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Tips
for Diving in Surge
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Step
1: Back Off
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Surge, like
the waves that cause it, comes in sets of
stronger flows, and lulls of weaker ones. If
your problem is to approach the boat ladder,
back off a few yards and watch the situation
until you can read the rhythm of sets and
lulls. |
Step
2: Don't Fight It
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Even moderate
surge is stronger than you are. Don't
exhaust yourself trying to move forward
against it. Instead, hold on to something (a
current line, an anchor line, a rock) when
the surge tries to carry you backward, and
ride it when it carries you forward. Nothing
to hold on to? Fin steadily forward just
enough to remain stationary. Backward and
forward flows are about the same and will
cancel out. |
Step
3: Timing Is Everything
Wait for a lull (a
period of weaker flows) to make your move. Exiting
the water? If you time it right, you can ride an
inflow to the ladder or rock, hang on during the
outflow, and climb out during the slack water before
the next inflow. Going through a wreck opening or
swim-through? Likewise, ride the inflow to the edge,
hang on during the opposite force, then use the lull
and inflow to swim through and away from the opening
where the surge is strongest. Be cautious on your
approach. It's better to fall short of the ladder or
opening and have to do it again than to be thrown
against it.
When
Surge Is Strongest
- In
shallow water. Usually you can avoid
surge by going below 10 or 20 feet. (But it
depends on the size of the waves.)
- When
waves are big. Big surf means surge is
not only stronger but reaches deeper.
- At
narrow openings. Remember the venturi
effect? Surge accelerates in gaps between rocks
and through openings in wrecks.
- Around
stationary objects. When water has to
make a detour around a rock outcrop or a wreck,
it goes faster.
Why
Doesn't the Boat Move?
You and the dive
boat are both floating. How come the surge moves
you but not the boat? Actually, the boat probably
does move, especially if it's small. But the
heavier it (or any object) is, the more inertia it
has to resist the surge. And it may be big enough
to span several waves at once--in which case
inflows and outflows cancel each other and it's as
immobile as a rock. Plus, if the boat is at
anchor, the anchor line restrains the boat's
movement.
By
John Francis
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