How rare is extended range trimix?

[kensuf]

Useful information guys. Can anyone give a rough idea of the cost of a 300 ft dive? By cost I mean cost / diver in terms of breathing gasses, equipment, boat charter and insurance? If someone has trained for that depth then I am sure they would want to do at least 1 dive a year in that capacity otherwise it is really not worth it.

My dive at Diepolder 3 two weekends ago was about $135. Granted, that was 270' and not 300', but close enough. $110 was bottom mix and deco gases. $25 was the daily entry fee.

Dive was 30 minutes at depth (average depth 220'). I used roughly 80 cubic feet of bottom mix (14/55), 20 cubic feet of travel gas (30/35), 20 cubic feet of 50%, and 20 cubic feet of O2.

 

[Tracy]

With helium prices locally, a set of double 130's filled would cost about $250 in gas alone. Although this filling from empty, a lot of places can top off what you already have in the tanks, so the realistic cost would be cheaper. Probably figure another $75-100 in deco gasses.

As far as equipment goes, nothing that you wouldn't already have is really needed.

Charter costs would probably set you back another $100-150 for a space on a boat and tips. This is all figuring that there are enough people to split the boat fee.


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I am glad I don't dive where you are. I pay about 50 cents per cubic foot here.

 

[Omisson]

Most people I know stop before that (training, that is), because if you can pan a 150ft trimix dive you can plan a 300ft trimix dive.

That's a pretty dangerous proposition.

Normoxic and Hypoxic Trimix are very different creatures. Anyone who does Normoxic Trimix training and thinks it's good enough for Hypoxic mixes is taking a real risk.

 

[LiteHedded]

First, a oc full trimix course will let you dive with hypoxic gases. Already in a normoxic course you can dive with 2 stages, but then all the gases are breathable at surface. Most times you dive then with 1 bottomgas in twinset and 2 decogases in a normoxic class. Yes, a 75m dive can be done in the same way. Just go down on a 50% decogas, switch at 21m to backgas and dive. Way up use the 50% and the 100%. But if this is your full trimix class, then take another instructor.
Some instructors let you dive a hypoxic course with just 2 stages, but I prefer to find an instructor that let you dive with 3 stages (a real travelgas and 2 decogases), using a leash and learn some cylinder rotation.

300ft/100m is quite a lot deeper. For a bounce, divetime can be less than 1 hour. But I don’t think you mean this.


In warm water, good visability and no current, I can do 15-20 minutes on a twin12, but my sac is less than average. Let’s talk about a 15 minutes bottomtime in a twin12. The problem is most times not your bottomgas, but in the decogases. For such a dive you need a travelgas.

The max PO2 of bottomgas is most times 1.4 max, and for deco 1.6. I know the discussion of lowering the PO2 of bottomgas, but on dives at 100m depth, the difference between 1.4 and 1.2 can be minutes of deco. You have to think about safety on PO2 and what can I do with the decogases? If you want to dive DIR, then the bottomgas will be 10/70. If you want to dive a best mix, then it can be different.
Let’s say you want to use a 12% oxygen as bottomgas, PO2 is then 1.3. The amount of helium? That depends on your END. You like around 30m? ok, more helium than END around 40m. The price difference in a 12/60 fill and a 10/70 depends on the costs of helium, but is around 10-15 euro here. A 10/70 costs here between 70-120 euro. Depending on where you fill.
Some divers prefer only 50% helium, but I have dived to 103m oc on a 13/55 gas and was not happy on the way down. Fast down means more sensitive for being narked and I was really narked when I was at 103m (delta P). So I prefer to have at least 60% helium at 100m

Then the travelgas. Let’s say to get down to a 30m and on the way up from around 80m-60m (sorry, I am used to use meters). Then you have something with a 18%-20% oxygen as travelgas. The amount of helium depends on the bottomgas too.
DIR means 10/70 as bottomgas, then an 15/55 and/or 18/45 as travelgas, then a 50/25 as decogas and a 100%.
You want to avoid icd. The more helium in the bottomgas, the more helium in travelgas and first decogas needed. So the travel gas has between 35% and 50% helium most times. On such dives the problem is not the bottomgas, but the travelgas in reserves. Costs 20-30 euro.

Then the first decogas. There is still some helium in it needed, 15-25% most times. The oxygen content depends on where you want to switch. 40% on 30m, 50% on 21m. If you calculate that you will run low on the travelgas, then you choose a 40% oxygen with some helium. If you can go to 21m, then you can decide to take a 50% with some helium. Costs around 15-20 euro

The last decogas will be 80-100%. Most times such a gas costs around 20 euro.
You see, different gases means different costs.

The other costs of such a dive:
-divecenter and boat, I paid in Malta for a 110m (wreck 100-120m) dive 65 euro for the boat. In Gozo you can reach 110m from shore (not most interesting). Another deep wreck was for a 2.5 hour runtime 90 euro (France). Some divecenters calculate the costs depending on the runtime.
-important: safetydivers or not and what do they cost?
-hire of cylinders

So such a dive can cost 200-250 euro. Let’s find a nice wreck to make such a dive the money worth.
Another 100m dive costs depends if topups are possible or that you have to pay again for full cylinders. My twinset has 100-110 bars left on such dives.

CCR:
Helium and oxygen costs less than 30 euro. Sofnolime 10-15 euro (some divecenters ask 25 euro for a fill).
You need bailoutcylinders. If you use your own, then no other costs. I know divecenters they sell you the gases in the cylinders and calculate hire and after a week they sell again the gases to another diver.
If you have to use the bailouts, then you need to pay for new fills. If you don’t use bailout, then you can use it again.
Boatcosts are same.
If you organise yourself, then the costs are fuel and fills for diluent and oxygen and sofnolime. 2 dives to 130m did cost me 2 weeks ago 300 euro, so 150 euro each. That was including fuel and hotel and food. We dived in a mountainlake in Swiss, and did not use a divecenter.

what you've said about 'dir' gases is incorrect. unless UTD is doing something weird, which is entirely possible

 

[Omisson]

If it had gone down off the New Jersey coast, it wouldn't have been that deep in the first place. We have a shallow shelf here. You have to go out a helluva long way to find that depth.

The Doria which is one of the deep wrecks is a real haul from shore - overnight bag required. It's "only" 190-240 feet....

 

[PfcAJ]

Wtf would you use 15/55 as a travel gas? The entire point is to have something normoxic at the surface...

 

[MXGratefulDiver]

If it had gone down off the New Jersey coast, it wouldn't have been that deep in the first place. We have a shallow shelf here. You have to go out a helluva long way to find that depth.

There's places in Puget Sound you can hit 330 feet on a shore dive. The Admiral Sampson sits at 320, and I know several divers who've dived it ...

... Bob (Grateful Diver)

 

[Omisson]

There's places in Puget Sound you can hit 330 feet on a shore dive. The Admiral Sampson sits at 320, and I know several divers who've dived it ...

... Bob (Grateful Diver)

The Atlantic shelf has a few spots all over that run that depth range. The Pacific is somewhat more variable because it's a "newer" coast.

How cold is the 320' range in the sound?

 

[Tug]

I am glad I don't dive where you are. I pay about 50 cents per cubic foot here.

oh the things I would do to pay $0.50 a cubic foot...

I think it's around $1.25 here depending on the shop. Another reason I just purchased a rebreather


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[Wookie]

oh the things I would do to pay $0.50 a cubic foot...

I think it's around $1.25 here depending on the shop. Another reason I just purchased a rebreather


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I thought you purchased a rebreather because you were too busy working to actually go diving.