How much ditchable weight is best?

[DrSteve]

I'm switching to a BPW. Of course this means I will lose a significant amount of ditchable weight if I get a SS plate. In the tropics I might be diving with as little as 4-6lbs. Locally it will be more like 10-12 lbs. With an Al plate I'd clearly be carrying 8lbs at a minimum (ditchable)

I know you shouldn't dive over weighted. But I also know you shouldn't dive with too much unnecessary weight. So the big q is...how much ditchable weight is "recommended"?

Thanks.

 

[jonnythan]

Why would you need to ditch weight?

 

[DrSteve]

Why would you need to ditch weight?

Assuming I end up in an emergency situation where I have no choice. BC failure for example.

 

[jonnythan]

You should be able to swim your rig up from depth in the event of a total BC failure.

Ditching weight is an unacceptable alternative since it will make you uncontrollably positive as you get towards the surface.


Also... if carrying ditchable weight, only carry as much as you need. If you're perfectly weighted (neutral at the surface with an empty tank), adding extra ditchable weight doesn't accomplish anything.

 

[DrSteve]

You should be able to swim your rig up from depth in the event of a total BC failure.

Ditching weight is an unacceptable alternative since it will make you uncontrollably positive as you get towards the surface.

Also... if carrying ditchable weight, only carry as much as you need. If you're perfectly weighted (neutral at the surface with an empty tank), adding extra ditchable weight doesn't accomplish anything.

What you are saying makes a lot of sense. But, here I am remembering being at 120 feet and sinking, I finned as hard as I could and remained in one place. My buddy came over and puffed some air in my BC and from neutral I had no problem with finning up. I know my weighting was good because we checked it before the dive (I think I needed about 16 lbs to be neutral at the surface with an empty BC). So while I agree that any diver should be able to swim up from neutral buoyancy at any depth, if the BC has failed it doesn't seem like that would be possible.

 

[jonnythan]

At 120 feet, you should only be negative by the weight of the gas in your tank and the lost buoyancy of your wet suit.

What kind of suit and tank were you diving?

A proper weight check can only be done on an empty tank.

 

[JeffG]

What you are saying makes a lot of sense. But, here I am remembering being at 120 feet and sinking, I finned as hard as I could and remained in one place. My buddy came over and puffed some air in my BC and from neutral I had no problem with finning up. I know my weighting was good because we checked it before the dive (I think I needed about 16 lbs to be neutral at the surface with an empty BC). So while I agree that any diver should be able to swim up from neutral buoyancy at any depth, if the BC has failed it doesn't seem like that would be possible.

Were you wearing a thick wetsuit?

 

[DrSteve]

At 120 feet, you should only be negative by the weight of the gas in your tank and the lost buoyancy of your wet suit.

What kind of suit and tank were you diving?

A proper weight check can only be done on an empty tank.

I had an Al80 (which was about half full, so should have been more buoyant than when I started, although still negative at that point) and a 7mm farmer john.

 

[jonnythan]

The thick wetsuit at 120' is the culprit. In a nutshell, that's not going to be DIR for exactly the reason you experienced.

 

[DrSteve]

The thick wetsuit at 120' is the culprit. In a nutshell, that's not going to be DIR for exactly the reason you experienced.

OK that makes sense...so in *my* case it is safer for me to dive with some ditchable weight. Had I dropped the 12 lbs I had ditchable, or even just dropped one weight bag at a time, I would have been able to get back to the surface. Also...I'm not a DIR guy, but I do figure that those of you who are, have a more rigid set of rules to follow than most divers bother with.

Thanks!