Backplates vs Soft diving harness

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seasick

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Hi all, just would like to start a discussion on the stability of using the above captioned for diving twins.

IMHO, when twins are attached to a backplate, you basically have 2 air-tanks bolted to the backplate's centre channel. On some designs, the sides of the backplate does not come in contact with both air-tanks. The backplate sides are only in contact with the diver's back. When a diver is horizontal in perfect trim, this results in the air-tanks being lifted off the diver's back, forcing a balancing act as the air-tanks are only being supported by the centre channel via the tank bands.

In contrast, when a diving harness(eg. DiveRite Transpac, Oxycheq A-pac, OMS IQ pack) is attached to twin tanks for diving, both tanks are in direct contact with or resting on the diver's back on both sides all the time.(This will only occur when both shoulder straps, waist band and crotch are tightened and adjusted properly) Now wouldn't it seem that a diving harness is more stable?

It's like riding on a motorcycle(backplates) vs driving a car(Diving harness) & I think that there's no doubt that a car has better stability & balance over the motorcycle.

My way of thinking may be going against the widely accepted views that a backplate is more stable over a harness. But I would like to see if there's anyone out there that share the same view as me.
 
seasick:
On some designs, the sides of the backplate does not come in contact with both air-tanks.

Can you give me an example of such backplate design? :huh: I have dived a few different backplates with my AL80 doubles and I haven't seen one in which the center channel of the backplate will actually touches the tank bands without the plates touching the tanks. In fact, the sides of the plate will actually touch the tanks and the center channel isn't even close to touching the tank bands.

seasick:
In contrast, when a diving harness(eg. DiveRite Transpac, Oxycheq A-pac, OMS IQ pack) is attached to twin tanks for diving, both tanks are in direct contact with or resting on the diver's back on both sides all the time.(This will only occur when both shoulder straps, waist band and crotch are tightened and adjusted properly) Now wouldn't it seem that a diving harness is more stable?

It's like riding on a motorcycle(backplates) vs driving a car(Diving harness) & I think that there's no doubt that a car has better stability & balance over the motorcycle.

My way of thinking may be going against the widely accepted views that a backplate is more stable over a harness. But I would like to see if there's anyone out there that share the same view as me.

Never dive with a soft harness myself but I know someone who did. He has switched to backplate for his doubles and according to him, backplate+wing setup if way more stable.
 
wunat:
Can you give me an example of such backplate design? :huh: I have dived a few different backplates with my AL80 doubles and I haven't seen one in which the center channel of the backplate will actually touches the tank bands without the plates touching the tanks. In fact, the sides of the plate will actually touch the tanks and the center channel isn't even close to touching the tank bands.

One is from an old Halcyon design(according to the owner)
Some do not have brands like DiveRite, OMS etc......

We mostly use 7.25" tanks.
 
seasick:
wunat:
Can you give me an example of such backplate design? :huh: I have dived a few different backplates with my AL80 doubles and I haven't seen one in which the center channel of the backplate will actually touches the tank bands without the plates touching the tanks. In fact, the sides of the plate will actually touch the tanks and the center channel isn't even close to touching the tank bands.

One is from an old Halcyon design(according to the owner)
Some do not have brands like DiveRite, OMS etc......

We mostly use 7.25" tanks.

My guess is you have odd tank bands. In my experience it would be an odd combination of backplate and tank bands that would allow the backplate center channel to bottom out on the tank bands before the tanks contact the plate.

There are some steeply bent plates with deep center channels, FredT's come to mind. I've never seen even a FredT plate bottom on the tank bands.

Do you know what bands are being used?


Tobin
 
cool_hardware52:
There are some steeply bent plates with deep center channels, FredT's come to mind. I've never seen even a FredT plate bottom on the tank bands.
I use my FredT with LP85's (7.25"). The plate contacts the tanks (with the wing in between plate & tanks, of course) well before the wingnut would bottom on the (OMS) bands. I've also rigged it to E7-120's with Highland Mills bands and there's plenty of bolt left when the plate gets to the tanks.
Rick
 
Rick Murchison:
I use my FredT with LP85's (7.25"). The plate contacts the tanks (with the wing in between plate & tanks, of course) well before the wingnut would bottom on the (OMS) bands. I've also rigged it to E7-120's with Highland Mills bands and there's plenty of bolt left when the plate gets to the tanks.
Rick

That's been my experience also.

IIRC Highland Millwork was selling a backplate designed to bottom on the bands, maybe not anymore....


Tobin
 
seasick:
Hi all, just would like to start a discussion on the stability of using the above captioned for diving twins.

IMHO, when twins are attached to a backplate, you basically have 2 air-tanks bolted to the backplate's centre channel. On some designs, the sides of the backplate does not come in contact with both air-tanks. The backplate sides are only in contact with the diver's back. When a diver is horizontal in perfect trim, this results in the air-tanks being lifted off the diver's back, forcing a balancing act as the air-tanks are only being supported by the centre channel via the tank bands.

In contrast, when a diving harness(eg. DiveRite Transpac, Oxycheq A-pac, OMS IQ pack) is attached to twin tanks for diving, both tanks are in direct contact with or resting on the diver's back on both sides all the time.(This will only occur when both shoulder straps, waist band and crotch are tightened and adjusted properly) Now wouldn't it seem that a diving harness is more stable?

It's like riding on a motorcycle(backplates) vs driving a car(Diving harness) & I think that there's no doubt that a car has better stability & balance over the motorcycle.

My way of thinking may be going against the widely accepted views that a backplate is more stable over a harness. But I would like to see if there's anyone out there that share the same view as me.

I have sold, assembled, seen, and used almost every type of backplate on the market (probably missed a few, but not many) and I have never seen the situation you describe. In fact, I don't know if it is even possible, unless you have some really strange homemade backplate or bands.

That being said, I also have a large number of doubles ocean dives on the Dive Rite Transpac. There is a great deal of talk about the Transpac not being "stable" with doubles. I did not find that. I thought the softpack was just as stable as a backplate. In addition, it doesn't pinch my "lovehandles" at all, unlike several backplates I have used. I think, to each his or her own. Thanks.

Phil Ellis
 
Phil,

Have you ever tried to squeeze 7.25" bands on 8" tanks? Where would the bands fall in relation to the backplate...

-P
 
I had this very discussion the other day with the owner of DiveRiteExpress, Mark.

Mark states that a properly sized and adjusted TransPac is just as good with doubles as a plate. Since he is, in my humble opinion, an expert on the subject, I trust him when he says this.
 
seasick:
IMHO, when twins are attached to a backplate, you basically have 2 air-tanks bolted to the backplate's centre channel. On some designs, the sides of the backplate does not come in contact with both air-tanks. The backplate sides are only in contact with the diver's back. When a diver is horizontal in perfect trim, this results in the air-tanks being lifted off the diver's back, forcing a balancing act as the air-tanks are only being supported by the centre channel via the tank bands.

In contrast, when a diving harness(eg. DiveRite Transpac, Oxycheq A-pac, OMS IQ pack) is attached to twin tanks for diving, both tanks are in direct contact with or resting on the diver's back on both sides all the time.(This will only occur when both shoulder straps, waist band and crotch are tightened and adjusted properly) Now wouldn't it seem that a diving harness is more stable?

Well, I have certainly not found that to be true. I'm sure there are some backplates somewhere that do this, but they are probably the execption rather than the rule. On every BP I have seen the sides of the plate DO touch both tanks. I have 2 Halcyon BP, and they both touch the tanks are are rock solid. On the other hand, the harnesses you talk about are made of fabric, and while I am not saying that they are not sturdy and well-built, there is only so much stability that nylon and fabric can provide. That has been my experience anyway, ymmv.
 

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