Understanding local tides and currents in Gili Islands

[IWantToBeAFish]

Hi all,

Im currently working as a DM in the Gili islands. Guiding is fun with a good range of dive sites but some of the better sites are very dependent on the currents and tides. There is constantly difference of opinion about whether we should venture to a site on a given day and I'd like to be a bit more scientific.

Sadly this seems hard in the area - tides seem unpredictable and can go from high to a bit lower to high again all within a few hours before a massive low tide just a few hours after that.

Surface conditions and deep currents have little correlation.

The islands sit in the Lombok straight which serves as one of two main through flows from the pacific to Indian oceans.

My questions:
1. Does anyone have any experience of this area and has tried to figure this out before?

2. Is a rising tide and different to a falling tide with regards effect on currents?

3. What could be the likely contributors to high/low tide period irregularity?

Thanks very much in advance

 

[IWantToBeAFish]

A quick bump - anyone able to help at all? Thanks

 

[Kevster]

Working as a DM , your profile states 0-24 dives??
You may already know all this info.

1.Tidal charts should be available on the web for Lombok. Just google it. If not maybe try looking for Bali tidal charts.

2. Will change the direction of the current but not necessary the strength (just depends where you are on the tide curve). To avoid current you would want to dive near the max/min point of the curve where the rate of change is small.
3. Sun/moon alignment, moon position ,bad weather, water temperature,High pressure /Low Pressure storms in the pacific may impact the water movement around lombok/bali.
4. Underwater topography may impact deep currents, water movement.

As you say due to the vol of water the currents may be unpredictable.
Check out the following link for detailed info.
http://www.tos.org/oceanography/archive/18-4_ray.pdf

 

[frogfish]

If you work in the Gilis you should be able to get expertise from local experienced DMs ?

 

[buiszie]

Currents around the Gili Islands are strange, u could have a look at Apenam. but there is 1,5 delay in the curves of the tides. Local dive guides should know the tides. During july and august there will be strong currents and waves in the afternoon.
another easy tip dry season currents go from north to south, rain season the currents go from south to north.

If u are a dmt ur duty is to check the current before ur customers enter the water. u take the discision if the current is ok or too strong for them. during ur dmt course u should learn how to check a current, and thats it is no shame to abord dives for safety reasons.

 

[IWantToBeAFish]

Thanks very much for the replies! Have updated my profile accordingly with actual status. The local dive guides I work with have good intuition but cannot explain why - something I'm trying to fill in. Tide charts I've tried so far have left me a bit perplexed even when I try and adjust them to our timing, we appear to get strange anomalies. Of course, we always do a current check at the site before dropping and adjust drop point or dive site entirely in accordance with what we find. I suppose the scientist in me would love to be able to know with good accuracy before we even get there

Ill check out the tide charts for Apenham for sure and that's a really interesting point about the reversal of the N->S current in the rainy season.

Thanks all!