Ditchable weights...are they needed and is there a minimum?

[nereas]

sounds like im screwed with those tanks.....

Exactly.

Wetsuit diving involves making sure you are not overly dependent on your wing, since you do not have a back-up buoyancy device such as a drysuit. Thus, wetsuits are normally combined with aluminum tanks, for safety. Aluminum tanks are not as negative when full, and they act as an elevator when close to empty.

Wetsuits and steel tanks are not a good idea together, unless you also get a double-wing or a dual-bladder wing to go with it. This at least gives you redundancy for the wing. Although it is still not completely safe.

However, 300bar has pointed out in other threads that the Dutch dive the North Sea with wetsuits and steel tanks all the time, and they are not dying in droves there either. This fallacy however is one of popular appeal, since what the Dutch are doing in Dutchland has nothing to do with your safety in the PNW. I cannot say whether the North Sea has walls and canyons?

And you need to imagine yourself in your wetsuit at a depth where suit compression has eliminated your suit buoyancy. And you must be able to ditch enough lead to become neutrally buoyant in case of a wing failure.

Wings do not fail that often. But you don't want your life to depend on a remote possibility either.

There is a lot of talk about "kicking up." Few people however have ever tried doing this. It is certainly not easy. And if you were on a wall, and you could not do it, then the descent into oblivion would be unstoppable. And this does happen to divers, although mostly when they are narked and out of air and too deep, all at the same time.

 

[JeffG]

nereas and I have the same basic philosophy, we just differ on how we put it into practice.

Mainly because you dive and he uses google.

I can only see his "echo", but I have a good idea what he states. Its a "rule of thumb" where a divers ditchable weight equals the weight of a divers backgas. This works on some kits, but doesn't make sense in others. (See Nereas post where he add's weight to his belt because he uses double 130's, but all he does is make himself even more negative.

But getting back to the idea of a balanced rig (which is really what this thread is talking about). The whole discussion shows that its the thick wetsuits that are the problem. Its their buoyancy properties that help create this potential dangerous situation and add in the fact that their thermal protection (or lack thereof) has the same pattern. (offers nothing at depth)

Why people use thick wetsuits is beyond me.

 

[300bar]

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We have some very wise but completely OFF TOPIC words in this thread.Please live by them and get back to the topic from OP
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[PerroneFord]

Why people use thick wetsuits is beyond me.

Because they are a LOT cheaper than a good drysuit. Same reason why we see so many other obfusticated solutions in diving.

 

[JeffG]

Because they are a LOT cheaper than a good drysuit.

Some drysuits have come down in price. (Like the Bare Next Gen).

Same reason why we see so many other obfusticated solutions in diving.

Yes. Sad but true.

 

[300bar]

Then again, as 300bar has pointed out in other threads time and again, thick wetsuits are quite popular in some parts of the world.

They are indeed on this side of the globe.Mainly for "shallow"diving.
10 to 20m.Below that you don't.Just to freaking cold.

 

[nereas]

They are indeed on this side of the globe.Mainly for "shallow"diving.
10 to 20m.Below that you don't.Just to freaking cold.

For a gently sloping beach dive, I agree, there is little risk with a thick wetsuit and steel tanks and tons of other nonditchable weight, since you could always simply crawl back up the beach underwater if you needed to.

And for shallow diving, the suit compression simply does not become an issue, either.

The walls and canyons are where thick wetsuits can be lethal, however. Someone dies somewhere in the world with this combination every year, although normally it is caused rather by going too deep, getting narcosis, using up or dumping air, and then spiralling away. The latest case was over the past weekend in San Diego, according to some of the other dive boards, and here:

http://www.scubaboard.com/forums/3879674-post1.html

 

[Charlie99]

Does anybody have the empty buoyancy spec for a Hesier 95???

An incredibly negatively buoyant tank is probably the root cause of the original poster's problem.


Divechk -- did you ever do a proper weight check with the new tank? It sounds like you will be grossly overweighted even without any lead. The problem is not having enough ditchable weight. Your problem is being grossly overweighted even without ANY lead.

If you are properly weighted with 8 pounds of lead and an AL80 (with is about 4 pounds positively buoyant when empty), then you will be properly weighted with zero lead if your new tank is 4 pounds negatively buoyant when empty, and overweighted if it is moer than 4 pounds negative when empty (Which since it is a Heiser, it most likely is).

Charlie Allen

 

[Brewski]

Does anybody have the empty buoyancy spec for a Hesier 95???

An incredibly negatively buoyant tank is probably the root cause of the original poster's problem.


Divechk -- did you ever do a proper weight check with the new tank? It sounds like you will be grossly overweighted even without any lead. The problem is not having enough ditchable weight. Your problem is being grossly overweighted even without ANY lead.

If you are properly weighted with 8 pounds of lead and an AL80 (with is about 4 pounds positively buoyant when empty), then you will be properly weighted with zero lead if your new tank is 4 pounds negatively buoyant when empty, and overweighted if it is moer than 4 pounds negative when empty (Which since it is a Heiser, it most likely is).

Charlie Allen

I couldn't find a spec sheet for this online. I was able to find XS, PST, and Luxfer but not Heiser.
I did find this source: http://www.cavediver.com/resources.htm

But there is no bouyancy info just dry weight.

Seeing how much more bouyant the larger heiser tanks are compared to the other popular mfg. I believe your right.

Charlie Allen[/quote]

 

[micklock]

Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan