How rare is extended range trimix?

[LiteHedded]

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.

a good hypoxic trimix class should be about more than dive planning. the added wrinkle of don't breathe this before it's breathable alone doesn't really necessitate a class
but there's a LOT more going on skills-wise on a 300' dive vs a 150' dive

 

[TONY CHANEY]

Great time for this thread in that I was just talking to my buddy and Instructor. I pretty much came to realize that at 51 I have more dives behind me than ahead of me. There is also all the other reasons stated by the other post. So I will not be taking the class.

 

[CAPTAIN SINBAD]

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.

 

[boulderjohn]

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.

The answer is------it depends.

The price for your own gases depends upon the location. Helium prices vary quite a bit, and you are using a lot of helium. (I am assuming open circuit in my calculations.) The next question is how long you are staying at 300 feet. At that depth, you go through that expensive gas in a hurry, and you really rack up the decompression time required for every minute you stay. Then you have to think about your support. When I did a 300+ foot dive in Cozumel a couple of years ago, I not only had to pay all the previously mentioned expenses, I had to deal with the fact that I had to pay a boat fee, a technical dive master (required by law), the technical divemaster's gases, etc. If it were just me by myself paying for all that, it would have been about $750-$800 for that day of diving. I managed to get in with a group and saved a few hundred.

 

[PfcAJ]

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.

Once you have all the gear its not bananas expensive, at least not around here in Florida. The gas is a minor cost compared to all the accoutrements you need (suit, light, tanks, regs, classes, etc).

The REAL cost is the experience needed to get there.

 

[Tug]

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.

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.


Sent from my iPhone using Tapatalk

 

[RJP]

If it were just me by myself paying for all that, it would have been about $750-$800 for that day of diving. I managed to get in with a group and saved a few hundred.

As my wife says "If you 'save' any more money on diving we're gonna need to sell the house."

 

[ajduplessis]

Houses are so overrated anyway, get something smaller. They also pay good money on the black market of organs.

 

[Germie]

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.

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.

 

[Subcooled]

I am not a commercial diver (and not a rebreather diver either), but I believe that the following is obvious:

Diving to 330ft to rescue a submarine means that one has to spend quite some time at depth - possibly doing heavy physical labor and not just float around. This would require a support vessel with hyperbaric living quarters, a diving bell with surface supplied mix, hardhat divers, and it would be a saturation dive, right?

Deep rebreather diving and physical excertion is a deadly combination. CO2 kills.