Double 80s

[teknitroxdiver]

I emailed IANTD to see if it's possible to have Decompression Procedures (think thats what they call it) done with Adv. Nitrox if you're under 18. If I can, then I will be doing decompression diving, if not, well, forget the doubles for now.

 

[ianr33]

I find doubles to be very useful if you want to do ,say ,100 feet for 30 minutes on Nitrox 32. Dont think you would have much gas left after that with a single 80.

TDI advanced nitrox allows for minimal deco,I would imagine IANTD is similar

 

[teknitroxdiver]

True, or 35 on 36%.

Yes, IANTD allows for minimal deco, but I don't know if they will if the student is under 18.

thanks

 

[Don Burke]

To make a controlled accent and not have to shoot to the surface like a rocket. If your doing a 150Ft dive the wet suit loses allot of it bouyancy and if you dump your weights and you have al tanks there will be no chance for deco, Increased risk for DCS or serious injury. Now if your not going to do deep dives then maybe it might not make much differance. Although he never said how deep he was planning on diving. Either way I perfer a controlled accent over dumping weights and a chance of injury.

The idea with aluminum tanks and a wetsuit is that by the time you have a signifigant decompression obligation you will have used up enough of your backgas that you can just swim the rest up.

Ditching weight is something normally done at the surface, although if the weight ditched is small enough, the ascent is easily controlled if you ditch at depth. At one point I thought having enough ditchable weight to offset the wetsuit was a good idea. Now I just wear enough to account for backgas.

Someone who wears thirty pounds on a belt does not have ditching at depth as an option, so he might as well weld the buckle shut. Many divers dive this way and on a catastrophic BC failure early in the dive, they could be screwed. I hope you are not one of those people.

Nearly half of your wetsuit buoyancy is gone at 33 feet. From 50 feet down the change is so slight you may not notice it for a depth excursion of 30 feet or so.

 

[teknitroxdiver]

I only take enough weight so that I am neutral at the end of the dive. And, like you said, on a deco dive dumping large amounts of weight in an emergency is the last thing you want to do!

Thanks everyone for the input

 

[Curt Bowen]

Someone who wears thirty pounds on a belt does not have ditching at depth as an option, so he might as well weld the buckle shut. Many divers dive this way and on a catastrophic BC failure early in the dive, they could be screwed. I hope you are not one of those people.

With most doubles diving, no weight belt is needed due to the increased weight of the cylinders and stainless back plate, thus there is no weight you could ever drop, except the doubles on your back.

If you should need to add weight, I would suggest a tank weight for the middle of the cylinders or if your having problems with proper swimming possition, (head down feet up) either shoulder weights if your feet are to heavy or anckle weights if your head is to heavy. Before adding the weights try to lower or raise the tank bands on the doubles. This will change your swimming possition without needing to ad weights.

If your concerned about having a bcd failure, buy a double bladder set of wings, or double up on wings.

A failure in a BCD is possible and has actualy happened to me once, but I was wearing my dry suit at the time.

 

[Don Burke]

If your concerned about having a bcd failure, buy a double bladder set of wings, or double up on wings.

A small amount of ditchable weight covers it for me.

 

[Don Burke]

I only take enough weight so that I am neutral at the end of the dive. And, like you said, on a deco dive dumping large amounts of weight in an emergency is the last thing you want to do!

Thanks everyone for the input

Weighting to be neutral is only part of the weighting issue.

The possibility of a BC failure needs to be addressed. When I am in a wetsuit, some of my weight is ditchable. In a drysuit, the drysuit is my backup to the BC.

Some go with the double bladder or wear two wings. I have not found that necessary.