DIR- Generic Drysuit Balanced Rig

[vinsanity]

My training is non-DIR, but the more I read about DIR philosophies, the more I adopt DIR practices. ;-)

I'm building my new BP/W kit. Almost all Balanced Rig discussions seem to go like this:

1. In warm water, if you have a balanced kit, you should not need ditchable weight because you can swim your kit up if the wing fails.
2. In cold water, a drysuit acts as a buoyancy backup if your wing fails, so you shouldn't need ditchable weight here either.

When you run the numbers, the first one makes good sense, and in the case of a wing failure, the second bullet sounds good, but what about if your drysuit floods?

OptimalBuoyancy tells me I need 29 lbs of lead with my drysuit, but with a 30 lb wing and a fully flooded suit, I'll be 15 lbs negatively buoyant. I read a DIR recommend against ever having a single tank wing bigger than 30 lbs.

Soooo... what's the typical DIR direction here? 15 lbs of ditchable weight? Rely on a DSMB for backup buoyancy? Thanks.

EDIT: Corrected statement that 30lb single was not a GUE statement.

 

[OrcasC205]

I have not seen in GUE documentation where they say you should never have more than 30 lbs lift for a singles wing. In fact, the Halcyon 40 lbs Eclipse wing is probably the most popular singles wing among GUE divers in Seattle for the reasons you show above.

Edited to add: I found in "Fundamentals of Better Diving" the passage that you were referring to with the 30 lbs lift for singles. I read it to mean diving with a wetsuit since the paragraph goes on to say that with heavier, larger steel tanks it indicates a more "aggressive" dive that should include a drysuit.

 

[Raphus]

29 lb is a lot of weigth.
The drysuit is not a buoyancy device. But it provides the same buoyancy at every depth. So the wing don't have to compensate for compressed Neopren. (talking about trilaminate drysuit)

So the wing only has to compensate for the air used and the missing buoyancy of the drysuit. In Other words:the rig must be neutral or positive buoyant without the diver in it.
Just try it out.


I use a 32 lb wing. But with only 12 lb(+5lb backplate weigth and a single tank. My rig barely stays above water..
The 40lb might be worth it

 

[vinsanity]

I have not seen in GUE documentation where they say you should never have more than 30 lbs lift for a singles wing. In fact, the Halcyon 40 lbs Eclipse wing is probably the most popular singles wing among GUE divers in Seattle for the reasons you show above.

Oh, you are right. I found it. The GUE documentation says "Wing size and shape is appropriate to the cylinder size(s) employed for training."

It was actually the DIR Wikipedia page where I read that.

In keeping with the minimalist philosophy, buoyancy compensators should be only as large as is necessary to provide neutral buoyancy at any point in the dive, and should allow easy, confident and reliable dumping. The volume should not exceed about 65 pounds (29 kg) for twin cylinders or 30 pounds (14 kg) for single cylinders, on the premise that needing more would be evidence that the rig is unbalanced and unsafe, as the diver should be able to drop excess weight and swim up without a functioning buoyancy compensator. An unnecessarily large bladder volume is considered dangerous as it can contribute to a runaway ascent. Wings with the expansion constrained by elastic cords are also deprecated as they can trap air pockets, making it difficult to get all the air out.​

Sounds like the easy answer. Wikipedia is wrong. ;-) And then that clears it all up. Thanks.

​

 

[Ayisha]

My training is non-DIR, but the more I read about DIR philosophies, the more I adopt DIR practices. ;-)

I'm building my new BP/W kit. Almost all Balanced Rig discussions seem to go like this:

1. In warm water, if you have a balanced kit, you should not need ditchable weight because you can swim your kit up if the wing fails.
2. In cold water, a drysuit acts as a buoyancy backup if your wing fails, so you shouldn't need ditchable weight here either.

When you run the numbers, the first one makes good sense, and in the case of a wing failure, the second bullet sounds good, but what about if your drysuit floods?

OptimalBuoyancy tells me I need 29 lbs of lead with my drysuit, but with a 30 lb wing and a fully flooded suit, I'll be 15 lbs negatively buoyant. GUE documentation recommends against ever having a single tank wing bigger than 30 lbs.

Soooo... what's the typical DIR direction here? 15 lbs of ditchable weight? Rely on a DSMB for backup buoyancy? Thanks.

The Halcyon single 40 lb wing is meant for really heavy tanks, like 120 cf+, though some divers use them for smaller tanks than that.

What the information you quoted refers to is that if you use a larger wing than you need, it will taco around the tank, trapping gas and will be more challenging to release all the gas. Ditto for bungied wings.

The first thing to ensure is that you are correctly weighted.

Can you swim up your rig from depth with a full tank and an empty wing (in case of wing failure)?
If you can't, then you should have some ditchable weight. This could be any ballast that you might happen to be carrying like a can light, large camera, scooter, etc., not just weights.
A balanced rig may or may not include ditchable weight.

The other end of the balanced rig spectrum is at the end of the dive. Can you hold a stop at 10'/3 m with a nearly empty tank and then make a slow, controlled ascent to the surface?
Reach back and feel if your wing is empty or nearly empty or ask someone to check.
If your wing is puffed up at 10'/3 m with a nearly empty tank, you're overweighted.

You would need to do those 2 checks to make sure that you're correctly weighted for both ends of the dive, and to determine if you are knowingly diving unbalanced and need ditchable weight.

Hope that helps...

 

[rjack321]

OptimalBuoyancy tells me I need 29 lbs of lead with my drysuit, but with a 30 lb wing and a fully flooded suit, I'll be 15 lbs negatively buoyant. GUE documentation recommends against ever having a single tank wing bigger than 30 lbs.

Soooo... what's the typical DIR direction here? 15 lbs of ditchable weight? Rely on a DSMB for backup buoyancy? Thanks.

Its not really plausible to end up with a "fully flooded drysuit" that loses all buoyancy... The thicker the suit and more lead it takes to sink the more air it traps

In a single hp100 I have about 38lbs of lead and BP combined. 21 of that is 5lb SS plate, 6lb weighted STA, and the 10lbs on the cam bands. 17lbs in my weight belt.

You need to be able to swim the full cylinders up in case of wing failure at the start of the dive. I have really no problem doing this without ditching the belt at all. Let's say my suit is flooding (also at my heaviest with a full tank), I will use the wing and again swim up. In both cases I will probably ditch the lead at the surface to maintain positive buoyancy, but I dont need to drop it to get back to the surface.

I use a 40lb evolve single tank wing from Halcyon. Not sure where the "30lb max" comes from, the 40lb single of mine is 18yrs old, still made, and still mostly common in cold water GUE-F courses

 

[ginti]

Its not really plausible to end up with a "fully flooded drysuit" that loses all buoyancy... The thicker the suit and more lead it takes to sink the more air it traps

Also, in general, we plan for one single major failure. In other words, the wing fails OR the dry suit fails. In both cases, as soon as we have one of these two major failures, we should call the dive - this is why it is very unlikely to have both of them at the same time.

Anyway, I agree with everyone else here that being able to swim up with your equipment fully empty is a good thing (I personally tried)

 

[johnkendall]

Correct choice of drysuit undergarments will mean that even a fully flooded suit will maintain some amount of bouyancy. This is one of the reasons that for larger dives we often prefer to use thinsulate based undergarments rather than fleece.

Hth
John

 

[PfcAJ]

You wing needs to be able to float your gear on the surface without you in it. If it cannot, some of that weight needs to be ditchable so that it can float. This will certainly cover the unlikely scenario that your drysuit loses every scrap of buoyancy.

 

[jadairiii]

DIR mentality seems to contradict in many ways. ...

It can seem that way if you dont look at the "mentality" as a whole but only piecemeal. What becomes more confusing is that some on forms quote their perceptions of DIR rather then the actual holdings.

Understand that first and foremost, DIR/GUE is based around a unified team. It starts there.