January 3, 2010

The size of waves

SOMEONE ASKED ME the other day: “How big were the biggest waves you ever saw at sea?” And I had to admit that I didn’t know. As a practical matter, it’s extremely difficult to estimate the height of waves from the cockpit of a small boat in a gale. I was always more concerned with wondering if we would get over a swell before the top of the wave broke and came thundering down on us.

Sailors’ accounts of wave heights are traditionally taken with a pinch of salt because there is a natural tendency to exaggerate, but there are some reliable records that indicate that wave heights of between 40 and 50 feet are not uncommon in heavy gales in some oceans. You need only see those pictures of the surf battering Hawaii, or the Oregon coast in winter, to believe that.

And, because wave trains occasionally coincide so that one wave rides on another’s back, single waves can be much bigger. A wave 80 feet high was observed from the steamship Majestic in the North Atlantic on December 29, 1922. Meteorological authorities consider the sighting authentic.

But if you’re out there in a small boat, it’s not the height of the wave or swell that bothers you, it’s the height of the breaking crests, especially those wicked crests that plunge, rather than spill, down the front of the wave. It’s safe to assume that in a whole gale of 48 to 55 knots in the open sea, many breakers of 6 feet in height will be encountered. Six feet might not sound much, but believe me, 6 feet of plunging breaker contains enough energy to do an awful lot of damage to a small sailboat.

So, did I ever encounter a 6-foot breaker? Heck, I can’t really say yes to that, either. I probably did, more than once, off the Cape of Storms, but the occasion is not one where you get out the tape measure to verify the height. There are other ways to calculate how frightened I was, and they registered 10 out of 10.

Today’s Thought
Let him who knows not how to pray go to sea.
— John Ray, English Proverbs

“I see Old Moneybags finally got hitched to that chorus girl he’s been chasing for so long.”
“Yeah, he spent a fortune on her, so he had to marry her for his money.”


S/V Cape St. James said...

Did you write the artice for 48North 20+ years ago dealing with old sailing terms and how they came to be? I'm trying to find that article.
Appreicate any help.

John Vigor said...

Hi Fran:

No, Fran, my wife says it wasn't me. Her word is more reliable than mine. Even if I had written it 20 years ago I wouldn't remember it now. Good luck with your search.

John V.