Going that little deeper

[michmoor]

Hello All,

I wonder if someone, probably you teccies can offer a bit of advice.

Myself and a couple of friends would like to go that little deeper than usually compressed air would allow, say up to 50m perhaps a little bit deeper. Recently I went to 41m on a U Boat, enjoyable but found myself feeling narked, in fact around the 35m to 40m mark I seem to be most susceptible to the onset of narcosis, so I wonder maybe if I want to do these dives, mixed gas is the solution.

I do not want to go down the full teccie route with several cylinders hanging round my body, but is there a course that would allow mixed gas use up to the round the 50m mark, without the need for multiple cylinders and regs. If so can someone point me in the direction of one?

Thanks in advance

Michael Moore

[PeteM]

Hello All,

I wonder if someone, probably you teccies can offer a bit of advice.

Myself and a couple of friends would like to go that little deeper than usually compressed air would allow, say up to 50m perhaps a little bit deeper. Recently I went to 41m on a U Boat, enjoyable but found myself feeling narked, in fact around the 35m to 40m mark I seem to be most susceptible to the onset of narcosis, so I wonder maybe if I want to do these dives, mixed gas is the solution.

I do not want to go down the full teccie route with several cylinders hanging round my body, but is there a course that would allow mixed gas use up to the round the 50m mark, without the need for multiple cylinders and regs. If so can someone point me in the direction of one?

Thanks in advance

Michael Moore

The problem is Helium is a very fast gas so it goes into the body quickly. This means if you do the whole dive on trimix when you do your first stop whilst helium will be coming out of fast tissues it will still be going into slow tissues, meaning the next stop will have to be longer, the next even longer. So you end up carrying silly amounts of gas to do silly amounts of stops.

To stop this happening you switch to a mix with no helium, i.e. nitrox.

Realistically you need a minimum of three cylinders for a mix dive, any of the normoxic courses will teach you how to use these

[Nigel Hewitt]

I do not want to go down the full teccie route with several cylinders hanging round my body, but is there a course that would allow mixed gas use up to the round the 50m mark, without the need for multiple cylinders and regs. If so can someone point me in the direction of one?Well this is normoxic. 60meters for most agencies.

The problem is that once you do a 50m wreck with a trimix clear head you discover the 8 minute no-stop time will annoy you no end so you'll end up wanting to do deco and suddenly accelerated deco with say, one rich nitrox, seems suddenly very attrractive.

Anyhow in the water those multiple cyclinders are trivial. Do a normoxic course so you have a deco ticket and dive stages when the target justifies doing the time hanging on a string. With the CCR I don't need the stages for a 60m dive, they are just there in case something breaks. They really aren't a problem.

[Chris Cherrington]

There is a course - IANTD Advanced Rec Trimix that caters for this sort of diving, but I'm afraid it is the general view of most agencies that beyond 35m or so you require twins and the IANTD course also uses accellerated decompression and therefore additional cylinders.

As Nigel says you will soon tire of doing 12 minute dives and you need at least twin tens to get a sensible 20-25 min BT at this depth. You do then also need a deco gas. However a single 7L is adequate for that depth for decompression.

I'm sure some will disagree, but recreational diving stops at 35-40m and IMO air stops at 35m. Therefore from SD onwards you need to look at the technical agencies, or the new BSAC mixed gas course if depth is the objective.

Chris

[Nick Kay]

I do not want to go down the full teccie route with several cylinders hanging round my body, but is there a course that would allow mixed gas use up to the round the 50m mark, without the need for multiple cylinders and regs. If so can someone point me in the direction of one?

If you're BSAC then the new Sports Mixed Gases course is coming in next year - aimed at exactly at divers like you (and me) who don't necessarily want to dive deep but take the edge off the narcosis by using Tx to 50m with a single stage cylinder...

[michmoor]

Thanks for the above everyone, if anyone else has got any more comments they would be welcome.

Thie new sports mixed gases course sounds interesting Nick, can anyone provide a bit more info on it?

Thanks in advance.

Michael Moore

[PeteM]

Thanks for the above everyone, if anyone else has got any more comments they would be welcome.

Thie new sports mixed gases course sounds interesting Nick, can anyone provide a bit more info on it?

Thanks in advance.

Michael Moore

Don't know anything about the BSAC course but IANTD do something similar, do a search in google for "Advanced Recreational Trimix Diver"

[Chris Cherrington]

If you're BSAC then the new Sports Mixed Gases course is coming in next year - aimed at exactly at divers like you (and me) who don't necessarily want to dive deep but take the edge off the narcosis by using Tx to 50m with a single stage cylinder...

I don't think so. 50m is too deep for a single tank (unless its a 18L) and I don't think you will find the BSAC mixed gas course caters for it. The course is for Tx to 80m

Chris

[Nick Jones]

I don't think so. 50m is too deep for a single tank (unless its a 18L) and I don't think you will find the BSAC mixed gas course caters for it. The course is for Tx to 80m

Chris


Chirs,

You've misread that reply from Nick,

The Sports Mixed Gas is for Normoxic Tx to 50m using Twins and a single stage cylinder. Advanced Mixed Gas is for Hypoxic and 2 stages to a maximum of 80m.

Cheers

Nick

[Chris Cherrington]

Chirs,

You've misread that reply from Nick,

The Sports Mixed Gas is for Normoxic Tx to 50m using Twins and a single stage cylinder. Advanced Mixed Gas is for Hypoxic and 2 stages to a maximum of 80m.

Cheers

Nick

Yup sorry - single stage tank... (Friday :))

Still not what the OP wanted I think.

Chris

[Steve Pearson]

Chirs,

You've misread that reply from Nick,

The Sports Mixed Gas is for Normoxic Tx to 50m using Twins and a single stage cylinder. Advanced Mixed Gas is for Hypoxic and 2 stages to a maximum of 80m.

Cheers

Nick

Hi Nick

Hope you're keeping well.

I'm organising a deep tx dive about 75-80m on an undived wreck off the coast of North Wales, next year if you're interested. It'll be a team dive with support divers etc to survey the wreck and provide information about it.

PM me if you fancy coming.

Steve

[Nick Kay]

Hi Steve

1. Trying to get my ERD Instructor ticket at present - every time I get sorted either the date changes or I become unavailable - now trying for 1st w/end in October

2. Not sure about next year...
- Never did the hypoxic Tx so only rated to 60m on normoxic; and

3. Hoping to go xCR in 2 months time so:
- will be teaching (ITS) on single
- will be teaching CNx/ERD (hopefully) on twins
- will be trying to rack up my hours on SCR before
- converting to mCCR before
- doing mCCR/TX

And, ticked a lot of boxes on the ITS schedule for next year!

On top of that, will try & get in some "proper" diving

[depth-junkie]

Hi Steve

Myself and my mate Steve Geraghty will be up for the North Wales Dive. Let me know what dates you are looking at, and i will pencil it in the diary for next year.

Are you running this over a weekend or just one day ?

ATB
Gareth