JimH wrote:

Interesting. I went to my Chapman's to look up their definition of chop:

"The confused water action found at places where tidal currents meet is
called a chop, a term also applied to small, closely spaced waves resulting
from wind action on small bodies of water."

So it looks like a 5 foot chop can be the same as 5 foot seas.

I don't boat on the ocean so I was not familiar with the first part of the
definition. ;-)


Most boats can easily handle a 5-foot, 10-foot, or even larger ocean
*swell* if the waves are far enough apart (defined as a "period"
between swells) that they aren't too steep. You just go uuuuuuuup,
pause a second, and then go doooooooown. No big deal, unless you're
subject to sea sickness.

You certainly experience chop on the lake where you boat, as it is a
much shorter and steeper wave form created primarily by wind. With
enough fetch, even a lake of moderate size and certainly any of the
Great Lakes can become pretty nasty in 30-knot conditions.

Before you put Chapman's away, look up the Beaufort scale. My latest
copy is a 1985 edition and the scale is on page 327, but if you have
another edition it may be somewhere else in the book.

Look down the chart to Force 7 winds:

28-33 knots (32-38 mph). "Near Gale". "White foam from breaking waves
begins to be blown in streaks" BOATS REMAIN IN HARBOR; THOSE AT SEA
HEAVE-TO.
Effects observed on land: Whole trees in motion, resistance felt when
walking against wind.

The chart refers to waves of 4-6 meters at Force 7, but again those
would be swells.
There's no such thing as 18-foot chop- or if there is I never hope to
see it. :-)

Capable of structurally surviving such conditions and choosing to be
out in them are two different concepts.

Chop is like the fish somebody caught last week. The more times the
story of a stormy passage is told, the higher the waves seem to become.
There are probably a lot of guys who tell stories about 8-foot chop
that have never seen 5-footers. In places like Puget Sound or the
Chesapeake chop is usually very steep. Imagine hitting a 5-foot "speed
bump", and then imagine hitting another one every several seconds.
5-foot chop breaks just below the anchor pulpit on my 36-foot tug.
Those are some nasty and uncomfortable seas. 7-foot chop breaks over
the rail and floods the foredeck, and being out in that stuff is
insane.