Question about “balanced rigs” and having all ballast unditchable

[MichaelMc]

As I have pointed out several times in this thread, if you are perfectly weighted, you only need to be able to ditch the equivalent weight of the air you might use on the dive. If you are perfectly weighted and end the dive on the surface with an empty tank, you should not be able to descend again. If your tank is near empty during a safety stop, you should have a hard time holding that stop with your BCD perfectly empty--your body will be heading to the surface, and you will be fighting to stay down.

I would quibble with our empty tanked diver's surface situation. Assuming SS was targeted with a pound of air, the empty tanked surface diver has buoyancy of 1 lb. + suit expansion from SS to surface. Let's set aside neutral suits. If a 3mm suit has 6 lb. buoyancy (?), losing 2 lb. at 15' (?) puts our diver at +3 lb. Women have 2 lb. expiratory reserve, so that and a dive makes descent easy if moderately skilled. Diving a few pounds heavy erodes most of that +3 lb. surface buoyancy leaving our diver with head awash or treading. Having that gas weight ditchable will help our empty diver, though still leave the full tanked diver with (edit-> ) only the top of their head bobbing out of the water. Not bad, but not so rock solid on the surface they are not able to descend.

 

[Chavodel8en]

What that means is that if you use a 7mm wetsuit beyond 18m depth, then you will need either ditchable weight or redundant buoyancy.

I agree with this.

But I think the poster was saying: "One SHOULD NOT dive a 7mm wetsuit beyond 18m, because it will necessitate carrying TOO MUCH ditchable weight (too much ditchable weight defined as more than the weight of the gas used). (Again apologies if I misstate his points)

To which I would take issue. Weight of gas used would be ~ 5 lbs. I want a bit more ditchable weight than that - enough to account for the suit compression.

 

[CT-Rich]

Here is an observation on wetsuit diving. When I was a young Paleolithic diver wanting to dive 33 m, the question was never about suit compression. It was about the lift capacity of your BCD. I was diving with a 1/4 inch farmer John wetsuit. It was so stiff that you were counting on suit compression making it more flexible. If your suit neede 28 lbs to get off the surface, you needed at least 28 lbs of lift. Pretty much everyone was diving Al 80s, cause they were the hot gear at the time. If you needed to, your implicit buoyancy back-up was weight dropping, not that I thought about it much at the time.

Your “balanced” rig is actually very limiting, because you are saying that it shouldn’t be used below 18 m. What happens to the diver that gets caught in a down current to 45 m? Suit compression has totally screwed this diver if the lift of his BCD is less than the negative buoyancy of their steel back plate, tank and fixed ballast. He will not be able to swim up his rig.

The qualifications you keep coming up with don’t really reflect real life. He is not going to need to submerge to avoid a speed boat. Ditchable weights don’t fly off your body if you kit-up properly. The likelihood of a stupid error ( accidentally not turning your air on is just as/more likely losing a weight pouch or belt). Exhausted divers on the surface waiting For a pick up are not going to want to worry about how effiently they are using air at 15 m, nearly as much as they are going to want their face out of the waves.

Live and let dive, but I don’t see this as optimal strategy.

 

[Eric Sedletzky]

Wow! These 5 mil then to a drysuit people would absolutely freak out and run away screaming never to be heard from again if they ever saw me in my 1/2” urchin suit with my steel 120, steel back plate, and a big honkin’ weight belt!
When I was up at Albion over the weekend doing the Urchin removal dives, I sure wished I brought it. I wore my 7mil instead. The surge was whipping us around and I even got a few spines here and there. 52 degree water.
It would have been hysterical to see someone attempt to do what we were doing in a drysuit.

 

[AJ]

Your “balanced” rig is actually very limiting, because you are saying that it shouldn’t be used below 18 m. What happens to the diver that gets caught in a down current to 45 m? Suit compression has totally screwed this diver if the lift of his BCD is less than the negative buoyancy of their steel back plate, tank and fixed ballast. He will not be able to swim up his rig.

You could turn this around: dive the gear you need for the dive. I know this is more of a technical mindset than a rec mindset, but it's the choice everyone has to make. For me, if my rig won't allow me to do the dive I want to do I would change my rig or do not do the dive. If ditchable weight would make my dive safe I might consider doing that dive as long as it does not give me other issues like being out of trim (due to constricted position to put the weight). Personally I prefer to adjust my rig for the dive or don't dive at all.

Reading all those threads it seems to me there are divers who adjust their gear to the dive planned with no compromises (tech style?), while others do all their diving with the same gear they have (Rec style?). Nothing wrong with either as long as it's safe.

 

[CT-Rich]

You could turn this around: dive the gear you need for the dive. I know this is more of a technical mindset than a rec mindset, but it's the choice everyone has to make. For me, if my rig won't allow me to do the dive I want to do I would change my rig or do not do the dive. If ditchable weight would make my dive safe I might consider doing that dive as long as it does not give me other issues like being out of trim (due to constricted position to put the weight). Personally I prefer to adjust my rig for the dive or don't dive at all.

Reading all those threads it seems to me there are divers who adjust their gear to the dive planned with no compromises (tech style?), while others do all their diving with the same gear they have (Rec style?). Nothing wrong with either as long as it's safe.

So, until you can afford a dry suit, AOW is off the board? This seems incredibly narrow. I am going to take this a little off the rails now....

If I can’t dive in perfect trim, I won’t dive at all? What do you do if decide that you want to skip the hood and gloves? Dismantle and reconfigure your gear? Do a weight check every dive?

This philosophy of “balance” seems like it will be some of the dullest diving ever. They have all of these restrictions about types of gear and if you can’t afford it, you are beached. And some of those restrictions, like ditchable weight won’t even make you safer.

It’s a bit driving I guess, their are people who like to drive and their are people that like cars and enjoy the tinkering.

 

[AJ]

So you're rather going to dive with inadequate gear and skills than using the right equipment for the dive? For me there's nothing to die for down there. So yes, if I can't do the dive the way I should then I won't dive. Doesn't matter what dive it is.

I come here for fun and I like to learn from others arguments and experiences. There's no fun in this thread anymore. Therefore I'am abandoning this disscussion because to me this is like it's heading for an almost religous debate. Not interested in that kind of discussion. Have fun and dive safe.

 

[CT-Rich]

So you're rather going to dive with inadequate gear and skills than using the right equipment for the dive? For me there's nothing to die for down there. So yes, if I can't do the dive the way I should then I won't dive. Doesn't matter what dive it is.

I come here for fun and I like to learn from others arguments and experiences. There's no fun in this thread anymore. Therefore I'am abandoning this disscussion because to me this is like it's heading for an almost religous debate. Not interested in that kind of discussion. Have fun and dive safe.

Hmmmm... at what point did I say anything about inadequate skills? Or equipment for that matter? When planning a dive you ask are conditions going to exceed my training? You also have to ask do I have I have sufficient reundancy in case something goes wrong. The two primary parts of redundancy are GAS and BUOYANCY. For gas, you have a pony, or a buddy and gas planning. For buoyancy you have a BCD and ditchable weights. In open water, diving you should never put yourself in a situation where you lack that redundancy. Special gear and training are needed for any over head environments (either real, like a wreck or cave, or virtual, like deco).

While making a big deal about something that is mostly a personal comfort issue (exposure suit) as the limiting factor so yo can disregard what is an essential safety factor (redundant buoyancy), seems to be putting concerns in the wrong order. Lots of divers can afford a 7 mm wetsuit, but not a drysuit. My concern would be if they were planning dives where they would be stuck on the bottom without a specific plan of how to get to the surface should they have a catastrophic BCD failure. A steel tank on a steel backplate would, honestly, be a concern for diving 30 m in a wetsuit. Ditchable ballast is the most reliable form of redundant buoyancy available. If it is parced out so it can be dumped in increments, all the better.

Concerns about panicked divers rocketing to the surface, overweighting with ditchable ballast or accidental loss of ballast are much more about training than gear.

 

[leadduck]

I think some divers wrongly believe that ditching weight at depth will cause an immediate fast ascent and should be avoided at any cost. That's dangerous because in some situations ditching weight at depth is just the right thing to do and does not impede a normal safe slow ascent. You need just as much weight ditchable that you can swim up against the rest. Of course you'll be positive in shallow water then and have another problem, but an easier one to solve compared to being very negative at depth. Grab the anchor rope, a stone, or your buddy, to complete the safety stop.

As a wet suit diver with a BCD malfunction you could also hand over some of your weight to your buddy, then both swim up until you become positive, then take it back. It's safer if the diver with a BCD malfunction is positive and held down by his buddy or a stone or the anchor rope, than being negative. Because if they loose contact, in the latter case the victim-to-be will descend with no working BCD, and that has happened too often.

 

[Bob DBF]

And it's not about whether there is weight on a belt. I use a weight belt when I need the weight (only underneath my crotch strap so it can't accidentally drop).

Glad to see you are not against ditchable weight, I don't plan on using it either.
Well the belt won't drop to the bottom, but it's a pita to get back on. I had mine drop as I was walking into the water, which turned into a fustercluck, but that is another story.

I think that Balanced Rig as a term and concept is propably relatively widely misunderstood, or unknown...

Perhaps refraining from pointing out how bad other points of view are and clarifying your own would help the situation. As far as I can tell from reading, a balanced rig is one with redundant buoyancy rather than needing proper weighting, which is more of a tech issue.

I think that the big issue with diving deeper than 18m with a thick wetsuit it that most divers doing that have no idea what kind of trouble they could be in if there was a loss of BC. I have a plan, some half assed redundant buoyancy, and a bit of experience so I'm figuring I have a better than average chance of posting on ScubaBoard after the incident.



Bob