[Paddlewise] "Sneaker Waves"

I was over in Seattle picking up doodads for the mutha-ship and managed to
get a Latitude 38 magazine from San Francisco. All Bay Area and most
cruising sailors are familiar with Lat 38 but kayakers may not be. It's
geared to the Bay Area sailors and to the cruisers mainly in Baja California
and the articles are usually well written and authoritative by people who
have not only "been there" but are very likely "out there" right now. I
should know... I was one of them back in the 80s. <grin>

This issue (current for this month) had a short discussion on "sneaker
waves" in the Letters section that I thought would be appropriate for
paddlers.

Sneaker waves have been around forever. I've had a few friends get hit by
them. They occur along the Pacific coast of North America mainly in the
winter and spring months and seem to be caused by long-period waves
generated by storms in the western North Pacific Ocean. These long-period
waves behave somewhat like Tsunamis in that they carry an enormous amount of
energy and they are almost unnoticed in deep water but release their energy
in shoal water or around rocks.They are not well understood yet and there is
a certain amount  of controversy regarding what, exactly, they are. One
thing is fairly obvious though... they are very dangerous to boaters in
shallow coastal waters.

And that is where paddlers come in.

Sailboaters and other coastal cruisers generally don't get into shallow
water until they are approaching land either to enter a harbor or anchorage
or are in the process of departing. Kayaks, on the other hand, spend a lot
of time in shallow water because that's where almost all the fun is.

Basically what paddlers on the west coast of North America need to be aware
of is wave period. Check offshore wave-rider buoys and if the swell period
is greater than about 5 minutes be very cautious when paddling in shallow
water exposed to the open ocean. If the swell period rises to 14 minutes be
on constant alert.

A story to illustrate the nature of these is about cruising friends of mine
who were approaching an anchorage north of Morro Bay. It was getting dark
and the seas were flat calm with a long rolling swell. As they were motoring
in they passed a well-marked rock (giving it what they thought was plenty of
room) when their boat was suddenly picked up by a huge sea and washed over
that rock. This was in a 38-foot, 25,000 pound cruising sailboat!!

No one was injured but a lot of water made its way below and they spent an
extra week in Morro Bay drying things out. It also resulted in a rule we all
subsequently followed: all companionways, hatches, and portlights are closed
and dogged down tight and all crew on deck wears PFDs and are clipped into
the lifelines.

As I said earlier, there is some controversy as to the exact nature of these
waves. This is partly because there is often only one wave in what otherwise
might only be relatively calm water and ocean scientists don't like the idea
of one wave rising up from nowhere. Nevertheless, "sneaker waves" are well
documented even if they are not well understood. If you paddle the open
ocean along the west coast of North American (and, for all I know, any
coastline open to a fetch that extends thousands of miles) watch for
long-period swells and be ready any time you are in shallow water or around
reefs and rocks.


Craig Jungers
Moses Lake, WA
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