Question Do you ever practice dropping weights and handling the unexpected ascent?

[Nick_Radov]

Why is this? Where does this rule of thumb come from? Why is it safe for a diver with two tanks to have double the ditchable weight that a single tank diver does? I am really curious, how this guideline has been developed and exactly what logic is a being applied, when we are talking about a recreational diver?

Some divers do recreational dives with double tanks. If you have a total BC failure at the start of a dive with full tanks then you should be able to ditch enough weight to get neutral on the surface. This doesn't necessarily mean carrying extra weight with doubles, but relative to using a single tank it usually means shifting more of your total weight to be ditchable versus non-ditchable. And it becomes even more critical to have reliable gear to avoid accidentally dropping weights.

Anyway I don't want to take this discussion totally off topic for the Basic Scuba forum. Suffice it to say that assembling a balanced rig becomes more complex with multiple tanks and if you want to get into the details it would be better to ask on a different forum. Search the archives for "balanced rig" and you'll find a lot of prior discussions that should get you clear on the basics.

 

[johndiver999]

Some divers do recreational dives with double tanks. If you have a total BC failure at the start of a dive with full tanks then you should be able to ditch enough weight to get neutral on the surface. This doesn't necessarily mean carrying extra weight with doubles, but relative to using a single tank it usually means shifting more of your total weight to be ditchable versus non-ditchable. And it becomes even more critical to have reliable gear to avoid accidentally dropping weights.

Anyway I don't want to take this discussion totally off topic for the Basic Scuba forum. Suffice it to say that assembling a balanced rig becomes more complex with multiple tanks and if you want to get into the details it would be better to ask on a different forum. Search the archives for "balanced rig" and you'll find a lot of prior discussions that should get you clear on the basics.

thanks, so the issue is establish neutrality at the start of the dive, rather than anything to do with reaching the surface from depth after a BC failure. I guess that has some logic to it, but I don't necessarily think it is a robust analysis.

 

[Barefoot_Lawyer]

thanks, so the issue is establish neutrality at the start of the dive, rather than anything to do with reaching the surface from depth after a BC failure. I guess that has some logic to it, but I don't necessarily think it is a robust analysis.

How much more robust of an analysis would you do? What would you suggest is the optimal ditchable vs non-ditchable weight distribution?

 

[johndiver999]

You want to be able to drop enough lead to be able to swim to the surface if your BC is busted. Pretty complex.

 

[Scott G. Bonser]

The YMCA program ended in 2008 and was continued independently as SEI.

I don't know much about the old YMCA program but I read years ago that one of its problems was that the local shops were fiercely independent about instruction, so what happened in YMCA #1 might be different from YMCA #2.

Hey John, Thanks for the update as I mostly frequent PADI and SSI sponsored shops in my area…

 

[franc82]

I'm seeing a of people say "don't need to practice this because I have good pockets, or don't use pockets for weights" or something similar. But your weight belt could get undone accidentally and slip away from you. I saw it happen just a few dives ago. The guy was fumbling with his SMB and it undid his weight belt. He did manage to hold on to it though, fortunately...

 

[inquis]

The guy was fumbling with his SMB and it undid his weight belt.

Perhaps improving SMB skills should be a priority for him?

 

[franc82]

Perhaps improving SMB skills should be a priority for him?

Yes

 

[rsingler]

There is no good reason to have much more ditchable weight then the weight of the gas in your back tank(s) at the start of the dive. If you think you need more than that then you've screwed up something else in your equipment configuration.

That's not quite accurate. Don't forget the buoyancy loss of your wetsuit at depth, from compression of the neoprene. If THAT negative buoyancy, plus the carried gas weight at the beginning of a dive is more than you can swim up, you need to be able to dump more weight.

Thread Info - Optimal Buoyancy Computer

 

[Nick_Radov]

That's not quite accurate. Don't forget the buoyancy loss of your wetsuit at depth, from compression of the neoprene. If THAT negative buoyancy, plus the carried gas weight at the beginning of a dive is more than you can swim up, you need to be able to dump more weight.

Thread Info - Optimal Buoyancy Computer

No, my earlier comment was completely accurate. That's not a good reason to carry extra ditchable weight (although I'm aware that some divers do it). As I already pointed out in an earlier comment, if your wetsuit is thick enough to cause a problem getting up with a failed wing then the correct solution is to use a proper shell drysuit rather than carrying extra ditchable weight. This is part of having a balanced rig.