No Deco limits on deep (~100') double dips

[Shabaday]

Why not tell the OP what he needs to know:
first get certified for nitrox
second use nitrox and
third those dives are definitely worth doing .
Forth, use a computer and you will get credit for a bunch of time spent high up on the ship, so chances are he will be limited by tank size rather than no deco limits.

He says he will be diving Nitrox....anywhere from 29-32%
I can tell you when I do this with a 100 tank I typically do a stop at 20 feet for at least five minutes....sometimes longer around 10 minutes.....manage your gas supply and you will be fine. If you are in a high current holding on to the line can get exhausting so make sure you have a Jon line dive-rite-jon-line-w-carabiner

 

[Wibble]

Rule of thumb:

• 30m/100ft gives you 20mins on air and 30mins on 32% nitrox.
• Every 3m/10ft shallower gives you 5mins on air and 10mins on 32%

With a dive to 27m/90ft you get 25mins on air or 40mins on Nitrox. Coming up shallower means you start to decompress a bit, so you can go down for another go.

Use MultiDeco to work out your dive plan.

But just use a computer. It's so much easier.

 

[Degenerate]

Rule of thumb:

• 30m/100ft gives you 20mins on air and 30mins on 32% nitrox.
• Every 3m/10ft shallower gives you 5mins on air and 10mins on 32%

With a dive to 27m/90ft you get 25mins on air or 40mins on Nitrox. Coming up shallower means you start to decompress a bit, so you can go down for another go.

Use MultiDeco to work out your dive plan.

But just use a computer. It's so much easier.

What gradient factors are you using to get those times/depths with air...?
Even running 95/100 I am still getting a short deco stop at 6m for 20 mins at 30m.

 

[Celt]

110ft for 25min on nitrox 32, 60min surface interval, 80ft for 25min on nitrox 32

 

[Centrals]

Yes, as I stated above, I dive nitrox, use a computer and have been on these wrecks before. I guess I could try to do dive planning, but I'm not sure I'd know what actual depths I'd be at and for how long, so was more curious if people had rule-of-thumb experience about them being a good or bad idea. One of the most popular dive shops doesn't do double dips very often, so was curious if that was for NoDeco reasons.

You have been on those wrecks before! But you have no record or recollection on those dives.
Now you know the advantage of having a log book in what ever format.

 

[tursiops]

Hi - I'm planning a two-day trip down to FL and trying to decide whether a double dip to one of their deeper wrecks makes sense. The two I'm considering are mostly 70-90' or 80'-110', I think (Spiegel and Duane). With a standard 60 minute dive interval, does a second dive to these depths become so short it's not worth it? I got my OW back in the days before computers, and could probably do the trip plan, but I know the charts are overly conservative compared to a computer that is actually tracking your dive, so I'm curious what a real-life dive would result in, in terms of the 2nd dive bottom time. Thanks!

On Nitrox you'll be fine; on air you'll be unhappy.

 

[PfcAJ]

What gradient factors are you using to get those times/depths with air...?
Even running 95/100 I am still getting a short deco stop at 6m for 20 mins at 30m.

NAUI dive table shows 100ft for 20min as the upper limit of no deco.

 

[rob.mwpropane]

NAUI dive table shows 100ft for 20min as the upper limit of no deco.

For 32%?

 

[rhwestfall]

Air

 

[kelemvor]

Is the "60-minute standard surface interval" a valid assumption for operators on these sites?

For most "large" operations in FL, that's the standard enforced SIT. Smaller operations and tech trips with the large ops will generally let you plan your own dives once they have a warm fuzzy you are competent.

Best bet is to call the operator you're planning to dive with. That's always a good way to avoid unpleasant surprises.