Hoe duik je het best tegen de stroming ?
| Geplaatst door: | Ivo Simons |
| Artikel gevonden op: | https://divernet.com/2018/08/23/swim-like-a-cave-diver/ |
| Datum: | 27-08-2018 om 08:27:15 uur |
| Bezoeken: | 545 |
SWIM LIKE A CAVE DIVER
Sometimes you have little choice but to go against the flow, but battling a current can be exhausting. SIMON PRIDMORE offers some tips that can make the prospect that much easier. Photos by ANDREY BIZUKIN
A diver moves across the sand with fins nice and high.
WHEN WE DIVE IN INDONESIA, we often find ourselves fighting strong currents. You might be wondering why we don’t just turn round and go with the flow instead.
Well, often, on a sea-mount perhaps, or at the ocean-facing apex of a wall, if we go with the current we’ll find ourselves floating in a fish-free desert.
However, if we push against the current for a while, to the point where the wall turns or where the sea-mount faces into the flow, that’s where we find all the fish: millions of them. They love current.
Some, like trevally and barracuda, will be swirling and twisting together in enormous schools, collectively resisting the current’s pull, surfing the current like birds of prey riding on thermals.
Others, such as fusiliers and snapper, will be coursing up and down and round and round, crazily chasing each other’s tail in a wildly chaotic fish race.
So this is where all the action is, and this is where we want to be, hanging at the end of our current-hooks, watching the show. But to get there without exhausting ourselves, or using up all the air in our cylinder, we have to deploy a few techniques, many of which were originally developed by cave-divers.
Appeared in DIVER August 2018
USE THE CONTOURS
When you dive against the water flow in a flooded cave, you don’t just swim down the middle of the cave. That’s where the flow is the greatest.
You stay close to the wall and look ahead at the contours of the section of the cave towards which you’re swimming. Then you plan your route to make sure you use those contours to shelter from the flow as much as possible.
The same technique applies when you’re swimming against the current across a seabed. Marine topography rarely consists of flat bottoms, straight lines and smooth curves. Every reef has a multitude of outcrops, slopes, ridges, canyons, bommies and other inconsistencies that you can use to your advantage.
The contours of the reef can help to make your journey across it less energy- and air-sapping. For instance, if there is a ridge or bommie in front of you, this will at least partly shield you from the current.
Just keep low, below the height of the ridge, or position yourself in line behind the bommie, and you will be able to make progress more easily.
As you get closer, look beyond the ridge or bommie to find the next obstacle you can use to hide behind. Even a slight deflection can diminish the force of the current you’re facing.
A diver swimming straight down the middle of a cave – not the best way to go against the flow.
If there are bommies or boulders close together, the contraflow will be much higher through the narrow channel between them, so choose a path where gaps between obstacles are wider.
If you have to go through a narrow gap, stay close to the side rather than passing through the centre. You will find it much easier. The same applies if you take a swim-through from one side of the reef to the other, and the current is against you. Stay close to the side of the swim-through and you won’t have to kick so hard.
GOOD POSITIONING
You’ll make better headway against the current when you adopt the horizontal, trimmed posture of a cave-diver, with all your equipment configured in as streamlined a way as possible; everything tucked away and nothing dangling.
Your arms should be close to the body, either folded to your chest, kept tight to your sides or stretched out in front of you, with fingers interlinked or pressed together, to carve your way through the water like the prow of a ship.
In this way, you present the smallest profile possible and the least-possible resistance to the force acting against you.
STEADY BREATHING
Concentrate on maintaining an easy, long breathing pattern with long inhalations and, most importantly, long exhalations.
This is crucial because, with the increased expenditure of energy and your mind’s focus fixed on the ultimate goal of all this effort, you can all-too-quickly lose control of your breathing and start gasping.
This creates carbon dioxide build-up and leads to increased stress and anxiety, which can easily turn into panic.
The best way to prevent this happening is to develop your aerobic fitness, as a long-distance runner or swimmer would, and, during the dive, ensure that you stay attuned to the rhythm of your breathing and stay alert for any changes.
FINNING TECHNIQUE
The frog kick is the perfect fin-kick for a long steady push against a current, and helps to conserve energy during a long swim. The kick is identical in form to the leg movement when you swim breast-stroke.
To minimise disturbance of the environment through which they’re passing, cave-divers use a modified frog-kick with their knees bent at 90°, and generate power only on the inward stroke.
On the outward movement, the fins are simply allowed to drift out to their full extension before being brought together again more quickly.
When swimming against a current in the open ocean, you can use the power frog-kick, where both the outward and inward strokes are power strokes and more force is generated. This is the kick of a competition breast-stroke swimmer.
HAND & ARM TECHNIQUES
It is not entirely true to say that divers never use their arms and hands to swim. Cave-divers sometimes deploy a couple of particular hand and arm techniques when they need to make forward progress and save energy in places where the flow is against them.
You can use the same techniques to help you battle a current in open ocean.
KICK & REACH / PULL & GLIDE
On a rocky seabed, you can use a technique called “pull and glide” or “kick and reach.”
This involves stretching one hand forward, grabbing onto a rock, then propelling yourself forward with a strong single fin-kick to grab on to another rock with the other hand, and so on.
You’re like a rock-climber moving up a wall, moving from handhold to handhold, except, of course, that you’re moving horizontally, rather than vertically.
You have to deal with a strong current; the rock-climber has to deal with gravity.
Of course, you need to make sure that the rocks you grab are really rocks and not sponges, corals or stonefish, and it is best to copy what the cave-divers do and grip with your palm rather than your fingertips, for increased traction.
Keep your fins high off the seabed as you kick. Even the barest-looking rocky seabed is home to marine life of some description.
FINGER-WALKING
Over a sandy seabed, you can use a similar technique called “finger-walking” to help you sustain momentum and support your finning efforts.
You just poke one index finger in the sand, then kick and reach forward with your other hand and plant your other index finger in the sand.
Then, keep moving over the seabed, with your fingers walking you across as you kick.
Again, keep your fins up above your body-line to make sure they don’t come into contact with the sand.
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