Too much lift?

[cool_hardware52]

If you have a 17# wing and your dry suit floods,

Who has advocated a 17# wing when diving a drysuit?

I don't get the need to have the smallest bladder that won't provide full redundancy. It's stupid and a fool's errand in my mind.

Using any BC with less lift than your exposure can lose is a needless risk, but vanishingly few exposure suits have more than 30 lbs of lift, and most far less than that.

Tobin

 

[The Chairman]

Who has advocated a 17# wing when diving a drysuit?

I'm not going to name names, but I've seen it done and have heard people brag about how small their wing is. I think it's stupid and I've told them that. In fact, I believe a good friend might have died because of it. A well designed wing can provide a lot of lift without going all taco. They can provide the tiniest amount of lift as well. It's entirely up to what I need for the dive.

 

[Centrals]

The tropical warm water in Philippines can get as low as 18C(65F) if not lower during certain time of the yr. So a 13L/15L tank + thermal protection, a 17lbs wing is pushing the limit for diver with low tolerance to relatively cold water.
I dive with a 30lbs DR wing in SE Asia and do not notice any taco effect at all. Incidentally the wing was also good enough for my very limited dry suit adventure(15L steel tank, 13kg and SS plate).

Horses for courses, by all means has various sizes if you have the inclination and money otherwise compromise is probably the only solution. A wee bit of too much lift/taco effect won't hurt. Scuba diving is a recreational sport not a race so a bit of drag should never interfere with the fun.

 

[Typhon]

You're all speaking of 30lbs extreme maximum for single tank wing and I'm here considering a 42lbs wing (xdeep NX zen) for single tank 7mm wetsuit. Should I be worried ?

 

[cool_hardware52]

I'm not going to name names, but I've seen it done and have heard people brag about how small their wing is. I think it's stupid and I've told them that. In fact, I believe a good friend might have died because of it.

Sorry to hear about your friend. Was there any official determination that an undersized BC was a contributing factor?

Were they using a wing with less lift than 1) The initial buoyancy of their exposure suit, or 2) Max negative buoyancy of their rig?

A well designed wing can provide a lot of lift without going all taco. They can provide the tiniest amount of lift as well. It's entirely up to what I need for the dive.

Examples please.

Tobin

 

[cool_hardware52]

You're all speaking of 30lbs extreme maximum for single tank wing and I'm here considering a 42lbs wing (xdeep NX zen) for single tank 7mm wetsuit. Should I be worried ?

Typhon,

What I have always recommended WRT to required lift is:

1) Any BC needs to offer lift greater than the maximum negative buoyancy of your "rig" . For a BP&W that will be the plate, harness, reg(s), Full Cylinder(s) tank bands and manifold (for doubles), can light + any ballast attached to the rig.

For the typical single rig with a Stainless Plate, and full ~HP 100 steel tank this will be about -18 lbs.

If your wing is smaller than 18 lbs you run the risk of losing your gear if you have to ditch it.

2) Offer lift greater than the maximum possible change in buoyancy of your exposure suit. This allows you to compensate for a fully compressed wetsuit, or the total failure of a drysuit.

In cold water it's almost always the buoyancy of the diver's suit that determines the minimum safe wing capacity, and in warm water it's almost always being able to float the rig.

If one is only diving cold water it matter's little if you oversize the wing a bit. The difference in drag, stability and ease of venting between a 30 and 35 is trivial.

Where it matters is when a diver is trying to use one wing for warm and cold. Careful selection of the cold water wing, i.e. not larger than actually needed, often leaves the diver with a wing that is reasonable to use in warm water too.

In 99% of the cases I've dealt with, which in many many thousands, the key piece of intel is the buoyancy of the cold water suit. Maybe 5 in 100 divers actually know how buoyant their exposure suit is.

How buoyant is your suit? Is it anywhere near 44 lbs? I doubt. Most wetsuits, even 7mm farmer johns are under 30 lbs, and very few drysuits are over 35........

Tobin

 

[The Chairman]

Were they using a wing with less lift than 1) The initial buoyancy of their exposure suit, or 2) Max negative buoyancy of their rig?

She was diving an 18 pound wing and a dry suit. I have no idea if this was a cause or a contributing factor and nothing has been released except that she drowned. I just remember ber going on and on about the small size of her wing.

To date, I've never heard of an accident, injury or death attributed to having too much lift. Ever.

Examples please.

My 44 pound Express Tech works very well. No taco at all. The bungees keep it tamed rather well.

 

[cool_hardware52]

To date, I've never heard of an accident, injury or death attributed to having too much lift. Ever.

A friend of mine is tasked with doing the accident investigation of marine related deaths for a large agency here in So Cal. Boating accidents etc. His portfolio includes scuba. I am aware of several fatalities that were officially attributed to divers being grossly over weighted.


Correlation is not causation, but it's pretty hard to be grossly over weighted while using a BC sized per my often stated recommendations.

Far too many times I hear "if I get a bigger wing can I dive steels with a stainless plate with a rash guard?" or something similar.

IMO It's partly a reflection of the near total lack of proper weighting instruction, and partly a result of BC's with huge lift. Divers get away with being massively overweighted, until the day something goes sideways and panic sets in.

Tobin

 

[The Chairman]

Divers get away with being massively overweighted, until the day something goes sideways and panic sets in.

We disagree on why divers get over-weighted in as much as BCs having much of an impact. Times are changing in regards to weighting and buoyancy among instructors. Over-weighting is a function of instructors feeling a need to plant their students on their knees. As kneeling falls more and more into disfavor, so will the tendency to overweight students.

 

[cool_hardware52]

We disagree on why divers get over-weighted in as much as BCs having much of an impact. Times are changing in regards to weighting and buoyancy among instructors. Over-weighting is a function of instructors feeling a need to plant their students on their knees. As kneeling falls more and more into disfavor, so will the tendency to overweight students.

I never said excessive lift causes over weighting, but it does allow divers to be overweighted, and remain ignorant of the disadvantages and risks associated with being overweighted. Over weighting IMO is mostly a result of too many instructors and dive ops relying on sloppy rules of thumb like "10% of your body weight" in lead.

I applaud all efforts to actually teach proper weighting. Very few of the many newer divers that I speak with have been exposed to much regarding proper weighting. I've always considered it part of my job to make sure my customers understand why I have recommended a particular set of components, and more importantly the conditions under which the goods I've recommended are no longer appropriate.

Tobin