Can open circuit technical divers go down to 400+ feet or is a CCR Rebreather required?

[Khalil Rodriguez]

Can open circuit technical divers go down to 400+ feet or is a CCR Rebreather required?

 

[PfcAJ]

Britannic 99 | Global Underwater Explorers

 

[WarrenZ]

I'm gonna say yes BUT the required gas will make the dive cost prohibitive.

 

[nadwidny]

OC can but obviously not the best choice. I remember my friend Bob Foster talking about his dives on the Palmer and Crary (~350' I think). He said he used a T's worth of helium. Something 400'+ will use a lot more.

 

[hroark2112]

You can do a 1200' dive on OC. Coming back up....not so much.

 

[ajduplessis]

@KR: Yes we do 400 with OC on a regular basis as part of our research efforts.

Interesting though is many divers in our group have tx ccr certs, but when we do the big dives the yellow boxes stay topside.

 

[ajduplessis]

I'm gonna say yes BUT the required gas will make the dive cost prohibitive.

And buying a CCR, getting the training plus the rest of the expenses is less cost prohibitive?

 

[WarrenZ]

How much does helium cost? OC each breath that helium is gone a rebreather allows the gas to be reused and giving you runtime out of it.

Of course the number of bailout tanks will be impressive for a 400 foot dive also.

 

[ajduplessis]

You blend two 400ft dives out of a tube of helium. Go make the sums to buy, dive and maintain a CCR over time (will leave training out of this) and see where you break even compared to buying He of OC.

You need to make your own sums based on how you dive to really know if CCR is going to be cheaper over a period of time. If your intent is to not exceed a life time 20-70 300ft-400ft, or very long (3hours + deco) rather dives stay on OC.

Either way, trimix diving is an expensive hobby.

 

[WarrenZ]

True I suppose if you are making just a few dives then maybe the cost of the rebreather wont work out but if you are making a habit of 3-400 foot dives then gas costs add up quickly.