I kinow of at least two explanations for "sleeping", or simply unexpected,
waves. One is the constructive interference event discussed here, in which two
waves from difference directions happen to add up when they collide. That's
basic arithmetic and is common near hard reflective shorelines such as a dam or
The other source, which is probably what "sleeper" refers to, results from a
very wide but low wave rollin' across the deep ocean onto a shallow coastline.
Some deep-water ocean waves can be hundreds or thousands of meters long but just
a few inches high, sliding unnoticed beneath a ship. But think of the volume and
1/2mv**2 energy contained in that bulge, then try to imagine its shape when it
piles up on a shallow shoreline and dissipates all its energy in a suddenly
confined space and time. At its extreme it's called tsunami; its little brother
is called a sleeper. Same principle, different scale. Weather satellites can now
measure these 2"-inch-high, mile-long waves (or a 2"-high million-square-mile El
Nino tilt of the ocean), and are getting much better at recognizing both tidal
waves and the Southern Oscillations of El Nino/La Nina much sooner than before.
Disclaimer: the 2" figure comes from fuzzy memory, but I'm pretty sure that was
the resolution achievable these days.
To reply directly, remove the SpamDam.
> I'm pretty sure this refers to a "rogue wave" or an unusually large
> wave that seems to come out of nowhere.
> There have been several instances of people (fisherman primarily)
> being swept off (pounded into) the rock jetties and breakwaters in
> the So. Calif. area. Many of them drowned or were seriously injured
> when a large wave broke over the breakwater.
> They may have been fishing there for hours, perfectly dry, and then
> this one big wave breaks over the jetty and they are suddenly in the
> water, or worse battered over the rocks.
> I've seen the same warning, primarily on the jetties and breakwaters
> where this has occured in the past.
> You went all the way from the Bay area to So. Calif. and you couldn't
> find anywhere to sail??? What's up with that?
> Several sites in the SF. Bay, Santa Cruz, San Luis Res., Lake
> Isabella, Santa Barbara, Cabrillo Beach, San Diego.
> Lots of places, many of them with some sort of rental gear?
> > > > I just got back from my vacation to CA. I Went from SF down to
> LA. No windsurfing. However, while running along the beach front in
> Cambria there was a warning to swimmers which, among other things such
> as rip tides, mentioned "sleeping waves." Does anyone know what this
> is? Thanks.
> > > > Ben
> > > I'm no surf expert, but a sleeping or "rogue" wave is one that
> > > builds rapidly with no precursive set or indication.
> > > --
> > > Craig (Go Short or Go Home!) Goudie
> > > Sailing the high desert lakes of Utah on my:
> > > RRD 298, Starboard 272 and Bailey 8'6" with
> > > Naish Sails and Rec Composites Fins
> > > Sent via Deja.com http://www.deja.com/
> > > Before you buy.
> sailquik US 7011
> Sent via Deja.com http://www.deja.com/
> Before you buy.