Aqualung backplate, how to connect crotch strap?

[johnn]

I was given a circa '60 Aqua-lung backplate (along with a LP72 tank).   The backplate is plastic (if that helps_

The backplate and straps cleaned up nicely, but I'm confused about how to connect the crotch strap so it the backplate doesn't ride up.

Is something missing from the bits I have?

Apologies, I don't know how to insert an image I'd be happy to email one

[james1979]

John,

Here's a post Phil did on using Imgur (I use it for here as well):
vintagescuba.proboards.com/thread/5473/using-imgur-post-photos

This sites storage for natively hosted images apparently ran out years ago.

I'd have to see the plate in question to venture an opinion.

Respectfully,

Jammes

[vance]

There's single thickness plates and blow-plastic backpacks. They are very different, and we need to know what you are asking about. Both can be adapted to DH.

Cheers,
Phil

[SeaRat]

Here is a page from the 1972 USD catalog.

USD Backpacks001 by John Ratliff, on Flickr

I have a feeling you are talking about the Dolphin-Pac inthe lower left. Is that correct?

John

[johnn]

"Dolphin-Pac". Kinda. Mine has plastic shoulder straps that connect to the backplate. Those shoulder straps then have buckles to attach the webbing Mine has a slot for a crotch strap and even came with one threaded into the backplate

[SeaRat]

There should be a metal threader ring that will allow you to form a loop in the crotch strap. That loop goes into the waist strap; the waist strap fits through the loop.

These have a double D-ring that is used to quick release by threading the end back through the bottom D-ring. I’ll try for an illustration later. But the waist strap and the two shoulder straps (below the plastic strap) should be threaded for a quick release.

I have used that Dolphin-Pac and the shoulder straps are really slippery on a nylon/fabric wetsuit. Be aware of that, as it is a bit irritating.

John

PS, it will be after Memorial Day before I can get an image out for the double D-ring quick release. So let me describe it. On the shoulder, the double D-rings hang down. The bottom shoulder strap has to come up through those two D-rings, come out and be routed into the lower one. This can be cinched down to its desired length. Then, the dangling end is threaded back up through the lower D-ring, with enough of the strap out so that it can be pulled in an emergency. If it is pulled, the loop will go up into the D-rings, and release the entire strap, which comes loose through the hole behind the outside edge of the D-rings.

PS2, I found a photo of my gear which may help. Look at the right shoulder strap on the ground. It shows the routing of the lower strap through the D-rings.

IMG_1423 by John Ratliff, on Flickr

This photo I took under a reef at Okinawa in 1968 shows Terry Wetzel and Stephen Samo, two USAF Pararescuemen, on a dive using the USD harness. It also shows the quick release on both Terry’s chest strap and his right shoulder strap.

PJ Okinawa Dive003 by John Ratliff, on Flickr

[mackintoshman]

vintagescuba.proboards.com/thread/6153/aqualung-backplate-connect-crotch-strap

[mackintoshman]

bac pac 2 by william mackintoshman, on Flickr

[mackintoshman]

slide the stap thru the back of the PAC and adjust, then tighten the PAC. That will hold it in place.

[mackintoshman]

bac pac 1 by william mackintoshman, on Flickr

[johnn]

That's it!!

Thank you very much. All I'm missing is a tri-glide of the appropriate width for the crotch strap

[vance]

That backpack is a dog-bone, if I'm not mistaken. WTH is tri-glide?

[surflung]

Nope... That's not the Dog Bone...
- This image was clipped from a 1963 US Divers Catalog that I downloaded from the VDH site.


The Dog Bone is on the left... It takes the Dog Bone nick name from it's unique shape. Interesting how it has a recess on top for correct positioning of a double hose regulator. Kind of like the VDH plate.

[vance]

Thanks for the correction! I was wondering where the name came from. It's pretty obvious from the photo....

[SeaRat]

Sept 8, 2023 10:47:12 GMT -8 mackintoshman said:

bac pac 1 by william mackintoshman, on Flickr

Note that neather the shoulder straps nor the waist strap are connected in a quick release, which is what they were designed for. The end of the strap needs to go back up through the outside D-ring to make it a quick release.

John