Sling your hook !
Divernet
If you go out of your way to find big fish, theres a good chance youll also find strong currents - and not always horizontal ones. Even if you dont go looking for such currents, they might just come looking for you, so it pays to know how to handle them. John Bantin explains

I WANTED A REEF-HOOK, SO I PHONED ROUND A FEW DIVE SHOPS in the hope of buying a ready-made one. My calls were not well-received.
In fact, I experienced some rather rude rebuttals, along the lines of: We certainly would not stock such an item, nor would we encourage you to buy one!
It occurred to me that I was getting the same reaction that I might expect if I asked for a shark-fishing hook or a catapult for shooting birds. These shop staff clearly didnt know what a reef-hook was, nor that its function was to preserve both the reef and the diver who might be using it.
It has to be said that the diving industry is sometimes responsible for dispensing misinformation. One idea that is often mooted is that foreign or tropical diving is akin to swimming with pretty fishes in a warm aquarium. Of course, there are places where this idea holds true, but if you like to dive with the more dramatic animals, youll need to go where they congregate, and this is usually where there are big currents.
Famous dives sites like Blue Corner or Pelelui Cut in Palau, Dirty Rock in Cocos, Darwins Arch in the Galapagos, the channels of Aldabra, Shaab Rumi in the Sudan, the Indian Ocean side of the Indonesian islands, the Coral Sea, Shark Bank in the Seychelles, and the kandus into the Maldives atolls are all subject to mask-ripping flows.
Even the south point of Dragonera Island in Majorca comes alive only once the water gets moving.
At such sites, you need to get into the water and down quickly if you dont want to miss it. If you do miss it, there is no alternative but to surface, get picked up, and try again.
This makes a case for being prepared to enter the water without any air in your BC, or being very quick to duck-dive and dump the air from your BC at the rear lower dump valve (if you have one) as you go. Either way, practice makes perfect.

BRAIN NOT BRAWN
Theres no point in trying to go against the flow. A fit man can only really sustain a swim against a current of less than one knot (one nautical mile per hour). Anything stronger demands considerable preparation and technique on the part of the diver.
Fish are much better at it, but then, they constantly practise! Humans need to use their brains, not brute force.
In Britain, divers in the tidal waters around our coast tend to go for only one option, and that is to drift with the flow. But then, if they knew of a point where the big fish loitered, things might be different. At those foreign places mentioned above, it can be quite normal to find yourself in three or four knots of flow, or even a lot more. Theres nothing aquarium-like about that!
We expect currents to move horizontally but they can also go up or down. This happens when an irresistible ocean flow hits an immovable underwater cliff. It divides left or right; sometimes it flows up and over and occasionally it goes down. (See Komodo - East of Java, December).
Gordons Rocks in the Galapagos offer a good example of the latter phenomenon, a down-current. The ocean flow hits the outer edge of the caldera of an ancient submerged volcano. It flows over the top and tumbles down the other side and in the process turns into an underwater version of Niagara Falls.
If you find yourself in such a down-current, the first thing you will notice is that your exhaled bubbles are going the wrong way - downwards. Filling your BC completely doesnt necessarily mean that you will go up. Its very frightening the first time you experience it.
So how do you stop yourself being sent down to the abyss Trying to swim up will result only in a rapid heart-rate and wasted air. You cannot swim up a waterfall, unless you happen to be a salmon. You must have the presence of mind to swim sideways out of the flow, just as you would to get out of the way of Niagara Falls.
If you are close to the wall that is causing the effect, this could be the time to deploy your reef-hook. Tying yourself off for a moment gives you time to think and consider whats happening. The flow of water wont all be going down - on either side, it will also be parting horizontally. You might not be able to see where the down-current borders sideways-moving water, but it does, I can assure you, and you need to get into that area.

GIMME SHELTER
Of course, where the current splits three or even four ways, there will be an eddy. Get yourself into that and you can relax, and take time out to concentrate on what you came for - watching the big fish that enjoy such conditions. The fast-flowing water is loaded with nutrients and oxygen, and big predators take advantage of the smaller animals that literally get swept into their mouths.
In Palau, the water sweeps up and over the reef walls. If you want to stay at the edge, watching the show, the reef hook will help you.
You can, of course, rely on gloves and cling on, but youll wreck the reef, your gloves and probably the knees of your suit too.
Sticking your hook in and belaying the metre and a half of line that is securely karabinered to a strong point on your BC will allow you to add a little buoyancy and fly in the current, with your hands free to work your camera if required.
Horizontal currents are easier to visualise. Imagine that youre out in a high wind. Yes, currents can gust too!
Ducking behind a rocky outcrop can get you out of the wind and you can do the same under water. Look for those places in which the fish seem to be relaxing.

VECTOR YOUR BODY
In Cocos, youll see whitetip reef sharks taking it easy in such places and they wont mind you joining them. Seeing all those little reef fishes apparently swimming at full speed upwards can be a sign of a down-current.
Big fish can surf on a current. They might appear to be motionless but they know how to vector their bodies so that they appear to be hovering in a lazy way.
I remember once filming salmon in a Scottish river. The bailiff who was with me kept talking about where the fish were lying, but under water I could see that they were not simply collapsed on the bottom.
They were rocketing along, even though they were getting nowhere, yet seemed to be putting in no effort into the process. I, meanwhile, had had to be tied by a substantial rope to the bridge from which the fishing experts viewed proceedings.
Few of us are as aquadynamic as these animals but I remember meeting a female diver who could do the same sort of thing. She really impressed me in the currents of Klein Bonaire as she bent her body to present a convex underside, and was able to hover motionless as a result. Its a matter of falling with style - your body is set to go down through the flow but sideways presure effectively holds you in equilibrium.
There is no way I could be supple enough to do that, but you might like to try it!
Hooked on and facing into the flow, this is when you discover whether your regulator has any weaknesses. Many will free-flow because of pressure on the purge control. Our most recent major regulator comparison (March 1998, www.divernet.com) tested for this effect, among others.
So when you have found your place, either hooked on or in an eddy, and grown tired of seeing the show, youll need a way of getting out into the horizontal current - never the up- or down-current - and getting to the surface while bowling along.
Remember that the water, and hence your exhaled air, moves along with you. Only the landscape appears to roll by.
This is when good old techniques such as using a late-deployment surface marker buoy and winder reel come in useful. How, otherwise, will the folk in the boat know where youre likely to come up
Those currents caused by the underwater topography forcing a flow to be diverted can drop off as soon as you get into open ocean. Similarly, if you work your way to the lee side, which you can do, for example, at Dirty Rock in Cocos, it will ensure that you do not go very far. But it is still advisable to carry a surface flag with you.

HELTER-SKELTER RIDE
At the Aldabra channels, it would be foolhardy to dive on an out-current. Instead, you stay outside in the flow with the fish until you decide to yield yourself to the pressure of water flowing into the atolls lagoon.
Its a helter-skelter ride and you can reach speeds of more than 10 knots in the process, but youll have to wait to read about all that in a future issue of Diver.
Ending up in a lagoon is one thing. Ending up bobbing in the ocean at the mercy of what might be a confluence of different currents is another matter entirely.
Once you hit the surface, youll need to be seen. A large surface flag on a folding flag-pole is almost essential, especially if the ocean has any form of swell to it, because you can get lost to view in the troughs. Theres nothing inconvenient about attaching one of these flags to your tank by a couple of bungee cords. You can deploy it with one hand and it can be a life-saver.
I once met a pair of American divers who carried a watertight bag of emergency materials attached to the cambands of their tanks. It was in response to a tale told to them by another couple who had spent some hours at sea while their boat searched for them. They each had a small bottle of drinking water, some biscuits, a kepi-style sunhat and a signalling mirror.
They hadnt thought of bringing a flag, however, and I suggest that they just might have got their priorities wrong.

Divernet
COPING WITH CURRENTS AROUND BRITAIN

The shallow seas around Britain are influenced by the rise and fall of the tide of the Atlantic ocean. This means that the water is usually rushing in one direction or the other, except for those magic moments as it slows down to change direction, which we call slack water.

We try to time our dives so that we are in the water during these slack periods, but as they can be very short (shorter than the duration of a planned dive) and happen only twice a day, more often than not we find ourselves diving in a current.

If youre diving a wreck, it can offer protection from the flow, but once you leave the shelter it offers, you are at the mercy of the moving water, although the low visibility often encountered will obscure that fact.

Remember, your exhaled bubbles will be moving along with you. Thats when the late-deployment SMB is crucial to your survival. The boats coxswain will need to know where you are long before you surface.

If you choose to make a drift dive, you must take an SMB with you and use it throughout the dive. Be aware that the expression drift dive can have another meaning in other parts of the world. Usually it means that the boat does not anchor or moor but drifts and comes to the divers where they surface.

Drift-diving in Britain means that the divers will be drifting with a current. If you choose to share one SMB between a buddy pair, you need to be sure that you are not separated in the murk. This is where a buddy-line comes in useful.

You clip yourselves together with a line a couple of metres long. This can lead to complications if, for instance, you choose to pass on different sides of a large rock. Simply getting entangled is another hazard associated with lines like this under water.

Other divers use a system where one operates the reel, being careful to keep the line at its shortest between the reel and the buoy at the surface, while the second diver holds on to the deployed line slightly above and to one side of his buddy.

Holding hands is rarely good enough. I know of three divers who chose to dive the Corryvreckan, a site with an unusually strong current, keeping together throughout the dive by holding hands.

Visibility was poor, but after the dive the diver who had been on the right of the group complained that the man next to him had kept trying to pull his hand away.

Yes, said the diver on the left, he kept trying to do that to me, too.

It was just that I would have liked to have cleared my ears, replied the man at the centre of the trio plaintively.
Divernet
HOW TO MAKE A REEF HOOK

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You need a strong hook with a wide jaw, the whole thing no bigger than a fist. I made mine with some 2.5mm steel rod, which took considerable force to bend into shape once mounted in a vice. If you can find a ready-made one with one end formed into an eye, it will save you considerable effort!

The point of the wide jaw is that you need to be able to insert it quickly into any small hole in the rock and the full loading is put onto that, without damaging the coral. You will also be able to disconnect the hook easily afterwards.

Attach a suitably strong line by means of an anchor-bend neatened up with a few half-hitches. Do not use a bowline - it will probably come undone in your pocket and let you down the moment you come to deploy it.

Plaited terylene line is nice to hold on to, especially when you need to drag yourself back down to the hook to disengage it, or use it for a bit of underwater rock-climbing.

Attach a suitably large, open-jawed karabiner (without any locking-ring) at the other end so that when you come to use it you can attach it to a strong part of your BC. Threading it through two D-rings and back on itself so that you pivot centrally about it proves quite comfortable.

I leave mine permanently in my BC pocket but have practised so that I can deftly deploy it should the need arise. And if I do encounter a strong current, other divers not so equipped look at me with envy!



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