Thursday, 13 September 2012

Dive 2 – Sha’ab Marsa Alam

Does Diving with Nitrox make a difference?

My tanks are filled Nitrox and gradually over the week, the mix increases in strength (from about 27% at the start of the week towards 34% at the end). If you are diving repeatedly there is a danger of nitrogen build-up and surface times between dives have to increase in order to compensate. Also a dive becomes a decompression dive quicker if you are diving on air than on Nitrox. For one dive, I wore two dive computers, one set to 30% Nitrox and the other to 21% (i.e. standard air).

Does Nitrox make a difference

30 minutes into the dive after diving to a depth of 24m, (although I was now only at 14m), the dive computer set for Nitrox showed I could dive for a further 86 minutes before the dive became a decompression dive but the air computer showed only 39 minutes was allowed.

Three minutes later

Only three minutes later (and a little shallower), the Nitrox computer showed this would never be a decompression dive whilst the Air computer was offering 89 minutes before it became a decompression dive. Many of us older divers are also convinced that the more oxygen we can get, the better!

The disadvantage of Nitrox is that it reduces your maximum dive depth by an amount related to the strength of the mix. Hence we tend to do the first dive of the day (which is usually the deepest) on Air and subsequent dives on Nitrox.

Sha’ab Marsa Alam

Four hours sailing to the south of Port Ghalib is a coral reef which is in the bay off the actual city of Marsa Alam.

Sha'ab Marsa Alam

The dive plan is to go by rib round to the west of the Sha’ab, rib entry with negative buoyancy to 20m then fin / drift around the reef back to the boat.

We were told that there would not to be much to see other than the usual suspects. Whilst this was true, it was still a nice easy dive.

Accompanying us was a large Masked Puffer Fish

Masked Puffer fish

Numerous banner fish (which always go round in pairs)

Banner Fish

Coral and Antheas-1

and Antheas by the million surrounding coral outcrops. The Coral provided a home to many Sea Cucumber

Sea Cucumber and Fish

and the coral itself came in numerous shapes, sizes and colours.

Coral Crop Fire Coral Coral and Antheas  Coral and Antheas Close Up    Pink Coral   White Coral Large Coral covered with Anenome

Some way off the reef were a number of large coral blocks covered with anemones which

.Anenome Close Up

when seen closer up, showed their tendrils moving in the current.

As promised, it was reasonably interesting and a chance to get used to diving deeper again. After this dive, it was dinner and then an overnight sail for 12 hours down to St John’s.

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