BP/W: I officially don't get it

[dumpsterDiver]

If you are having trouble at the surface in a BP&W you don't have it properly set up, and or you are not properly weighted.

Ya, it's really that simple.

Tobin

I usually use single big LP steel tanks 108, 125 etc. I can float fine on the surface with my BP/W, however trying to "lean back" for 15 or 20 minutes while the boat searches for you is certainly not what I consider "optimum" and after literally thousands of hours in the water, I think I am qualified to make an informed opinion on how the two different types of BC's perform on the surface and which is more comfortable while floating in rough seas.

As for my weighting, I generally wear zero to 7 lbs of lead in the summer and 12 or so in the winter with a 2 piece 5 mm suit on.

I bought a BP/W, and i tried it for over 2 years. It works OK, it seems to hold me a little more horizontal underwater, but there are other drawbacks, that make me reach for the old BC when diving w/o a stage bottle in warm water.

 

[cool_hardware52]

I usually use single big LP steel tanks 108, 125 etc. I can float fine on the surface with my BP/W

Most people can

As for my weighting, I generally wear zero to 7 lbs of lead in the summer and 12 or so in the winter with a 2 piece 5 mm suit on.

That tells me nothing about whether or not you are properly weighted.

Tobin

 

[halocline]

If you want to choose dive gear based on how it floats you on the surface, fine. I'd rather choose it based on how it actually works while diving. It is dive gear, not float gear.

 

[dumpsterDiver]

Most people can



That tells me nothing about whether or not you are properly weighted.

Tobin

Well if I am wearing ZERO lead, I would think that you might realize that my options for ballast placement are rather limited.:blinking::blinking:

 

[dumpsterDiver]

If you want to choose dive gear based on how it floats you on the surface, fine. I'd rather choose it based on how it actually works while diving. It is dive gear, not float gear.

My point is that for some people, both aspects are relevant. Plus, some of this is splitting hairs. It is not that BP/W is bad and the BC is great, it is more that the difference may not be so large, particularly when you get a BC configured similarly to a BP/W...It seems that my preference right now is for the Bc, that's all.

I read all the hype about BP/W on this board, bought one and honestly never experienced any dramatic improvement over my old BC.

 

[cool_hardware52]

Well if I am wearing ZERO lead, I would think that you might realize that my options for ballast placement are rather limited.:blinking::blinking:

If you do have a point you are doing a good job of concealing it.

Weighting involves your total ballast, i.e. all those things that do not float like your plate, reg, cylinder (if negative when empty) lights etc.

A statement like "I wear zero lead" is meaningless in isolation.

Tobin

 

[shoturtle]

Oh goosh, here we go again.

 

[FishOutUvH2O]

If you do have a point you are doing a good job of concealing it.

Weighting involves your total ballast, i.e. all those things that do not float like your plate, reg, cylinder (if negative when empty) lights etc.

A statement like "I wear zero lead" is meaningless in isolation.

Tobin

Crap! Now I just got confused. Are you asking him about weight distribution on the rig? Or are you asking about weight as it pertains to buoyancy?

 

[cool_hardware52]

Crap! Now I just got confused. Are you asking him about weight distribution on the rig? Or are you asking about weight as it pertains to buoyancy?

Dumpy claims that BP&W's essentially **Have** to force the diver forward at the surface, i.e. one diver based on his personal experience, knows for a fact that BP&W's are suboptimal at the surface, and this cannot be corrected with setup or proper weighting.


My experience,OTOH designing, building, and fitting countless new BP&W users has been exactly the opposite. If the gear is correctly set up, and if the diver is properly weighted a BP&W is perfectly comfortable at the surface.

Being correctly weighted, as in total weighting, is very important. Why? if the diver is overweighted they need to put a lot of gas in their wing, a wing that's full down to your hips can push you forward.

OTOH if the diver is properly weighted they need only a small "puff" of gas in the wing. This gas will be behind the divers head and shoulders only and as such cannot push the diver forward.

Weight distribution can help, but correct total weighting and proper harness adjustment, particularly the crotch strap are important.

I know that I can make a diver miserable in a BP&W with a loose crotch strap and too much weight, and in 5 minutes I can make them happy campers with a harness adjustment and proper weight check.

The choice is yours who to believe.

Tobin

 

[peterbj7]

Can I explore the physics a little? If your tank is a massive steel one and you have little other weight there's a good chance that when floating at the surface you'll actually be upright. Otherwise, if you have all of your buoyancy provided by a large bag of air behind you, and all your weight (lead and otherwise) is somewhere forward of that, there is inevitably a force couple that tips you forwards. This can be minimised by careful design/fitting but it cannot be removed.

Clearly the further back your weight the less marked this effect, so if you have a massive SS backplate and little other weight then the effect will be small, but it'll still be there. For reasons of safety a diver might prefer to have a greater proportion of his weight to be ditchable, which will be forwards and hence tend to exacerbate the force couple. If you're doing seriously cold water diving it's probable that you'll actually have a lot of other weight, and wherever that's positioned it'll be forwards of the buoyancy bag.

I know that except when diving with a SS backplate in warm water when typically I am carrying no lead at all, there is a tendency to pitch me forwards/ face down at the surface. I can (and do) minimise that effect but it is always there.

Is there something wrong with my analysis of the physics? Anything I've missed?