How to Determine the Speed of Currents
“That was crazy current! We are lucky to be on boat again! Did you see how strong it was? I was nearly not able to stay on the reef.” I’m sure every dive guide in Bali must have hear or made such a comments him self coming from diving. People like adventure and even better they like to talk about it. Bali has amazing diving and sometimes amazing currents too. But are they really always so strong? How can we actually tell the speed of moving water.
Even many divers come from dives full of excitement and loudly talking about “3 knot” strong current the rate of flow is actually difficult to judge with precision and the emotional side of an experience sometimes nicely helps with and exaggeration. Same like my sharks are never smaller than 5 meters, seriously people! Well after millions of years of adaption to all sorts of current experiences the best judges of its strength are definitely going to be the fish. After all they have not need of boosting up the story because as you could see in Finding Nemo they seems to prove them selfs little differently.
If you want to use little fish as your help in guessing the speed of currents here is scale which was developed by Wally (diver with over 10 000 dives) and many other divers over long years of diving experiences.
- NO CURENT: the small fish are swimming happily in every direction and they are distributed both vertically and horizontally.
- LIGHT CURRENT ( to 1 Knot): the small fish are aligned and all facing up the current. If you can see them still up in the water column the current is around half knot. If the schools are low and wide close to the coral, the current is close to 1 knot.
- MEDIUM CURRENT (1 to 2 Knots): The small fish are now hovering in schools spread like a mat over the coral and finning madly. The current of this strength begins to show on the behaviour of a big fish too, as they face the current and tend to concentrate behind bommies or in other lee areas.
- STRONG CURENT (2 to 3 Knots): In the current of this power the small fish are all hiding among the branches of the coral. The big fish are gathered at sheltered areas or close to the bottom. But anyway by the time the current approaches 3 Knots you will not need fish as an indicator. If your mask fluters and threatens to fly away and you regulator free-flows, you are at three knots : ). You better hang on to something and face the current.
In a case you are drifting or being blown around reef by a strong current you will see most of the fish hiding, but not all of them. Look around bommies or in natural hollows in the reef surface and if you see fish swimming open there you found the lee or shelter where you can take a nice break and look little around. Sometimes is possible to find a place which looks totally identical to the place with strong current but the fish swim there in water column like nothing was going on in there. This is the place where the current shifts and the place where you wanna be yourself.
Hope this will be little help with your future current adventures.
Thanks to David Pickell and Wally Siagan whose book was the source of information.