A BC is a central piece of your life support system. A wing type BC is a back mounted BC made of an inner bladder, external protective shell, inflator, dump valve, and corrugated hose. The external shell protects the bladder from abrasion or puncturing. The wing BC can be used with double of single tanks and comes in lift capacity sizes ranging from 35 to 100 pounds. Most technical divers use BCs with about 50 lbs of lift. Excessive lift increases the size of a BC and creates more drag. Some manufacturers offer high lift capacity BCs with a bungee cord retaining system designed to reduce the drag of the BC. Some wreck divers and deep ocean divers use two sets of wings or a dual bladder system, but cave divers generally use a single bladder or wing system. If you decide to use two separate wings or a dual bladder system, do not connect the second inflator system. Power inflators can jam open and cause the wing to inflate uncontrollably causing a rapid ascent.
When shopping for a wing BC, look for quality construction, durability, and the correct size you need. Some manufacturers use very long corrugated hoses, which make it more difficult to dump air and is more vulnerable to entanglement.
Cost: $250 to $500
Backplate and harness
The backplate and harness mount to your single or dual tank system and are used to carry the tanks on your back. Backplates are made of aluminum, stainless steel, or ABS plastic. Softpac systems also exist and use a padded backpack system. The harness is typically made of webbing material. Some harness systems are simple single-piece webbing harnesses, while others are two-piece designs with padded straps, etc. All most all harness systems come standard with D-ring attachments for you shoulder straps and waist belt.
A backplate and harness system is designed to fit well, be flexible, and provide a low profile in the water. If you plan on using a harness system with thick wetsuits, dry suits, and thin wetsuits, sizing is very important as each exposure suit style requires more or less webbing to fit properly. You don’t want to cut off too much webbing when sizing so that you can’t where your system with various exposure suits. Many technical divers have two or more backplates and harnesses for use with different suits and configurations.
The buckles, D-rings, and other hardware that comes with a backplate and harness should be stainless steel, which is more durable against the elements. Some manufacturers use plastic buckles which aren’t as durable and don’t provide as good of hold on the webbing strap.
Cost: $100 to $200