wave action. The water went white as snow, and about half the anchors and moorings
in the harbor let go.
Dozens of yachts and sailboats were soon caroming off each other in a race toward the
downwind side of the harbor. Skippers were pushing off, starting their engines, fighting
with their lines—it was general chaos, but the saving grace was that it was so brief. There
was no damage except for a few bent railings, but it was an exciting interlude. (That’s what
we called it afterward, “exciting.” When we were in the middle of it, we were all scared to
death.)
Land and Sea Breezes
215
Land and water heat up at different rates. This causes a pressure differential between the
two, and breezes result if no stronger weather system interferes.
During the daytime, the land heats up faster and the air rises and loses density. As a result,
the denser, cooler air from the sea blows inland.