Differences between Jacket, Back-Inflate, BP/W

[Ioncloud9]

So why would I choose SS over Aluminum BP?

 

[tbone1004]

So why would I choose SS over Aluminum BP?

if you need lead, then you choose SS because it gives you ballast advantages. You choose Aluminum/Kydex etc if you don't need the ballast which is typically only in rebreathers and doubles though can also exist with steel tanks without a wetsuit

 

[Lorenzoid]

So why would I choose SS over Aluminum BP?

Choose SS over aluminum (or kydex) if you want 3-4 lbs. of your total ballast to be integrated into your backplate instead of in the form of lead weights. If you don't need that 3-4 lbs. to weight yourself properly because, say, you are diving heavy steel tanks, then by all means feel free to choose aluminum.

As for backplate versus weight belt, there may be some advantage to having the weight closer to your lungs (center of buoyancy) rather than on your hips. And some people simply don't care for weight belts. For instance, when I dive with a thin wetsuit and Al 80 tank, a steel plate provides all the ballast I need to weight myself properly--no weight belt required. Although it seems reasonable to choose an aluminum or kydex plate for trips involving air travel, I am willing to tolerate the few pounds of additional weight in my luggage and take the steel plate with me to tropical destinations.

 

[RyanT]

just to follow up on what tbone said, a SS backplate is around 6 lbs negative. An aluminum is around 2 lbs. negative. So you'll get roughly 4 more pounds of weight with SS.

 

[Ioncloud9]

What about lift? I'm not really planning on a lot of cold water diving. The mid 60s is about as cold as I'll go.

 

[divad]

I switched from a SS bp to an AL bp so I could move 4 lbs to my waist where I needed it.

 

[2airishuman]

But what are the other major differences and how is it different when wearing one through all the stages of diving?

Be careful reading the replies because there is a systemic bias towards BP/Ws at ScubaBoard. I dive a BP/W so I'm probably part of the problem, but I haven't drunk quite as much electric koolaid as some people.

Some advantages of jacket-style BCs (including back-inflate ones)

1. Widely available for purchase or rental.
2. All instructors and divemasters are familiar with them.
3. Divemasters will generally set up your gear for you without your assistance, while with a BP/W they will do so only with your close supervision.
4. Beyond selecting a BC of proper size and some minor adjustments, there is generally no need to assemble the new BC or to configure the BC to fit you. (Initial fitting and adjustment of a BP/W if you've never used one before takes an hour or two topside and then a dive or two to get everything just the way you want it)
5. There are pockets, so you generally will not need to accessorize the BC so you can find a place for your stuff, nor will you generally need to add bolt snaps to your stuff so you can clip it off.
6. The weight integration is easy to use and distributes the weight between your shoulders and hips. (Most BP/W divers use a weight belt, or no ditchable weight at all, although there are weight pockets available as an accessory)
7. No crotch strap (Some divers find the idea of a crotch strap distasteful because they are concerned that it might sexualize their appearance or the tactile experience of the dive).
8. Generally easier to don and doff for people with limited shoulder or arm mobility, especially in the water. (Although this can be achieved with a BP/W by adding a release to one of the shoulder straps)
9. Typically more comfortable at the surface, especially with buoyant tanks (particularly with an empty aluminum cylinder in salt water), although this is controversial as some dedicated BP/W enthusiasts claim it is simply a matter of proper technique and weighting.
10. Less susceptible to pinch flats. (Wings in a BP/W configuration can be damaged if pinched between the backplate and a hard object. Not a problem during a dive but can happen when the BC is being transported or handled topside. Best practice with BP/W is to remove the wing from the backplate when it is not in use, but not everyone does this because of the extra time required for disassembly and reassembly)

Some advantages of BP/W BCs

1. Readily able to support multiple cylinders, particularly twinsets and stage/deco cylinders. (Although some jacket-style BCs can accept a twinset and most of them can accept a small stage cylinder)
2. Can switch out buoyancy cells (wings) to match the needs of the dive, without carrying multiple BCs.
3. Generally more durable and easier to repair and maintain. Major wear items (webbing) can be easily replaced with no (or minimal) sewing. Power inflator, hose, and elbow is generally universal fit. Rings, slides, and buckles are generally metal and therefore much less susceptible to damage.
4. Typically less unwanted buoyancy when empty, because there is less fabric and less trapped air.
5. The backplate itself is typically negative, which in most situations is an advantage.
6. Although one or two vendors make backplates in multiple sizes, in general, backplates will fit anyone with only webbing changes.
7. Less clutter in front and sides, improving arm mobility and leaving more space for cameras and spearguns.
8. For busty women, less pressure on the breasts.
9. Fewer problems with the BC riding up, and less pressure on the waist and abdomen, due to the use of a crotch strap. (Though a crotch strap can usually be added to a jacket BC)
10. Better able to support a long hose configuration, since a jacket BC doesn't have a belt where the loop can be tucked in.
11. Typically make it easier to maintain good horizontal trim (although with proper weighting and technique it is certainly possible to maintain good horizontal trim with a jacket BC)

For most divers, this is all really minor stuff. You can be happy with a good quality, properly fitting jacket BC, as long as you're not diving twins or a stage. You can be happy with a BP/W, as long as you're willing to take the time to set it up and learn to get in and out of it in the water.

 

[tbone1004]

What about lift? I'm not really planning on a lot of cold water diving. The mid 60s is about as cold as I'll go.

lift is dependent on tank size and wetsuit thickness. 30lb is a good rough size for most. I'm partial to the Deep Sea Supply wings because they are very narrow. Not really the wing you want if you regularly dive say HP80's or AL50's/63's, but perfect for HP100's or AL80's.
The three wings in that range are the Torus 26, LCD30, and Torus 35. Torus 35 is great for those with a lot of lead on the waist belt because it has a lot of lift towards the bottom, and the other two are more balanced.

 

[2airishuman]

What about lift? I'm not really planning on a lot of cold water diving. The mid 60s is about as cold as I'll go.

Most people use a 30# wing for singles. Most jacket BCs have at least that much lift. Either one is plenty for any single-cylinder dive, unless you're badly overweighted..

 

[Lorenzoid]

. . .

1. Divemasters will generally set up your gear for you without your assistance, while with a BP/W they will do so only with your close supervision.

Or sometimes they will bravely go ahead and set it up for you, but do it incorrectly. Sometimes, when I travel to parts of the world where BP/Ws are rare, I secretly wish I had a traditional BC so I could consistently take advantage of that level of service.

To add one more thing to your comprehensive list, for air travel a BP/W generally packs more compactly than a bulky traditional BC. If I remove the cam bands from the plate, it lies almost flat in the bottom of my bag. The wing lies flat, too. This, along with the ability to choose aluminum or kydex over steel for travel weight savings, is why in all those threads entitled something like "What travel BC should I buy?" the second or third reply advises to buy a plain old BP/W rather than a jacket or back-inflate marketed as a "travel BC."