Galileo Sol, Independent Doubles and no-stop profile

Being an air hog sometimes I want to be able to dive independent double tanks in a no-stop dive to extend my bottom time. My computer is a Galileo Sol and both tanks have transmitters on them. The manual only talks about tank switching in deco diving modes and I will be diving no stop Nitrox. The mix in each tank could also be slightly different.

Is there a way in no-stop mode to tell it to switch tanks? I have not gone to the pool yet to try this but thought maybe someone may have had done this.

Although I admit I've not done so (not an air hog) I believe so. In fact, as I read the manual, I don't think that is what it says. It even says you can set both tanks to the same gas mixture although if they re different, they must be in ascending oxygen content. See section 3.7 page 61.

I had a chance to try this now. You have to turn on PMG (Predictive Multi Gas) feature, support more than one tank. Configure in a deco tank(TD) even though you do not have one. You can then configure in your second tank (T2) of your independent doubles setup as a second tank.

To switch tanks you just use the manual switching process for switching tanks switch under PMG, normally a deco process switch but we are diving no stop here. The transmitter from the second tank will have been shut down because you have not been breathing off it and will take a minute or so to fire up after you start breathing off the second tank. It will then take the computer a few more minutes to monitor your breathing to calculate a new no stop RBT for using the second tank. A few buttons to presses to get this all done buy easy after you practice a few times, pretty much that same thing you would do making a manual deco gas switch.

I used a quickdraw twins bracket to mount the twin tanks on my standard seaquest QD PRO BC, very slick. As this was this was independent doubles without a manifold. I just grabbed a couple tanks and in less the 30 second it was set up. As easy as mounting a single tank

Wouldn't it be easier to just get a bigger tank?

Or a manifold?

Sorry, but this phrase:

ssturges:

"The mix in each tank could also be slightly different."

Click to expand...

...suggests you could be using two different mixes for bottom mix - e.g. not planned deco mixes. Whats with the multiple mixes for bottom gas?

Sounds like a seriously funky configuration...lots of added complexity for no real benefit. You'll need to be real precise with your O2 analyzer, and plotting the multiple mixes into your computer. If one transmitter fails, you have issues. If you have EAN32 in one tank and EAN36 in the other, do you switch your max depths when you switch tanks? There are simpler ways of accomplishing the same thing, (like adding a manifold,) that might potentially be much safer for you, particularly as your multiple mixes become more diverse.

Another issue - do you brief your buddy on your rig each time, so your buddy is familiar with your rig?

Just some thoughts. Whatever pulls your trigger, but you can have the same amount of gas in a rig that allows you to have one bottom mix. Easier to plan your dive, and easier to dive multiple dives with it.

YMMV.

Doc

ssturges:

Being an air hog sometimes I want to be able to dive independent double tanks in a no-stop dive to extend my bottom time. My computer is a Galileo Sol and both tanks have transmitters on them. The manual only talks about tank switching in deco diving modes and I will be diving no stop Nitrox. The mix in each tank could also be slightly different.

Is there a way in no-stop mode to tell it to switch tanks? I have not gone to the pool yet to try this but thought maybe someone may have had done this.

Click to expand...

.................

I agree with Bill and respect his judgement and experience. Listen to what he says.

That said, if you travel single rental 80's may be the only option. In that case a set of travel bands and independent double may make sense for a diver with a high SAC rate (although you also need to assess why you have a high a SAC and work on resolving the problems that result in it being excessive - don't use more gas a crutch to avoid fixing the problem.)

If you are going to use independent doubles, manage them correctly. The only acceptable method that will keep you out of trouble is to:

1. Breathe 1/3rd of the first tank, then
2. Switch to the second tank and breathe 2/3rds of it, then
3. Switch back to the first tank and breathe the second 1/3rd of it.
4. Leave the last 1/3rd (1000 psi for an AL 80) in each tank as a reserve.

Number 4 seems overly conservative but 154 cu ft is a lot of gas even for a hoover and with that much gas you need an ample reserve for the depth, time and/or deco induced problems that could result.

Managing in that fashion will require an SPG on each tank. Using the elctronic transmitter on one of them is probably ok (I am not a fan of air integrated wireless computers on general principal as they are much more likely to fail at several points), but trying to use two transmitters and switch back and forth is overly complicated, complicates the two gas switches you need to make and is far harder than just using a normal SPG on the second tank clipped off on that side of your body.

And as Bill said, don't dive with two separate mixes - that is a fatality waiting to happen, especially when they are both back gas where you cannot directly verify and confirm the mix you are switching to.

It is possible to end up with a couple of rental tanks a percent or two off (both may nominally be 32% but one may be 31% and the other may be 33%) In that case program the computer with the lowest mix for the most conservative deco plan and then do the dive with the shallower MOD for the highest mix. If there is more than a couple of percent difference, reject one or both of the tanks when you analyze them at the rental counter or fill station and get two that are in the same ballpark.

Working on reducing the SAC or RMV rates would be one approach. In order to do that, we first look at trim and hydro-dynamics. Then we look at finning effectiveness. Consider having an instructor observe you and present some pointers. If you are cold, you may breath more quickly, so the exposure suit is also a place to look. Since you have a Galileo, what is your avg HR while diving? What is your health/fitness overall / out of the water?

If you're traveling and don't want to carry tanks, consider finding dive shops who do tech diving. Many of them will provide access to Steel 100's, sometimes 120's, and also doubles with manifolds. I don't have trouble with SAC, but I do prefer to use steel tanks for their negative buoyancy. I specifically look for Tech dive ops who rent them before I go on dive trips.

This was for travel where I would only have access to 80's. I normally dive a 120 locally with backup pony. My SAC is not all that bad .60 to .70 in or so but I hate being the one to call the dive. I did not find the complexity of switching that bad, just looks bad in words. I was just a few simple menu button press on the computer. If you have not see a Sol it as big advance over anyother computer as far as usability. I leave a reserve in both tanks. Just like have big pony.

In a question above, I can switch gas at any time as this is no stop diving and I am not using as deco stage. I would normally match the mix in both tanks to EAN32 or 36 or breath the lowest o2 mix first. My orignal question is how would the computer handle this. It worked fine the computer realized I was no stop diving and just recalcualted by bottom time when I switched tanks, pretty cool.