"proper" weighting vs Rock bottom

[limeyx]

I guess more or less what I was after waws, I see people talk about proper weighting. I see the same people talk about rock bottom. They seem to talk about them exclusively and not how they work together. For example, if they are discussing proper weighting they will tell someone to weight themselves for neutral at the surface with 500psi or they will never be able to make a controlled ascent past the safety stop. Unless there was a OOA you would have more air in your tank than that and would not be too light. Likewise, if you weight that way and there is an OOA then you actually need a bit more weight because you are going to be aproaching 0psi and your buddy is already at 0psi. That means you are both light by about 2 pounds each and ascending as a single unit (except for those long hose users).
I, personally don't have any problem with my weighting or using RB. What was getting me was the way I see others talk about the 2 subjects.

Joe

Rock bottom and weighting are 2 completely different concepts and are essentually independent (which is maybe why people don't discuss the two together

Remember, you can always hit zero PSI if you go OOA, so you need to plan for that. Rock bottom is for gas planning, not weighting.

 

[limeyx]

...

Regarding rock bottom you need to consider the range of dives. Rock bottom is fine and dandy on a deeper dive. Let's say you are making a shore dive, you head out, explore some ledges, and you or your buddy reaches a turn pressure and you start making your way back. You are back in the cove in 15 feet of water it's bright warm and critters are everywhere and you each have 750 PSI in your cylinders. In that situation what's wrong with exploring the cove until you are down to 500 PSI or even a little lower? You have an alternate air source well within reach and baring entanglement your bigest risk is a slight surface swim.

The right plan for the right dive.

Pete

There's nothing wrong with that as the rock bottom for almost all tanks at 15 feet is 500 psi anyway just make sure there's nothing you can easily get tangled on and have fun.

I would just suggest that you try to avoid thinking about using the surface air as part of your rock bottom

 

[JeffG]

I would just suggest that you try to avoid thinking about using the surface air as part of your rock bottom

What RB if I'm snorkeling?

 

[TSandM]

"Neutral descent" is kind of a misnomer -- the idea is to keep your buoyancy CLOSE to neutral and manage your descent with your breath. Works fine as long as you aren't trying to get down as fast as you can tolerate because of bad surface current or other conditions.

Lamont, if the ability to hold a 10 foot stop while task loaded was the measure of whether you need more weight, I'd add about twenty pounds . . .

 

[Blackwood]

I'm confused. Neutral descent? :huh:
The phrase "contradiction in terms" comes to mind here for me [IMHO]

One can ascend with negative buoyancy. Likewise, one can descend with positive buoyancy. Just requires some initial force (for example: a fin kick).

That said, TSandM's reply describes my intent in stating "neutral" from the post in question.

 

[magnifica]

proper weighting is gauged at the surface with full gear & tanks. generally, you should float at eye level while your BCD is completely deflated when you have the proper weights

...and as ianr33 mentioned "with an empty tank" (truely empty i.e. 0 bar)

...and while holding a normal breath.

IMO, this is the correct weight.

(can't agree that newbies should be overweighted; this simply makes it harder for them to control their buoyancy)

 

[TSandM]

It's funny for me to see the evolution in the weight I carry over the last 230 plus dives. I started out in class very overweighted, and it was so difficult to control my buoyancy. I worked hard all the way through Fundies (60 dives) to get my weighting down to the minimum I had to carry, and distribute it correctly so I would trim out horizontal. I dove that way for quite a while, and then had some insights into what happens at the end of the dive under some circumstances (eg. while managing a deployed SMB) and added a couple of pounds back. Then I added another pound or so during the winter, to allow me to carry more air in my suit. All was quite manageable (even unnoticeable).

Now I'm diving doubles, which means that, when I descend with full tanks, I'm about 13 pounds negative. The first couple of dives, I had that awful overweighted, awkward, wallowing feeling . . . And then it went away. It's clearly possible to dive fairly severely "overweighted" and be comfortable and not increase one's gas consumption. You just can't do it as a beginner. (I mean, think about the guys who are diving doubled 130's AND carrying stages -- I can't even IMAGINE how "overweighted" they are at the beginning of a dive!)

 

[lamont]

(I mean, think about the guys who are diving doubled 130's AND carrying stages -- I can't even IMAGINE how "overweighted" they are at the beginning of a dive!)

the helium in the backgas cuts down on the weight swing -- another reason why helium is good for you. you can also be a bit underweighted since you'll send your Al80 stages up the upline if you're getting really light.

 

[JeffG]

the helium in the backgas cuts down on the weight swing -- another reason why helium is good for you. you can also be a bit underweighted since you'll send your Al80 stages up the upline if you're getting really light.

We use them in fresh water using nitrox. If you are not paying attention.....can you say dirt dart.

 

[limeyx]

the helium in the backgas cuts down on the weight swing -- another reason why helium is good for you. you can also be a bit underweighted since you'll send your Al80 stages up the upline if you're getting really light.

Even with 21/35 and 21/35 in an 80 and 50% in the 40, my 40 pound explorer was a bit underpowered. Might be time to look at a new wing.