BP/W: I officially don't get it

[Cave Bum]

Did you factor in the weight of the backplate and all the other doohickeys that are part of the rig?

That thar' must be one o' them technical scuber terms, a?

 

[MSilvia]

In terms of achieving stable horizontal trim, I do not see why one (a rear inflate BC vs. a BP/W system) would be superior to another. This is a function of being properly weighted and proper placement of the weight. The rest of it is diver skill - just like a rider balances himself on a bicycle.

There is one significant difference that comes to mind, and that is that a BP/W inherently maintains a constant center of balance relative to the diver's body. Assuming a horizontal diver, the wing is above the lungs, and the plate, STA, and tank are all right there too, so all changes in gas volume/buoyancy apply force to the same point on the diver's body, which makes 'dialing in' trim easier. Sure, you can do that with a different kind of BC by using trim pockets, ankle weights, etc, but with a BP/W, you shouldn't need to.

 

[Adobo]

That thar' must be one o' them technical scuber terms, a?

I am edumacated.

 

[Adobo]

There is one significant difference that comes to mind, and that is that a BP/W inherently maintains a constant center of balance relative to the diver's body. Assuming a horizontal diver, the wing is above the lungs, and the plate, STA, and tank are all right there too, so all changes in gas volume/buoyancy apply force to the same point on the diver's body, which makes 'dialing in' trim easier. Sure, you can do that with a different kind of BC by using trim pockets, ankle weights, etc, but with a BP/W, you shouldn't need to.

I bet you could pick up a scubapro knighthawk and in 2 or 3 dives, have it dialed in for correct weighting and trim. Maybe it is easier to do this in a backplate but by how much, I am not sure.

Again, I think where the substantial differences are between these two systems has more to do with the ability to add on the the backplate platform.. going to doubles, canister light, scooter, stage bottles, reel, etc are easily done with a backplate system. With a Knighthawk, you start to have headaches as soon as you want to do any of the stuff I just mentioned.

 

[elan]

There is one significant difference that comes to mind, and that is that a BP/W inherently maintains a constant center of balance relative to the diver's body. Assuming a horizontal diver, the wing is above the lungs, and the plate, STA, and tank are all right there too, so all changes in gas volume/buoyancy apply force to the same point on the diver's body, which makes 'dialing in' trim easier. Sure, you can do that with a different kind of BC by using trim pockets, ankle weights, etc, but with a BP/W, you shouldn't need to.

You have mentioned that before I wanted to do it Yes this is the same thing I can see. The wing is pulling the weight of the tanks with GAS up from both sides. Pretty stable position. With jacket style the BC would push the the weight up which is less stable. An analogy would be the same as a ball is laying in the groove is in much more stable position than a ball on the top of the hill.

 

[elan]

Did you factor in the weight of the backplate and all the other doohickeys that are part of the rig? My steel plate with STA, stainless steel buckles, cambands with stainless steel buckles weighed in at over 11lbs. Whether the weight is on your weight belt or on your rig, it is still weight.

BP/W does not generally have all that padding that most BC (even rear inflation) have. My BC has a lot of crap that suppose to make it stronger and lightweight w/o using a plate on the back. in fact it is buoyant and still very loose. I need at least 3 lb to make it sink. Say I dive BP with 8 lb on the belt and 18lb with BC with the same tank. BP is 6lb so the real difference is 4lb! Some of it is wing but most of it is the padding I have on the back.

 

[MSilvia]

I bet you could pick up a scubapro knighthawk and in 2 or 3 dives, have it dialed in for correct weighting and trim. Maybe it is easier to do this in a backplate but by how much, I am not sure.

Again, I think where the substantial differences are between these two systems has more to do with the ability to add on the the backplate platform.. going to doubles, canister light, scooter, stage bottles, reel, etc are easily done with a backplate system. With a Knighthawk, you start to have headaches as soon as you want to do any of the stuff I just mentioned.

I agree. I think it's somewhat easier in a BP/W, but it shouldn't be a big deal either way. If you expect to put on a BP/W for the first time and see magical improvements in your diving, you're likely to be disappointed by the hype you bought. If you want to be able to configure your gear any way you want and maybe take some weight off your belt/pockets, a BP/W is a good way to go, and the ease of trimming it is nice frosting on the cake.

 

[TSandM]

To adobo's list of benefits, I would add the stability of the tank on your back. Soft BCs just don't give the same sensation of tank, BC and diver being a seamless whole.

 

[halocline]

To adobo's list of benefits, I would add the stability of the tank on your back. Soft BCs just don't give the same sensation of tank, BC and diver being a seamless whole.

Exactly, and even though you can put trim weights on the cambands, it's not as good as having the ballast evenly spread out against your back. That's ideal weight distribution, especially with an AL tank, and I can definitely tell the difference between using my steel plate as opposed my AL plate with camband weights. The soft harness BCs simply don't couple the tank to your back in the same way. Think about it, you have a round hard surface (the tank) on a soft flat one (your back in a wetsuit). By strapping the tank onto a rigid flat surface, it spreads out the points of contact over a large area of your back. That's one reason you can have so much stability even with a minimal and somewhat loose-fitting harness.

 

[Adobo]

To adobo's list of benefits, I would add the stability of the tank on your back. Soft BCs just don't give the same sensation of tank, BC and diver being a seamless whole.

Actually, this is a good point. I was just reminded by a friend that not only can you tightly couple all of the components on a BP (tanks to the rig), you can also tightly couple the rig to the diver (with the use of a crotch strap).

How much of either you can achieve in a rear inflate BC, I don't know. I do know that I have seen Scubapro models and Zeagle models that did not come with dual tank bands or crotch straps out of the box.