Doubles for NC Wrecks

For those of you diving doubles on NC wrecks or other similar environments, what do you recommend doing? The environment I am thinking of is a dive boat, pretty far offshore, doing two dives. Generally, the first dive is deeper (100'-120') and the second a more shallow dive (50'-80'), but could be just two dives on the same site (i.e. both at 110'). These boats do not have compressors on board and are generally the domain of large single tank divers (Steel 95, 104, 120 or AL100) with pony bottles.

Since double AL80s are usually recommended, I was wondering how you get 2 dives off them? Do you just cut your second dive short so you come up with enough gas? If doing two deep dives, you would either have to cut both dives short or only do one dive since there wouldn't be enough gas in the Al80s to hit NDL twice on a 100'+ wreck with EANx30-32 and still leave a comfortable reserve. Do you carry a singles rig and dive it on your second dive? Do you carry stages?

I can't see any of the steel doubles sets working either since all the temperatures in NC are in the 70's-80's and definitely are in the wetsuit category. If steels were ok, then the problem would be easily solved by doubling up some 95s or 104s.

Thanks in advance for your assistance!

I don't know exactly which boat or boats you are talikng of, but I have been diving with Olympus since '89. There, when doubles are brought on board, maybe 50% of the divers or more, they typically bring singles or sometimes another set of doubles for their second dive too.

It sounds like you are only able to bring two tanks, is that the problem?

O-ring once bubbled...
I can't see any of the steel doubles sets working either since all the temperatures in NC are in the 70's-80's and definitely are in the wetsuit category. If steels were ok, then the problem would be easily solved by doubling up some 95s or 104s.

Thanks in advance for your assistance!

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The easiest thing to do would be to forget the "party line" for a day and dive double 104s

I know you won't since you're GUE certified but that's what I'd do.

Tom

It sounds like you are only able to bring two tanks, is that the problem?

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Just trying to figure out how you guys are doing it so one day when I do it I don't end up doing it wrong. You brought up one of the problems I was thinking about...two sets of doubles or a single. With another set of doubles (although expensive), problem solved...just switch over the tanks. With another single (attractive due to cost), I would have the problem of having to bring another regulator configured for singles (I ain't switching all those hoses every time I dive), another wing, and cam bands. This might not be a nightmare since I already have a singles wing and cam bands...I would just need another reg dedicated to singles use.

How are most people doing it?

The easiest thing to do would be to forget the "party line" for a day and dive double 104s

Click to expand...

Tom,
I dive single steels wet all the time, but I think the party line on that is a little gray....last I remember it was ok for single steels, but not doubles due to lack of redundant buoyancy control and the extreme negativity of diving double steels deep with wetsuit compression.

I shoulda' made a poll...

Please keep in mind that I do not dive NC wrecks. I would LOVE to, I just have not yet had the opprotunity. When I do get the chance, if I am going to be diving dry, then it is a moot point, and I will be diving a set of steel doubles. If I am going to be diving wet, a set of AL80's doubled up, and a stage bottle would suffice for two very nice dives IMO. This would be MUCH easier then switching out tanks. You could dive the stage on your first dive, and start your ascent at about 2500psi in your doubles. Assuming you have no deco obligation, or a very small deco, you could get back on board with over 2250 in your doubles, and that would make for a nice second dive in the shallower waters.


Of course, that was all just my opinion. Others could feel differently.

I do a good deal of diving in NC, most out of Hatteras (www.outerbanksdiving.com). I usually dive steel dbls. OMS 98's wet. For lift redundancy, I have a 90# lift bag, and sometimes a scooter. On other occasions, I use single OMS 131's (I take 2). And, on the rare occasion, I take the dbls. and a 131 to equalize the dbls. I know the lift bag is not really DIR... oh well.


Robert:doctor:

O-ring once bubbled...


Tom,
I dive single steels wet all the time, but I think the party line on that is a little gray....last I remember it was ok for single steels, but not doubles due to lack of redundant buoyancy control and the extreme negativity of diving double steels deep with wetsuit compression.

I shoulda' made a poll...

Click to expand...

You're right, it is a bit grey on singles. Personally I don't own a singles rig, I have 3 sets of doubles, 2 aluminum 80 sets, one steel 104 set. I dive them all wet, the only difference being that I carry a spare liftbag when I dive the steels.

Yea, double steels are damn heavy but I figure if worst comes to worst I can use my TIRD to get myself to the surface. It's really the one thing I don't agree with the party line on.

I own a drysuit but it's a compressed neoprene suit and the weather this time of the year is just too damn hot to wear it.

Tom

I tried to post this once before? I do a good deal of diving out of Hatteras (www.outerbanksdiving.com). I usually use dbl. OMS 98's and dive wet. For lift redundancy I use a 90# lift bag and sometimes a scooter. On some occasions, I dive single OMS 131's (I take 2). and on rare occasions, I take a set of dbls. and a 131 to equalize the dbls for the second dive. I know the lift bag is not DIR...oh well.


Robert
:doctor:

I dive a fair bit off the NC coast using double LP104s, and a double wing for backup buoyancy - I don't like a lift bag as backup since it's hard to control without clipping to it, and I never want to attach a lift bag to myself.

Not sure if captains will let you bring 3 full tanks on, but if so and you want to dive your doubles first and then a high capacity single, get an H valve for it - lets you run the same regs as on your doubles, and more importantly gives you reg failover if you're doing deco.