Safety Divers for Deep Dives - What Do They Do?

[fweber]

Lets say your team is doing a 250 dive with the first switch at 120. Would you want 15/55 in your back gas? I would say 25/25. You get a benifit of the higher 02 and helium. Less potential to go into deco at that depth. If you have the vis to see your team at depth(which we dont have anything of the sort here in the northwest) asending on a gas share I would assume that the team has calculated a rock bottom and has the gas to make it to the first switch. It may be inconviente for them but if the skill was not there to do a gas share and hold relatively short deep stops then some practice is in store for the team. I would not leave the team untill each member has at least one redundant gas supply. IE the OOA diver Has his 120 bottle and their 70 bottle @ 70 ft to use.

The most imporatant thing here is that the team is on the same page at all times. I only dive with the same 5 people. We are all trimix 2 cert. We take turns safety diving for eachother. Comunication is easy underwater for us. If we charter a boat it is with someone we trust and just happens to also be a trimix diver. Reducing the risk as a whole equals safe diving for all.

I think the role of safety diver vs support diver can be very blurry. Per the earlier definitions, we're certainly blurring that line here.

I think we largely agree and that perhaps our differences are based on our particular logistical needs.

A drop line can be extremely valuable for things like depositing an o2 cylinder or as a clip off point during the exchange of equipment. I've now fabricated a trapeze for this. You don't have to hang on it. It just makes an extremely comfortable and stable platform to work off of. The next step will be to plumb it to onboard O2.

With regard to what the safety diver is carrying on their back and what they may be breathing is the thing we differ on and I suspect that is because of conditions. 100' vis isn't unussual for us and <30' would be a very bad day. With that in mind it is very likely that the safety diver would be able to see the bottom team from whereever they might be stationed. It would seem incomprehensible for us to watch our friends and buddies struggling with an emergency and, do to mix, be unable to go help them. But, that's just our take on it.

Massive agreement about the importance of the team staying on the same page and the ability to easily communicate. We just added a third this year and hence our ability to alternate one as a safety. The more you dive with the same cohesive team, the easier it gets to get things done and know what you're teammates are thinking.

 

[texdiveguy]

He must mean 25/25 in your deco bottle. 25/25 at 250' is a po2 of 2.12 and an end of 177'.


Or something...

....yea I figured a 'typo'....but you never know with folks on these boards.

 

[JeffG]

First, you're assuming that the first gas switch won't be happening any deeper than 70'. I understand that would be the standard GUE gas to combine with oxygen. However, a team may be making their first switch at a depth greater than 70'. Either due to the use of a third gas, or because they've chosen a gas other than 50%.

You shouldn't have to meet the divers deeper than 70ft.

If the divers have a 120ft stop, that bottle should already be clipped to the right spot. They have a team mate. They should be fine to do it themselves.

At 70 ft though. Life can get interesting depending on the dive plan.

A bottom diver could be configured with
a) Back Gas
b) Back gas stage (clipped to shoulder)
c) 40 ft3 - 120ft bottle (clipped to shoulder)
d) 40 of 50% and a 40 of 100% clipped to a leash (which is clipped to the rear D-Ring)

(Typical setup of the 300ft bottom divers doing the Athel Viking in Halifax)


At the 70 ft stop, the bottom diver has to move the 50% and 100% to his shoulder...which means he first has to get rid of the stage and the 120 bottle. (Which at this state have been used and are positive. The 50% and 100% are negative)

If there is going to be an accident...this is where it is going to happen.

The 120 stop is easy peasy. No need for a support diver to be there.


On another note: I always used my scooter while doing support dives. Allowed me to go from team to team in a hurry.

Plus some of us had a blast racing around in circles during the 20ft stop

 

[texdiveguy]

c) 40 ft3 - 120ft bottle (clipped to shoulder)
d) 40 of 50% and a 40 of 100% clipped to a leash (which is clipped to the rear D-Ring)

40's....heck those are just for 'wimps'....get some real cylinders like 80's or 50's or a good ole steel 72......ha 40's !! :mooner:

 

[fweber]

You shouldn't have to meet the divers deeper than 70ft.

The 120 stop is easy peasy. No need for a support diver to be there.

"Yeah, well, you know, that's just, like, your opinion, man. "

 

[JeffG]

40's....heck those are just for 'wimps'....get some real cylinders like 80's or 50's or a good ole steel 72......ha 40's !! :mooner:

If you need an 80 deco bottle, you shouldn't be doing dives like that.

and I won't even mention the use of steel deco bottles.

 

[JeffG]

"Yeah, well, you know, that's just, like, your opinion, man. "

Whatever.

 

[texdiveguy]

If you need an 80 deco bottle, you shouldn't be doing dives like that.

and I won't even mention the use of steel deco bottles.

....... ..... I forgot you are the 'expert'.....get real.

 

[JeffG]

....... ..... I forgot you are the 'expert'.....get real.

That right. Attack the person because you can't argue the facts.

Too rich.

Do you dive?

 

[texdiveguy]

That right. Attack the person because you can't argue the facts.

Too rich.

Do you dive?

No I never dive.....why should we....we have SB .....cheaper.

I persl. find 80's a great bottle for staged deco dives......I was not aware divers did not use them....and that the 40's was the only way to go.....dang must be a ton of deep divers in error. I even use 50's..... and steel on occasions when conditions warrant. I and a lot of divers must have missed the 40cf only rule for deco.
Use whats best for you based on your needs.