Adding Dil Injection button

wizbang

Hey Simon, I can see some logic in it but it seems awfull complicated, certainly more than I think it needs to be.

In your post #34 you said you wanted onboard to be air but even if it was normoxic, unless it was the same He content as the hypoxic you would need to stop for a decent few flushes to make sure you were breathing what you had planned on.

I don't see the point in using normoxic onboard to get to 40m considering you step off the boat with a PPO2 of 0.7 or more. The cost of hanging around at 40 on my way to 100 +, doing a good thorough flush just seems uneccesarily complicated.

I would hate to be in a current and needing to do my flushes.

Each to their own and I am sure you have it all sorted in your minds eye. I am sure the manual add button in the front with a gasket to strengthen it will be simple. Having an ADV in that position instead might give you some extra versatility.

Pictures of the procedure would be welcome.

Bubble Boy

Hi Wiz,

No it's simpler than it sounds!

And yes once I have made the mods required I'll send you some pictures.

silent running

Ummm, yeah. I found that aside from simplicity, another benefit of diving a single hypoxic mix was that it doesn't spike so easily on fast descents. I'm guessing that the O2 addition of any ECCR would be smoother with a hypoxic mix. Yet another reason not to switch Dils on deep dives...

Simon, I understand the idea of keeping things flexable by having another Dil add orafice, but you should remember that adding another button or ADV-which is what I would do and would also involve adding another strike plate on the back of the CL-is a good deal more complicated than getting an extra back gas cylinder and just switching them out for different profiles. As for the wisdom of always having a normoxic mix for OC BO, why not just make sure that you have at least 16/24 cyl for BO on 1 cyl? If its a really deep dive, you're going to have to carry 2 BO cyls anyway, why wouldn't 1 of them be normoxic? -Andy

Underwaterbear

Hey Simon,

Mike and I thought through this on the drive back from Bazzas a few weeks ago. I came up with the whip and prefferential IP idea (as it was what I was doing with my Azi) but ruled it out because of gas mixing and water ingress to first-stage issues. You could avoid this by making a manifold bar a-la inspo (but that seems a lot of hassle to me). MHO is that if you want to be able to switch dil underwater either do it at the ADV or add a button... As wiz points out you need to put a flow stop on the ADV if you do this...and this also makes your Air-2 redundant.

So I see your thinking, but I think you might like to step back and look again at how you think you'll be diving the rig. You say above you'll have air in the onboard (but you're not going to do air flushes are you?) and the advantage is therefor running tmx from your sling ..less fills etc. But that sling is part of your bailout strategy, right? If it is, this takes away a lot of your flexibility wrt gas choice and start pressures and you might be reconsidering the advantages of having access to the o/b gas through the adv and Air-2.

The bottom line for me is that lots of these mods are great for when the weather is fine, but when the show turns to custard have you compromised your options for getting out of dodge?

FWIW, I am diving single dil (10:50 deep, 15:30 or some other air top mix for shallower) and I carry appropriate bailout mix and volume for the deepest dive of the series. I have whips on the slings so I can plug them wherever I need to - usually suit inflation after the o/b (sure .7 will be enough!) cylinder runs out . But it can go onto the ADV if required.

On shallower stuff I choose from what's available and may only carry one bailout cyl if 2 are not required. For non tmx diving I have another 3L cyl that has air in him.

After thinking through the pro's and con's I decided that having plumbed in O/B gas is really only an advantage if you plan to dil flush (which I don't - until 6m) or if you think SCR is an important bailout mode for the particular dive.

Hope this all makes sense - still haven't had my coffee!

Bubble Boy

Hi Andy,

I'm not sure you follow why I'm looking at doing this. I want a normoxic mix for surface work before the dive. This is the most dangerous part of the dive and one where people don't give real credenance to the danger involved. For instance if you are breathing 10/50 on the surface then you may have as little as 3 to 4 breathes before unconciousness!

Also ifrun my main dil from the Offboard and onboard for suit and wing it makes gas management and repeat dives easier with no need to mess with the mix between dives.

As for the second striker plate - this would be unnecessary as I want the button to be a manual add instead of an ADV. So should be simple enough to put in.

Bubble Boy

[quote=Underwaterbear]Hey Simon,
... As wiz points out you need to put a flow stop on the ADV if you do this...and this also makes your Air-2 redundant.

??? Why so the flow stop is at the ADV not the feed. And yes it makes the ADV redundant for deep bail out but the slings have regs and who wants to breathe an Air 2 at 70 plus msw anyway

[quote=Underwaterbear]
So I see your thinking, but I think you might like to step back and look again at how you think you'll be diving the rig. You say above you'll have air in the onboard (but you're not going to do air flushes are you?) and the advantage is therefor running tmx from your sling ..less fills etc. But that sling is part of your bailout strategy, right? If it is, this takes away a lot of your flexibility wrt gas choice and start pressures and you might be reconsidering the advantages of having access to the o/b gas through the adv and Air-2.

The bottom line for me is that lots of these mods are great for when the weather is fine, but when the show turns to custard have you compromised your options for getting out of dodge?


Having dived this way on the Buddy and thought about how to dive the rig now I still feel this is less of a compromise and gives much more flexibility when looking at rig configuration. It's also something I'm used to so when the custard hits it's easy for me to deal with. Generally I find the off board for mix and on board for air fine as it's then the on board I use for wing and suit and have whips on both off boards as backups.

Possibly the biggest reason for doing this is the fact that the ADV doesn't swivel and points the wrong way for off board!

SO BACK ON THE THREAD TOPIC PEOPLE!!!!!!!
do any of you have experienbce adding a button,
or ideas on how to plumb an off board in with the ADV that doesn't look like some kind of bondage device with whips up behind my back?????..............

Bazza

Simon ..... you know you will have to visit the Troll Cave sooner or later. My magic bag of tricks will be laid out for you to fondle and drool over but remember there always a price to be paid for abandoning all hope and entering the enchanted cave.

Course I can do it .... regards Baz

Bubble Boy

Bazza,

I don't care what is in your "magic bag of tricks" - I'm not going to kiss you and certainly don't think you'll turn into a prince - cane toad maybe - but not a prince..........

BTW did your man drop off the light head yet?

Bazza

Sure did ... another reason to visit the Centre of Excellence.

regards Baz

silent running

[quote=Bubble Boy]Hi Andy,

I'm not sure you follow why I'm looking at doing this. I want a normoxic mix for surface work before the dive. This is the most dangerous part of the dive and one where people don't give real credenance to the danger involved. For instance if you are breathing 10/50 on the surface then you may have as little as 3 to 4 breathes before unconciousness![quote]




Hi Simon, forgive my lack, but what do you mean by surface work? prebreathe? Shallow bubble checks? Not sure. If you're using 10/50, aren't you doing a deep dive and thus need some normoxic BO anyway? And then it's still available from OC or whip.





[quote]Also irun my main dil from the Offboard and onboard for suit and wing it makes gas management and repeat dives easier with no need to mess with the mix between dives.[quote]





Yes, it makes sense. That's what my YBOD dive buddy in Indo did, who had 100 + 100 meter dives-what do I know?. But I still think simplicty trumps all in a crisis.









Yes, if you went that route, it would be simpler. I just think that if the ADV works well, why not replicate it? I think the shrader valve makes it easier to vary/control the volume of gas added-more dynamic. The button is more on/off. But I'm not worried, which ever way you go, you know what you're doing and have good reasons for your choices. -Andy