Ethical WickedSafe Diving in Strong Currents
It is highly advisable to be prepared in order to achieve safe diving in strong currents rather than become caught unawares and frightened and possibly endangering yourself and your diving buddy. Currents carry in food (plankton) to areas of the reef which in turn attracts fish and other animals that feed on fish, thereby making the reef a vibrant and lively dive site to explore. From our Komodo Dive Center we can encounter extremely strong currents and we are very cautious about how and where we dive.
It can be difficult to judge currents, but there are some indicators, which will tell an observer the speed of the current. Fish react according to how strong the current is. Some seek shelter, others thrive in strong currents. Look at small schooling fish like Anthias or Basslets and watch bigger fish such as Mackerel or Trigger Fish, to tell you the speed of the current.
Light current (to 1 knot):
The small fish are all finning against the current and are hovering close to the coral, the current is closer to one knot. You will probably be able to swim against this kind of current for a short period of time.
Medium current (1 to 2 knots):
The small fish will be hovering in a school spread out just barely above the coral and finning furiously. A current of this strength affects the behavior of the larger fish as well. They face the current and tend to gather behind coral heads or in other lee areas (lee – out of the wind / current). Most fish will now swim against the current, so if you do a drift dive, schools of fish will come towards you. This speed of current is difficult to swim against.
Strong current (2 to 3 knots):
In this kind of strong current, the small fish will have disappeared, because they are all hiding among the branches of the coral. The big fish are gathered in lee areas, or very close to the bottom. On a dive in this speed of current you may not be able to stop and swim against if you want to look at something close up – so best to just go with the flow.
Very strong current (3 knots):
With this speed of current, you won’t need the fish as an indicator anymore. You will either be swept along on a very fast drift dive or hiding behind a coral head. If you turn to face the current there may be some risks – your mask may fly off or your regulator will start to free-flow.
Too strong current
Anything over 3 knots is too strong and too dangerous to dive.
Different Types of Current
As winds blow across the ocean, they pull on the water’s surface, and the buildup of energy forms waves. If the wind blows fast, for a long time and for a long distance in the same direction, large waves form. Waves break when their bases hit the ocean floor and they become unstable, toppling over onto the shore.
The energy released when waves break on the beach creates longshore currents. When waves approach the beach at a 90° angle rather than head on, part of the wave’s energy is directed perpendicular to the shore and part of it is directed parallel to the shore. The parallel energy creates the longshore current, which runs along the shoreline. If you’ve ever been swimming in the ocean and felt the ocean tugging you farther down the shore, then you’ve felt the impact of a longshore current.
Rip currents are another type of coastal current that form where underwater land formations prevent waves from flowing straight back out to sea. They are the residue of waves that have already crashed while funneling out of a narrow opening, like a break in a sandbar, with great force. Imagine the great volume of water that rushes out of the bath when you pull the plug and you get the general idea of a rip current.
The type of curent we encounter the most frequently is one caused by tidal flows. In offshore locations like the Similan Islands, these currents are simply the water coming in during high tide and flowing out during low tides. In Komodo the currents are the actual tidal flow of the Pacific into the Indian Ocean and vice versa. As such, these currents tend to be much stronger just after Full and new moons whent he gravitational pull is the strongest. These currents can be predicted and understood by experienced divers and guides.
Another type of coastal current called upwelling occurs when winds displace surface water by blowing it away and deeper water rises up to replace it. The opposite process, downwelling, occurs when wind blows surface water towards a barrier, like the coastline, and the resulting accumulation of water forces the water on top to sink. Both of these processes can occur in the open ocean as well.
Useful Tips for Safe Diving In Strong Currents
An understanding of safe diving in strong currents is important as currents can be intimidating for divers because they are unpredictable and both physically and emotionally demanding as the natural survival instinct kicks in to fight against it.There are steps you can follow to ensure your safety and comfort when diving in strong currents.
•. The first priority is to check for currents before even getting in the water, look for current patterns on the surface and perhaps drop a drift line to see if there is any movement in the water.
•. A detailed dive briefing should always precede a dive involving strong currents; it will prepare you for the conditions you may encounter and provide the protocols for dealing with them.
•. If you do a free descent into currents – make sure you are thoroughly briefed and all parties understand what to do in case of separation. As it will be during this initial entry and descent that chances are highest for seperation – listen very carefully to the briefing given by your dive guide.
•. If you plan to dive in a strong current, it’s advisable to opt for a drift dive if possible. However, you need to ensure that the boat master can spot the divers on the surface and can have the boat brought around to collect you at the end of your dive. Therefore it is very important that you carry some sort of Marker Buoy and signalling device to make sure the support boat can see you upon surfacing. A whistle attached to your BC could also be useful in such a situation. We also recommend a divers mirror for getting the attention of the boats
•. If you know you are going to dive in fast currents try not to overload yourself with too much dive equipment and scuba accessories like large underwater cameras and underwater torches. What you may want to carry is; a surface marker, a buddy line to avoid separation (however it could become caught up on coral), a reef hook an great way to stay rooted in one spot as you wait for other divers to catch up or just stop and watch the passing life. This blunt hook about 10cm-long is attached to a 2m long line clipped to the diver and can be slipped into a piece of dead coral or a rock crevice.
•. If you’re not planning a drift dive, always start the dive by swimming against the current, time the dive carefully and plan your turn around time depending on the speed of the current. Stay close to the reef wall or sea floor when swimming in the same direction as the current. The current is almost always lighter at the bottom near the sea bed, so if you need to slow down or wait for the group to catch up with you, go lower and hover close to the bottom. If you find yourself pulled into an unexpected flow. turn yourself up horizontally to make become as streamlined as possible and try to cross it diagonally by swimming upstream of your destination.
•. Pace your breathing and keep a close eye on your gauges. It’s easy to lose track of both your depth and air consumption when you’re riding a fast current. Be prepared to inflate or dump air quickly if you get dragged down or up. If caught in a down current, try to get as close to the reef as you can and tuck yourself behind a ledge, be prepared to dump air from your BC quickly as soon as you get out to avoid ascending fast.
•. Streamline. Hanging, excessive equipment can be a burden on a dive in a strong current. You will get the best from the dive if you stay as neutrally buoyant and streamlined as possible. IF directed by your dive guides – wear a good pair of gloves in case you have to grab on to rocks and dead coral against a current (however avoid touching anything unless absolutely necessary). AS currents can be strong – this may not be a viable option. Always listen to the directions given by your dive guides. Remember that dangling arms create drag, so tuck them in close to your sides or behind your back. Also ensure that you are properly weighted, added weight will make it difficult, if not impossible, for you to achieve a streamlined swimming position in the water. Divers who are properly weighted can easily swim in a position that aligns their fins directly behind their head.
•. Always dive with a computer. If you find yourself being swept up or down by a strong current, your dive table calculations will be meaningless. In a strong current there is a chance that you can lose your dive buddies, so don’t rely on someone else’s dive computers.
•. Stay close to the reef. You may need to take shelter from the current or find a place to hold on to. Try to only hold on to dead coral heads or other areas without life! be careful not to come into contact with stinging hydroids.
•. Watch the coral cover – if there are table corals and acropora corals it is probably an area where currents are not so strong. This is a good place to descend and ascend. Where there are a lot of sponges, tube corals and whip corals there is a strong current most of the time.
•. Watch your bubbles and those of your fellow divers to see where there are downcurrents or whirls. This should give you adequate time to hold on quickly. But remember, don’t hold on to sponges – they snap off easily!
•. Look behind corals, or in natural hollows in the reef. lf there are fish swimming around, you have found a lee, where the current is lighter.
•. If you are an inexperienced diver, don’t attempt strong current dives unless a certified dive instructor or a more experienced diver than you acts as your dive guide.
•. Finally, listen to those experienced in the areas you are diving! Your dive guide and the captain of the boat will advise you on when it is safe to dive a certain dive site and more important, when not to dive there. There are times when there is no place to dispute the opinion of your dive guide and your captain and calling off the dive is an acceptable and recommended course of action to keep you safe and ready to dive another day! In almost all situations there are optional dive sites and there is no “must do ” dive sites!
