BP/W: I officially don't get it

[Sas]

This weekend I dove a jacket BC for the first time since OW. I had the option to bring my BP/W but given it weighs 3kg+ I didn't want to carry around that extra weight (was using my backpack) and figured as I was only doing one dive I'd borrow a friend's spare jacket BC. Also I was curious to see how I'd go given my buoyancy/trim is miles better than it was in OW.

Basically I found that it was very easy to trim out (pics + videos confirm this ), I felt no squeeze unless I had it fully inflated (I didn't need much air in it at depth so not sure how it would be at depth) and on the surface I noticed *no* difference between it and my BP/W as far as ease of staying upright. The main difference I found that I really hated with the jacket was how unstable it is in the water. It was sliding around, turning and moving in the water would cause the tank to wobble and so on. Anyway, it further confirmed that for me, a BP/W suits me better but the jacket was not nearly as bad as I was expecting (given how I remember it from OW). Given my trim and buoyancy is ok now, it did not really affect that (whereas when I switched to the BP/W there was a marked improvement as I was still sorting that out and the BP/W assisted this). Anyway, ymmv but that was my experience going back to a jacket BC

 

[elan]

Trust me, Tobin aka Cool_hardware52 knows exactly what he's talking about. He is an industry expert as well as the maker of some damn fine technical diving gear. IF there was a need for a 100# wing, he would be selling them.

Yes , I can confirm that, he did calculations for my rig Worthington double HP100 and we ended up with 49lb wing which took into account possibility of carrying double HP120 can light etc. Now I think I barely inflate the wing to 30% when I'm full. I know 20lb is there for the dry suit failure. And some % as the margin. So I felt all his calculations worked out perfect. The wing does not wrap. If there is air trapped it's very little, all calculations match against my other 2 configs. I'm happy with his advice and the product.

 

[MSilvia]

Actually it was a legit question....... What would you need it for?

You could fill it with helium and float above the Macy's Thanksgiving parade.

Seriously though, unless you were doing a dive where you had a reasonable expectation of being 100lbs negatively buoyant at some point, there is no need to compensate for 100 lbs of negative buoyancy. In my opinion, there is a safer way to do everything I can think of that might make you that negative (for example, if you're trying to recover a 75 lb. anchor, use a lift bag), so as far as I can tell it's a solution to a problem that should never exist.

Of course, the day I have a drysuit failure while my feet are trapped in a 70 lb. giant clam, I'll take it all back.

 

[matt_w]

Even in this case it is just a matter of training. Learning how to saw your legs off without burning down your remaining gas is an essential skill which is rarely taught anymore. (If it ever was taught correctly).

You could fill it with helium and float above the Macy's Thanksgiving parade.

Seriously though, unless you were doing a dive where you had a reasonable expectation of being 100lbs negatively buoyant at some point, there is no need to compensate for 100 lbs of negative buoyancy. In my opinion, there is a safer way to do everything I can think of that might make you that negative (for example, if you're trying to recover a 75 lb. anchor, use a lift bag), so as far as I can tell it's a solution to a problem that should never exist.

Of course, the day I have a drysuit failure while my feet are trapped in a 70 lb. giant clam, I'll take it all back.

 

[wjknobles]

So... to add my .02.

To start off with I learned how to dive in a jacket-style BC, however the first BC I bought was a BP/W ... since then I have owned nothing else (Started with a Halcyon, now have 3 DSS). I prefer to dive BP/W and prefer to teach BP/W (both as what I am wearing and as what my students are learning).

However, I also work for a university scuba program ... and based on the gear available we teach in a jacket-style set-up. There are benefits to this ... it is similar to what most dive operations have to rent. There are also downsides ... it ROYALLY screws up buoyancy and trim for beginning divers.

It is possible to trim out and perfect buoyancy in a jacket-style BC, it just takes time and experience. I will always say that jacket-style BCs are not easy to learn buoyancy and trim in. This is generally due to the location of the lift and weight on the set-up. Your basic jacket-style BC has all lift centered around the lungs/upper torso and all weight on the hips. This immediately puts a diver into a head-up, feet-down position (i.e. not streamlined). With practice and experience divers can overcome this by distributing weight and tweaking body positioning. Beginning divers do not have this experience. I do not know how many times I have watched new divers dragging their fins in the bottom, hitting coral, or stirring up silt from a downward oriented fin kick. Additionally, to maintain a streamlined position with a jacket-style BC requires constant effort (be it conscious or not).

A BP/W set-up helps alleviate some of these issues and allows for better trim and buoyancy. Lift is still centered over the lungs/upper torso, however weight is now placed in this same area. This creates a stable platform. The benefit of BP/W is the inherent stability. Tie this in to the custom-fit that can be achieved with a Hogarthian harness and you now have a stable platform that does not move around your body.

Jacket-style BCs work around the "few sizes fits all" mentality, so not everyone will get a comfortable or secure fit. For me personally I have to wear either a medium or small jacket-style BC in order to get a fit that is somewhat secure (i.e. not swimming inside the BC). According to my body size I should be wearing a large.

I'll admit you need to dive what you are comfortable in. If you are comfortable in a jacket-style BC, then so be it ... you're comfortable, you're enjoying your dives ... life is good. I still ultimately think the BP/W set-up is more stable and a more flexible platform, and for these reasons dive a BP/W unless I am required to dive a different set-up. I also ideally teach all students (beginning with OW) in BP/W.