Drop bottle and planning.

J

jas kev

Member
Looking at building up depth and Times on unit this year and a drop bottle seems a sensible investment.
What's the consensus on planning? My current thoughts are plan on two ali 80s I carry for bailout and the drop bottle for if the shit hits the fan. I realise this doesn't necessarily extend gas available but would allow me to plan using the full contents of that carried with the security of knowing extra gas is available if required.
 
Drop bottles work best on decompresion stations. In this event i will consider it in my gas plan however Ill always have a back up plan bassed on carried gas

When I dive say 70m 3 hours I arry a 10ltr steel trimix deep bailout and a AL80 Nitrox 50%

Allowing for a drop tank of 80% ill plan normal deco bassed on elevated 25 SAC

In the event of a bailout i should have a ton of gas if I get the drop tank OK

However if I cant get the drop tank I have a back up deco plan bassed on my normal SAC and deep bailout + 50% only

Its often likley to bend me as its prety agresive but at least its a plan I can work to.

In order for this to work I need a decompresion computer like the Sheerwater which displays real time GFs and ill run all stops at 100GF and move up between stops maintaining 100GF. In this way i will save gas which can be used to extend my shalow time to the max

Ill adjust this on the fly if I feel I can extend my time with pure 02 CCR or SCR if necessary. I consider pure 02 CCR very viable but keep SCR as a very last resort.

When planning your drop tank make sure its a steel tank that way you can be confident it will sink quickly and when empty it wont be boyent and anoying

Drop tanks when drifting solo are another ball game which required a compitent skipper and proper planning. There are a few options but i most prefer the skiper lifting my SMB and cliping the tank to the line so it drops right on to my reel with 9m of roap and a float to suport it it wont screw with my boyancy.

Including the drop tank in planning with free drifting deco is something I would try and avoid but there are two skippers i trust to pull it off properly. My2p practtice it sand discover the issues it presents.

ATB
 
another option to consider, before taking the drop bottle route, is to add another 3l of O2 onto your box with an LP hose you can plug into the MAV and DV bungied to the side of the cylinder. That gives the option of O2 rebreather or 600l of OC oxygen for that last stop.
 
Cheers, Marks reply hits on my concerns of relying on a second party to drop the tank when needed. Will explore carrying an extra 3 (knew I should have kept that spare bracket) Will chat to regular skippers and assess their drop bottle thoughts.
 
Not in a dissimilar situation, I'm currently using 2 x 7. Thinking team bail out, although marks putting me off buddies ***55357;***56835; but also using my spare dil/O2 cylinders as additional bail out. Thinking I'd rather side mount, I've got one of AP's 3 ltr stage kits already which on its own works ok. Gonna have to play with carrying that as well as the 7's.
 
jas kev said:
Cheers, Marks reply hits on my concerns of relying on a second party to drop the tank when needed. Will explore carrying an extra 3 (knew I should have kept that spare bracket) Will chat to regular skippers and assess their drop bottle thoughts.
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It does work we tried it for real :D

Janos after a full flood of his KISS and full OC bailout with 9m drop tank on a 70m dive

new-4.gif
 
Jeff Pack said:
when we have a 3-4 hour dive plan, we carry 2 80s, and 2 40's each.
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I guess this is deep dive to have multiple gases but in cave country where the depths are around the 100-120 for most caves that I dive at this point it would make more sense to just carry two 85's at 3800psi.

How many gases do you carry for this dive Jeff?


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2 gases, 20/35 or 18/50, and 70%. If I don't have a 40 of 70%, then pure o2.

Its just volume of gas, not varied mixes.
 
There is no standard number of bottles for X run time

a 4 hour dive could be 20mins on the bottom at 100m and the rest deco or it could be a 2 hour bottom time and 2 hour deco

I once did a 3hour dive which was 1hour 20mins at 46m?

On such a dive i could get out on three tanks easy a 7 bottom mix and two 80s deco

However on the 4hour 100m dive its a diferent ball game Now i have a AL80 deep baiolout Steel 10 of 21/35 AL80 of 50% and a drop tank of 80% on the deco station

All good but what if its a shipwreck at 100m and theres a current and as a result i MUST get back to the shot or I will be drifting for three and a half hours and could end up 20 miles from the dive site.

Now my deep bailout needs to be enough to get me from the furthest point of the dive from the shot back to the shot. Then my intermediate gas needs to get me to the first deco gas. Then I need possably three deco mix?

On such a dive we would most likley stage 50% at 21m probably two 12ltr tanks

Then we would have drop tanks for the 6m stop

On a 100m dive the max i want to carry is two 80s and a single steel 10. The stress of kitting up with more tanks than this and the effort of diveing them on a wreck would outweigh the beniofit IMHO


You could of course run teem bailout but thats just like playing Russian Roulett in my book

ATB

Mark
 
Past my 4 tank config, is team bailout. Note, our dives are usually shore dives. If boat dives, I'd use drop tanks if feasible and go back to 2 tank config
 
Our dives here are open water, pretty shallow (max 60-70m), minimal deco (maybe 30-40min hanging). Usually two tanks of bailout and that's it.

On these dives we run a live boat and shot. Divers coming up deploy SMBs and leave the shot at 15m so everyone's floating kinda together at about the same time and they'll also be near(ish) the people who might not have made it back to the shot. The deal is: if you shoot a yellow bag with your name on it, and you have left a drop tank on the boat, it's coming to you. But maybe there are two groups and we can't get to you. Maybe your emergency bag's line comes up and snaps. Maybe you never bothered to check your drop tank's buoyancy and we can't get the bastard to sink. Maybe you got a knot in your line so the tank never gets to you. We've seen many of these things happen and I've kinda come to the conclusion: Take the gas you need with you on open water dives. No drop tanks, no staged tanks, carry what you need.

I'll admit: there are much better wrecks deeper in the graveyard, getting to the 100m mark. But I simply can't be arsed lugging an extra two tanks along for the dive. I've reached the point where I've decided the only way I'm heading that deep is with an s95 of deep bailout and a BOB with independent onboard O2.
 
Captain Starfish said:
Our dives here are open water, pretty shallow (max 60-70m), minimal deco (maybe 30-40min hanging). Usually two tanks of bailout and that's it.

On these dives we run a live boat and shot. Divers coming up deploy SMBs and leave the shot at 15m so everyone's floating kinda together at about the same time and they'll also be near(ish) the people who might not have made it back to the shot. The deal is: if you shoot a yellow bag with your name on it, and you have left a drop tank on the boat, it's coming to you. But maybe there are two groups and we can't get to you. Maybe your emergency bag's line comes up and snaps. Maybe you never bothered to check your drop tank's buoyancy and we can't get the bastard to sink. Maybe you got a knot in your line so the tank never gets to you. We've seen many of these things happen and I've kinda come to the conclusion: Take the gas you need with you on open water dives. No drop tanks, no staged tanks, carry what you need.

I'll admit: there are much better wrecks deeper in the graveyard, getting to the 100m mark. But I simply can't be arsed lugging an extra two tanks along for the dive. I've reached the point where I've decided the only way I'm heading that deep is with an s95 of deep bailout and a BOB with independent onboard O2.
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Re:bolded part. I've heard people say elsewhere that, despite not being a standard, if they see a yellow SMB they're going to give you gas based on some loose local tradition? I've never been on a dive where anybody has stated this beforehand (so I'm still a little unclear), and I'd be pretty pissed if someone started dropping tanks on me unannounced. Do you guys brief this pre-dive?
 
Yeah. We have a few requirements on our tech dives, an orange bag and a yellow bag are part of it. Our briefing in the week before pretty much says to shoot the orange if you're ok, yellow if something's gone runny. And tell the deck crew what you want us to do on a yellow bag. Sometime's it's motoring over and checking for a slate, sometimes it's dropping a bottle, sometimes it's getting a diver in the water to see what's going on.

Fortunately, so far, I'm the only one who's shot a yellow bag on these dives. And the skipper was smart enough to link it with the orange bag laying flat and drifting off and realise I'd shot yellow because my line had snapped on the orange. So she picked up the orange bag, came back and just watched. :)
 
JohnnyC said:
Re:bolded part. I've heard people say elsewhere that, despite not being a standard, if they see a yellow SMB they're going to give you gas based on some loose local tradition? I've never been on a dive where anybody has stated this beforehand (so I'm still a little unclear), and I'd be pretty pissed if someone started dropping tanks on me unannounced. Do you guys brief this pre-dive?
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So dont fire a yellow SMB simple???

I see a yellow your getting a drop tank no mater predive breif or not

You pissed off is of no consiquance to me

You dead is

ATB
 
Mark Chase said:
So dont fire a yellow SMB simple???

I see a yellow your getting a drop tank no mater predive breif or not

You pissed off is of no consiquance to me

You dead is

ATB
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Saw a yellow blob today as we pulled up to a site already being dived, made me twitchy seeing no one reacting to it. Worse still are the yellow and red ones wtf are they about.
 
Mark Chase said:
So dont fire a yellow SMB simple???

I see a yellow your getting a drop tank no mater predive breif or not

You pissed off is of no consiquance to me

You dead is

ATB
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Where is this a standard though? Like I said, I've never run into it. And this is the only place I've heard someone saying if they see a yellow SMB they're going to start pitching tanks overboard unannounced. Is this a UK thing we don't do over here in the States? Coincidentally I've noticed quite a few safety yellow SMB's as of late as more people learn that they are easier to see on the water.

As to the attitude concern, I can certainly see someone who was not expecting it, and not informed as to a non-universal procedure, returning the favor of the tank in a way which you may not appreciate.
 
Australia here.

The standard is Orange/Red DSMB = I'm here and I'm ok, Yellow DSMB = I'm here and I'm in trouble. Help.

Most likely source of trouble is an out of gas situation, so we send it. Worst case they just leave it on the shot.
 
Too many things to go wrong with drop tanks to build them into your standard bailout plan in my view. Could be used as a crisis management tool but if I need drop tanks as part of standard protocol I want them attached to an agreed process and a support diver.

As such I don't carry 2 SMBs. I have the gas I need, so does my team.

The thing i do think is nuts is not using a scooter as standard for deco dives with more than 2+ 80's. They are a massive safety feature when used in any area that has even mild current.


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JohnnyC said:
Where is this a standard though? Like I said, I've never run into it. And this is the only place I've heard someone saying if they see a yellow SMB they're going to start pitching tanks overboard unannounced. Is this a UK thing we don't do over here in the States? Coincidentally I've noticed quite a few safety yellow SMB's as of late as more people learn that they are easier to see on the water.

As to the attitude concern, I can certainly see someone who was not expecting it, and not informed as to a non-universal procedure, returning the favor of the tank in a way which you may not appreciate.
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Johnny, this is the way we teach it in our courses and also they way I have seen most teams do it here in the USA. That said, it is also standard procedure to review the color codes with the entire team as well as the boat crew prior to splashing. Obviously, it is critical that these types of discussions take place before each dive so that there is no misunderstandings whatsoever.

Warm regards,
Randy
 
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