I fought to regain the surface, but found I
couldn't get my head above the white water to breathe. I could feel panic
rising until, fortuitously, my feet found bottom, dragged along a bit, and
slowed my progress toward the shore. The breaker moved on, and I found myself
in solid water once more, able to rise to the surface and breathe.
Some time afterward I realized that things
don't float properly in water that is full of air bubbles. And by things, I
mean people and boats. I know now why body surfers dive underneath the white
water of oncoming breakers and emerge in the solid water behind them.
The simple fact is that aerated water is not
as dense as normal water and will not offer the same support to bodies floating
in it. Just as a boat will float lower in fresh water than in salt water, which
is denser, that same boat will float lower in aerated water, perhaps even
dangerously lower, depending on how much freeboard she has.
But my lesson in seamanship came when it also occurred
to me that a boat's rudder is less effective in water that's less dense, which
explains why a sailboat's helm goes dead when a wave breaks under the stern and
throws her forward. It's a nasty feeling
when she's about to broach and you can't get her to respond to the helm.
The answer, as I found out, is to slow her
down with drogues or warps streamed aft, so that she is not carried along for
any distance with her rudder in the breaking, foamy water. Let the breakers
overtake you as quickly as possible, so that you get your steering control back
before she can make mischief by turning broadside-on.
The same rule applies to boats operating in
any white water; that is, water filled with bubbles of air, especially if you're
coming in to a beach through lines of surf in a dinghy. If you don't have the engine power to stay
safely on the back of a breaker all the way in, you must slow down and let each
line of breakers overtake you as quickly as possible. In a boat powered by oars, it's often best to
turn and face out to sea, backing in slowly and then pulling forward just
before the next breaking swell arrives.
Sometimes, if you have enough line,
it's possible to drop a light anchor and let the line run, snubbing it as
new breaker arrives.
There may be unexpected danger, too, in areas
where strong tidal currents clash or run over rippled bottoms, causing the sea
surface to bobble and dance. This can
aerate the water so that a boat entering the area floats lower, and loses grip
on its rudder and propeller.
So watch out for white water. It's not
something we think about often, and it sure looks innocuous, but those pretty
little bubbles can spell trouble if you don't know the science behind them.
Today's
Thought
"Wouldst thou,"—so the helmsman
answered,"Learn the secret of the sea?
"Only those who brave its dangers
"Comprehend its mystery!"
— Longfellow, The Secret of the Sea
Tailpiece
What do you call a fish with no eyes? A fsh.
(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)
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