On my last dive to 400 Ft...

[MikeFerrara]

Swing weight could be same if you use the same amount of gas. Diving with a negatively buoyant tank allows you to wear less weight initially. You don't need to pump as much air into your BC at depth to compensate for the extra buoyancy of the AL 80. I find the extra 5 pounds and the added air to compensate for it annoying. I dive with a skin and 4 lbs of dumpable weight using a steel 100. It's perfect for me.

Assuming you are correctly weighted (neutral near the surface with a near empty tank) you'll have to pump exactly the same amount of air into the bc regardless of whether you use steel or aluminum.

When you add those extra pounds with an AL tank it's just to adjust your weighting as described above and you will NOT have to add extra to the BC.

A steel tank can be a big help in cold water where heavy exposure protection is required because it gets some of that weight off your hips. The goal being to have the center of gravity as close to the center of buoyancy as possible for the sake of trim...another concept that all too often, unfortunately, isn't introduced until cave or tech training.

I may be a stickler for details but these really are things you should understand before even thinking about venturing into overhead environments. Of course IMO they should be understood before getting einto the pool with scuba otherwise you just get messed up on everything else.

This conversation is giving me a nervous stomack. Please, for the sake of your life and my nerves get some instruction before going back into any caves. Reading about you proving me right by getting killed is not going to make me feel better. A good starting place is watching the video "A Deceptively Easy Way to Die". It was produced by DSAT and I think it's sold by both the NACD and the NSS-CDS. The practices in Cozumel were the original inspiration for that, BTW.

 

[JeffG]

There are so many cautions expressed and fears eluciated upon, I don't see how anyone does a dive at all without being paralyzed with fear.

So the better solution is "Ignorance is bliss"?

 

[MikeFerrara]

What you are saying is that diver should not dive Devil's Throat. You can't run a continuous line from the surface on a drift dive. The facts are, in case anyone is interested in facts rather than speculation, is that this dive hasn't proved fatal and is done safely every day. People have gotten bent at Punta Sur, but no has died in Devil's Throat as far as I know. It is not a dive for newbies, those inexperienced with depth, or fearful divers.

I'm saying that, I don't believe that a diver should do that dive without overhead environment training and NO diver with that training or experience needs a guide to check their gas.

I see tech divers attempting to impose tech procedures on rec divers and scaring newbies to the point they think they need ponies to dive Bonaire. I see it as the opposite extreme of incaution to the point of an OOA incident - the overplanning to the point of paranoia for very simple dives in many cases.

The "rules" I mentioned are for overhead environment diving whether you consider it or not. I, for one, am not trying to impose anything on you. I completely support your right to get dead in any way you choose. I just hate to see it happen because you were totally ignorant of how divers stay alive in overhead environments. It's not overplanning. the 5 guidlines I mentioned is the very minimum planning considered acceptable for diving in a an overhead environment.

There are so many cautions expressed and fears eluciated upon, I don't see how anyone does a dive at all without being paralyzed with fear.

I would only be afraid if I was doing them the way you apparantly are.

 

[TheRedHead]

This conversation is giving me a nervous stomack. Please, for the sake of your life and my nerves get some instruction before going back into any caves. Reading about you proving me right by getting killed is not going to make me feel better. A good starting place is watching the video "A Deceptively Easy Way to Die". It was produced by DSAT and I think it's sold by both the NACD and the NSS-CDS. The practices in Cozumel were the original inspiration for that, BTW.

Sorry, I didn't mean to give you a Malox moment here. I really have to disagree with you about diving in Cozumel unless you can provide some real statistics about real accidents involving dives people make on a regular basis. I've read Exley's books on cave diving and I dive with DMs who do have long hoses on their secondaries. I'm not uniformed; I have a difference of opinion.

I do plan to take Cavern and Intro in Mexico next spring. I like the buoyancy and reserve gas characteristics of steel tanks. I surface with a lot more gas and it makes me feel a lot better having extra gas for my buddy. Isn't that a good thing?

 

[MikeFerrara]

So you think it is NOT easier to manage gas with 120 cu ft. than 80 at 130 feet? However, people do manage this dive on an AL 80. I just prefer to bring more gas.

The gas volume doesn't have anything to do with making gas management easy or hard. You have enough for the planned dive or you don't.

In any overhead and certainly at your 140 ft I was some redundancy. If I was diving in a skin or a light wet suit my tanks of choice would be a set of AL doubles. A exceptable alternative would be a single tank of adequate volume with an H-valve.

Steel tanks can work as long as your rig is balanced right. Sometimes that doesn't work out though for divers not wearing buoyant exposure protection.

 

[TheRedHead]

I'm saying that, I don't believe that a diver should do that dive without overhead environment training and NO diver with that training or experience needs a guide to check their gas.

I didn't dive Devil's Throat with that operation so I can't comment on gas checking. Since there are many routes through the throat, if the group has enough gas (they descend and surface as a group), they can do alternative routes. They are certainly not checking to see if anyone is OOA. That's ridiculous.

The "rules" I mentioned are for overhead environment diving whether you consider it or not. I, for one, am not trying to impose anything on you. I completely support your right to get dead in any way you choose. I just hate to see it happen because you were totally ignorant of how divers stay alive in overhead environments. It's not overplanning. the 5 guidlines I mentioned is the very minimum planning considered acceptable for diving in a an overhead environment.

You can't run a guideline to the surface on a drift dive. I personally had 2 flashlights although I went through the throat without mine on as I could see perfectly well with all the illumination from the other lights. It's one way in and one way out. You can't get lost here. The real dangers, from having done the dive, are paranoid narcosis and getting stuck on the top from poor buoyancy control.

 

[TheRedHead]

Steel tanks can work as long as your rig is balanced right. Sometimes that doesn't work out though for divers not wearing buoyant exposure protection.

My cylinder of choice is the E7-100 and I don't have any problem with it.

 

[lamont]

Sorry, but when I read the description of the Devil's Throat dive, the picture I get in my mind is of an OW single tank diver taking a CO2 hit on the descent, going into a panic, trying to get out the way they got in and a snowballing cluster... Even if nothing quite that bad happens, taking too long to sort out a problem at 70-80 fsw and generating deco and air issues has to be fairly common, even with large steel tanks...

I'm sure its a wonderful dive if nothing goes wrong though...

 

[TheRedHead]

Sorry, but when I read the description of the Devil's Throat dive, the picture I get in my mind is of an OW single tank diver taking a CO2 hit on the descent, going into a panic, trying to get out the way they got in and a snowballing cluster... Even if nothing quite that bad happens, taking too long to sort out a problem at 70-80 fsw and generating deco and air issues has to be fairly common, even with large steel tanks...

I'm sure its a wonderful dive if nothing goes wrong though...

And you're absolutely right about that. I mentioned paranoid narcosis, but a CO2 hit would be just as bad. You can elect not to swim through and swim over. I would do that if I didn't feel right about the dive or even thumb the dive if I didn't feel good about it. You do have to use common sense in all diving, particularly deep dives.

The best way, IMO, is to make this a planned deco dive with plenty of gas. There's a lot of reef to explore at 25 feet when you off-gassing. Again, this is not for everyone.

 

[Soggy]

And you're absolutely right about that. I mentioned paranoid narcosis, but a CO2 hit would be just as bad. You can elect not to swim through and swim over. I would do that if I didn't feel right about the dive or even thumb the dive if I didn't feel good about it. You do have to use common sense in all diving, particularly deep dives.

And common sense dictates that if you are not trained for an overhead environment, you shouldn't really be there.