Wed Feb 12, 2014 8:45 am
Welcome to the board and DH diving.
Off hand I am not familiar with the Halcyon plates so I am swaging it some but here goes. Looking at the Halcyon plate photos it appears to have a substantial ridge along the spine. If I am looking at the BP correctly, that ridge is going to lift the tank up off your back by an inch or more, that will hurt any DH regs performance a good bit. The next issue is a DH reg should be worn a good bit lower on the back than most people dive single hose regs. The "cans" (metal or plastic main body of the reg) needs to be roughly between your shoulder blades. In my experience, this positioning is difficult to achieve with most modern BCs or plates. The plates want to come to rest much higher than is acceptable even if the straps are adjusted so the top of the plate is in the correct position. If you manage to get the plate low enough, that tends to put the waist strap much too low. When "modern" DH diving, I use a Zeagle ET which is soft BP. In it's factory design, I could get the plate low enough but when I did, my waist strap ended up below my crotch....that did not work and was down right uncomfortable with a crotch strap...which you should use to prevent a BP from riding up. I had it modified to move the waist strap up several inches which put the waist strap where is should be and it now works great..
Then next issue you may have is the top of the plate making contact with the reg cans. That is not good on the cans if for no other reason than it scratches them. Most hard BPs just do not allow the cans to set low enough without hitting them. If you look at Bryans BP, it has the top of the plate cut out to make room for the cans.
So what do you need to look for. First off, find a BP that will keep the tank as close as possible to your back. Any ridge that holds the tank away from your back is not desirable. Some older BP do have ridges along the sides that the tank nest into, that is not a problem, they do not raise the tank but do tend to kept it in line. Tanks stays are a big no no unless they just guide the tank without lifting it off your back. Next make sure the straps can be adjusted so that the BP is low enough that when a tank and reg are mounted in it and placed on your back, the cans set between your shoulder blades AND when adjusted that way, the waist strap is not too low. By the way, your tank WILL feel way to low when walking.
The bottom line is , you can use your current BP but you will suffer a considerable loss of performance in any DH reg. The reg will work and provide you gas but it will not perform anywhere near optimally. If you wish to dive your Kraken as a modern reg, my best suggestion is to get one of Bryans BP’s , they are especially made to work with DH regs and will work fine with any single hose reg as well. If you prefer a more traditional route then look into one of the thin BP’s from the DH era like the Voit Snugpack, the USD Kam-EZ or one of Allan’s harnesses.
If you do a search on the board, you will find a lot of info on diving with DH regs and the BPs to use with them that myself and others have posted over the years. Ask away with your questions, I suspect there will be a lot of folks wondering the same things as the Kraken begins to show up at dive sites.
Herman