Advice

[fisheater]

Also, those vacation DMs will likely figure that you know what you're doing when you show up with your BP/W.


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[g1138]

~ wing "faceplant" on post-dive surface floats is another (which can't universally be neutralized through countermeaures of steel tanks or weighted STAs).

-hh

Simply a diver skill issue rather than a gear issue. It's either over-inflation of a high lift capacity wing, or the diver is incapable of relaxing and leaning back. Diver's experienced with wings and back-inflates don't have this problem. Most new divers overcome it when told to lean back or deflate a little.

 

[JamesK]

Simple. If cave is in your future, start using the gear that works for it. BPW or a side mount setup. Anything else is a waste of money, time, and effort.

I don't see any downfalls to a BPW setup for rec diving. The so called downfalls are simply absurd. Everything has already been figured out because any dive you want to do has already been done by many in a BPW. So things like storage and weighting and all the other issues people try to point out are now a non issue.

Face planting in the water is a non issue as well. Many people want to make it seem like you will be at the surface struggling to keep your head out of water. Yeah, no.

 

[divad]

Faceplant!? My problem is fully inflating the wing and laying around on my back until I almost fall asleep.

 

[-hh]

Yes,

• if you dive with Steel tanks, it reduces the magnitude of the effect;

• if you dive with heavy thermal protection, this increases buoyancy upfront and reduces the magnitude of the effect;

• if you dive with all your weight behind you (such as with a weighted STA), it reduces the magnitude of the effect;

• if you minimize your 'freeboard' displacement above the waterline, it redues the magnitude of the effect;

But:

• if you're diving with an AL80 tank such as at a vacation dive resort;

• if you're diving in the tropics, your thermal protection's buoyancy is minimal;

• if your thermal protection is minimal, you have fewer weights at all with which to position for trim;

.. these mitigating strategies do not exist to be applied to resolve the problem.


Plus, there can be other non-mitigating factors, such as a negatively buoyant UW camera:

• being negative, it will require additional BC lift for the same amount of 'freeboard';

• being nominally held in front, the negative mass is given a moment arm that also creates torque

Simply a diver skill issue rather than a gear issue. It's either over-inflation of a high lift capacity wing, or the diver is incapable of relaxing and leaning back. Diver's experienced with wings and back-inflates don't have this problem. Most new divers overcome it when told to lean back or deflate a little.

I've heard these sorts of things claimed before too.

I've done the centroid analysis using my Mechanical Engineering degree...it is a straightforward "Torque Balance" equasion. We could replace the diver with a manequin and get the same outcome.

Second, the "leaning back" can be partly body position/posture, but it still comes back to the torque. Said torque may be counteracted by a diver during a float through motion, but motion invokes an energy input...it again depends on magnitude and for how long it must be managed, but fatigue & distress is an eventuality. So while an in-shape diver may be able to be fine skulling for a half hour, someone else might fatigue out far more rapidly...do check the archives for where I've discussed a rescue I performed in Bequia back in 2003 of just such a fatigued-out diver and what were some of the factors involved.

Third (and BTW), a similar claim is "oh, just flop over onto your back", but sea conditions must be favorable to do this.

Fourth, there certainly are some things where experience does help...such as in not being particularly perturbed by as low as an eye level float. I don't dispute that there's some people out there that never fully get comfortable being in the water that can exasperate some problems. However, such indivduals do not constitute 90% of all divers...or even 50% from what I've seen... so we need to stop trying to use this excuse as a chronic crutch to deny that there might be something real behind a particular observation or complaint.


-hh

 

[fisheater]

Warm water trip. Empty (really empty!) aluminum tank, minimal exposure protection, negative camera system, steel backplate. NO FACEPLANT!

Also, NO weight overcharges.


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[divad]

Yes,

• if you dive with Steel tanks, it reduces the magnitude of the effect;

• if you dive with heavy thermal protection, this increases buoyancy upfront and reduces the magnitude of the effect;

• if you dive with all your weight behind you (such as with a weighted STA), it reduces the magnitude of the effect;

• if you minimize your 'freeboard' displacement above the waterline, it redues the magnitude of the effect;

But:

• if you're diving with an AL80 tank such as at a vacation dive resort;

• if you're diving in the tropics, your thermal protection's buoyancy is minimal;

• if your thermal protection is minimal, you have fewer weights at all with which to position for trim;

.. these mitigating strategies do not exist to be applied to resolve the problem.


Plus, there can be other non-mitigating factors, such as a negatively buoyant UW camera:

• being negative, it will require additional BC lift for the same amount of 'freeboard';

• being nominally held in front, the negative mass is given a moment arm that also creates torque

I've heard these sorts of things claimed before too.

I've done the centroid analysis using my Mechanical Engineering degree...it is a straightforward "Torque Balance" equasion. We could replace the diver with a manequin and get the same outcome.

Second, the "leaning back" can be partly body position/posture, but it still comes back to the torque. Said torque may be counteracted by a diver during a float through motion, but motion invokes an energy input...it again depends on magnitude and for how long it must be managed, but fatigue & distress is an eventuality. So while an in-shape diver may be able to be fine skulling for a half hour, someone else might fatigue out far more rapidly...do check the archives for where I've discussed a rescue I performed in Bequia back in 2003 of just such a fatigued-out diver and what were some of the factors involved.

Third (and BTW), a similar claim is "oh, just flop over onto your back", but sea conditions must be favorable to do this.

Fourth, there certainly are some things where experience does help...such as in not being particularly perturbed by as low as an eye level float. I don't dispute that there's some people out there that never fully get comfortable being in the water that can exasperate some problems. However, such indivduals do not constitute 90% of all divers...or even 50% from what I've seen... so we need to stop trying to use this excuse as a chronic crutch to deny that there might be something real behind a particular observation or complaint.


-hh

Are you suggesting that out-of-shape divers shouldn't dive, or that they should use some sort of crutch?

 

[beaverdivers]

Go w/ an adjustable B.C.

BK/Plate w/ wing, front adj or back adj.

Which ever you like?

 

[j2s]

"Begin as you mean to go on . . . "

If cave is your eventual goal, you will be more efficient in your gear purchases, if you buy something now that won't be difficult to adapt to cave diving later. Although sidemount seems to be the flavor of the month, I'd be willing to bet that the majority of cave divers still dive backmounted doubles. If you buy a backplate and wing system now, then all you need to change to go to doubles is to buy a doubles wing, and all your gear will be familiar to you. If you buy something now that can't easily adapt to carrying doubles, you will have to learn another gear setup when you make the transition, whether it's to backmount or sidemount.

Ditto....One bp and two wings, one for singles/one for doubles [or the Apeks WTX4 like a few others can be used for both]... BP/w's are easy to travel w/and more cost effective in the long run...Take a look at Deepseasupply's 'Kydex' bp's.......Can be used for a wide range of 'environments'....Versatile, customize-able, light weight for travel.....You'll pay a little more now, but a lot less in the end......And the resale value is a whole lot better !!!.......

 

[Jim Lapenta]

I like how a BPW is going to do things that are simply not true to a properly weighted diver and one who has been shown how to properly set it up. I work with a lot of the stuff that engineers come up with and the calculations involved. One in fact just yesterday that the engineer refused to correct. So instead of a part that had nice closed circles in a graceful arc around one corner. He insisted his dimensions were correct. So we went with them after sending a drawing from our CAD system that met his requirements. On Monday morning he will get his funky saw blade. Calculations on some computer program do not always reflect real world applications. Most of the experienced ,machine shop guys I know hate engineers. We have to figure out how to make their ideas work for real. Some simply won't.

And I've never seen a mannequin that can make minute adjustments in it's body position. Unless the Japanese have something new out.