Hogarthian rig balancing

[2airishuman]

This might not be an appropriate question for the advanced board, but I'd like an advanced person to answer.

Heh. Advanced people. I'm not one, but I'm replying anyway, because I dive a 7mm suit, stainless steel backplate, and HP120s.

I'm primarily diving wet in Southern California in a 7mm suit. I use a wing and stainless steel back plate. I'm usually diving a big single steel tank like an HP120, sometimes a spun steel Asahi 120 that is -5 lbs buoyant empty and -13 lbs when full. Assume my suit is maybe 16 lbs buoyant and compresses and my gas weighs ~8 lbs.

My first piece of advice is to sell the Asahi 120 to someone else. The weight and trim problems posed by the thick bottom are difficult to manage. You will be happier than you would with a big wing.

Most other 120s are neutral when empty, +or- a pound or so.

My question is, why are positively buoyant floatation materials not attached to a HOG rig to adjust rig buoyance in a less flocculating, more fail safe, and more streamlined manner than through an air inflated wing? It seems like the optimal wing size is achieved when the rig's buoyancy is equal to the potential worst case buoyancy loss.

I believe you mean fluctuating, not flocculating.

Floats that don't compress can be improvised. Spearfishing people, for example, use them to bring fish to the surface. Usually a plastic shell pressurized enough that it will not compress at the intended maximum depth. You could also use a low-pressure steel tank. As others have indicated, it is nearly always preferable to switch your gear so it isn't so negtative.

 

[KevinNM]

There some tragic stories of tech divers with many steel tanks and wetsuits diving deep and finding they couldn't get off the bottom. The most horrific one I know of was the Diver's Supply disaster that killed Andre Smith, Michael Elkins, and John Claypoole in 1998.

 

[eelnoraa]

I figure I need enough wing lift to:
1) compensate for protection change (16 lbs worst case)
2) at least equal the weight of the gas I will consume, so I can start the dive that negative and stay neutral at my safety stop
3) float the rig if I'm not in it

this true for determining lift. Not enough to archieve balanced rig. You will need these:
a. empty tank, empty wing, you should be neutral at surface or safety stop depth.
b. With full tank, empty wing, at depth, you need to be able to swim up.

Having positive material attach to rig may change the life capacity, but may not change the balanceness. In fact, if the positive material is compressible, it will make the rig even more unbalanced. If you think about it, the main reason for your rig to be unbalance is your wetsuit, which can lose its buoyancy at depth. So more compressible material will only make it worse. what is the positive material are you considering?

 

[Bob DBF]

Not being able to get to the surface because you went too deep in a wetsuit and had no ditchable weight would really suck.

Back in the olden days, I learned you always had ditchable weight until you were in your wetsuit and Mae West. The first was the weightbelt, and the next was your rig. It is interesting to me that now, due to larger tanks, that this concept has not survived or reappeared. Granted if the BC is fine you surely don't want to give it up, but once it can't do it's job it is just a hindrance.

The concept of a ditch and CSEA / buoyant ascent was to solve the problem being discussed, as it could happen then, although not as likely.

 

[Bob DBF]

what is the positive material are you considering?

I gave him a solution in post #9. They have materials that will hold buoyancy with depth ratings from 200m to 6000m. I think it's over overkill but it will work.

Products | DeepWater Buoyancy

If these guys don't have it off the shelf, they can do custom work.

Bob

 

[lowviz]

I gave him a solution in post #9. They have materials that will hold buoyancy with depth ratings from 200m to 6000m. I think it's over overkill but it will work. ...//...

Yes, would work. But as much as I hesitate to post in this thread, I feel that a basic idea isn't being clearly stated.

Hogarthian is not DIR. GUE and UTD appear to have embraced many Hogarthian ideas and made them their own. The OP claims to be a DIR practitioner. Problem solved. Your people have it all solved to the Nth degree. I will also agree that their limited equipment selections will nearly guarantee a balanced rig.

I like to dive a collection of gear. Not trying to sell this to anyone, just works for me. Some gear collections cannot be balanced. Simple, I don't dive them anymore.

 

[kammel78]

The deeper you go using a wetsuit the more you have to think about lift, and also if you can bail yourself out if your wing ever crapped out. Not being able to get to the surface because you went too deep in a wetsuit and had no ditchable weight would really suck. For this reason a lot of people that dive wet and go deep believe in ditchable weight, but then that brings up the whole fast ascent to surface and getting bent thing, or better bent and alive debate.
Probably not a good idea to go too deep wet.

There some tragic stories of tech divers with many steel tanks and wetsuits diving deep and finding they couldn't get off the bottom. The most horrific one I know of was the Diver's Supply disaster that killed Andre Smith, Michael Elkins, and John Claypoole in 1998.

In the context of this conversation and general advice to not dive deep wet...can someone define deep?

 

[DevonDiver]

yup, and it's one word, Drysuit. IIRC they don't advocate diving thick wetsuits period, and they don't advocate diving steels in wetsuits.

Ditto..... and that's an underlying principle in the 'balanced rig' concept. Bear in mind that 'once-upon-a-time' there wasn't any insistence on drysuit use.... the balanced rig was meant to take care of all eventualities...

"A diver must start with a balanced rig which gives him every chance to deal with emergencies. In ocean or lake diving, steel tanks should never be used without a drysuit. Double wings are an invitation to a disaster - do not use them. Elastic wings are a disaster waiting to happen. They can not be operated safely by mouth, they lose their gas if ruptured, they can not be breathed like normal wings, and they cause more drag than normal wings. For ocean, aluminum 80's are the tank of choice. If more gas is needed, take an aluminum stage, but don't risk your life being over weighted at the beginning of the dive. The buoyancy characteristics of aluminum, especially when using helium , are such that a weight belt and or canister light will provide the necessary ballast which can be dropped in an emergency, making the rig only reasonably negative when full, neutral when empty, but swimable by dropping the weight. In cave, steel must be used with a drysuit and they must be negative enough to allow the diver to stay down in a low on gas emergency. There is nothing worse than being too light to stay off the ceiling while low on gas and then struggling. For this reason, the rig must be balanced to a no gas situation prior to cave use, and weighted accordingly".
George Irvine - Doing It Right Gear Configuration​

Here's my article on balanced rigs.. The Balanced Rig

 

[Eric Sedletzky]

In the context of this conversation and general advice to not dive deep wet...can someone define deep?

Deep enough to be at the limit of being able to swim up a rig with no ditchable weight. That can mean a lot of different things factoring in thickness, and type of material. Thinner suits lose less overall buoyancy therefore you can go deeper and still manage to kick up with no air in wing. Thick suits lose a lot of bouyancy, and cheap thick suits will lose even more buoyancy than the old American made Rubatex which was the most crush resistent neoprene ever made. I have a suit that is the current most dense material made for commercial use (Korean stuff) and it loses way less buoyancy than a cheap suit which will crush down to nothing paper thin and be shot after half a dozen deep dives. So there is a lot to factor in.
Personally, I don't believe in having all my weight on the rig. First of all I have no place to put it, and second I like having ditchable weight in an emergency.
People have been diving wet since the beginning of diving in my region (1950's). That's just the way we do it. There are several reasons for that. First, wetsuits are relatively inexpensive and in our environment gearing up on rocks and doing a lot of trail hiking to get to spots, plus a lot of gnarly beach entries and exits not to mention rocket entries and the need to crawl over stuff many times to get in or out mean that drysuits will take a beating and are generally more tender to deal with than a rugged wetsuit. The other thing is hassle factor, wetsuits are quick and convenient. The last thing is that so many people around here freedive anyway that they're used to wearing wetsuits and many times will do a tank dive then do a freedive, so needing two different suits and having to clean two different suits at the end of the day just becomes a bigger hassle. Also a lot of people here go on multi day camp/dive outings, it's just a way of life on the North Coast. A wetsuit you just pull the thing on day after day and re- wet it, it doesn't care. You can be in it all day kayak diving, freediving, whatever. Drysuits need a lot more TLC and then there's undergarments, sweat, seepage, etc.
So you can see the appeal of why we use wetsuits.
And BTW, almost everyone I know who dives wet and owns their gear uses steel tanks. One way we can tell who rented their gear is by the aluminum 80.

 

[Eric Sedletzky]

Ditto..... and that's an underlying principle in the 'balanced rig' concept. Bear in mind that 'once-upon-a-time' there wasn't any insistence on drysuit use.... the balanced rig was meant to take care of all eventualities...

"A diver must start with a balanced rig which gives him every chance to deal with emergencies. In ocean or lake diving, steel tanks should never be used without a drysuit. Double wings are an invitation to a disaster - do not use them. Elastic wings are a disaster waiting to happen. They can not be operated safely by mouth, they lose their gas if ruptured, they can not be breathed like normal wings, and they cause more drag than normal wings. For ocean, aluminum 80's are the tank of choice. If more gas is needed, take an aluminum stage, but don't risk your life being over weighted at the beginning of the dive. The buoyancy characteristics of aluminum, especially when using helium , are such that a weight belt and or canister light will provide the necessary ballast which can be dropped in an emergency, making the rig only reasonably negative when full, neutral when empty, but swimable by dropping the weight. In cave, steel must be used with a drysuit and they must be negative enough to allow the diver to stay down in a low on gas emergency. There is nothing worse than being too light to stay off the ceiling while low on gas and then struggling. For this reason, the rig must be balanced to a no gas situation prior to cave use, and weighted accordingly".
George Irvine - Doing It Right Gear Configuration​

Here's my article on balanced rigs.. The Balanced Rig

I don't mean to be disrespectfull to G.I. And the whole DIR philosophy regarding using steel tanks wet, but this statement is utter rubbish.
Regardless if a diver is using a steel or aluminum tank, their OVERALL weighting is balanced accordingly, and as long as the diver (IMO) has enough ditchable weight using a steel tank to reach the surface and still not be too heavy at depth there is absolutely no difference. In the end, the result of being able to hold a stop at 15' with an empty wing and a near empty tank is what we're shooting for. The rest of the combo doesn't matter. In fact, the steel is better because it allows for less ditchable weight but still enough to reach the surface at a much more managable ascent rate. Plus they trim out better.
I think where that whole G.I. Philosophy comes from is technical cave diving with steel doubles which doesn't apply to 99% of us.