Plans of Alex Deas

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Alex Deas sent me these plans for

Backplate
Keelweight
Single Cylinder Adaptor Plate
Tankbands

His comment:
"Please make whatever non-commercial use of these designs as you wish. They have improved my diving comfort, and safety out of the water with heavy tanks." (23.1.99)

Alex's Backplate

The Backplate is designed to make handling big twins much easier and consequently is quite different from normal backplates. It's objective is to transfer the weight to the hips.
To do this it:

Uses a harness with a wide waistband, such as a ScubaPro TEK harness, or a Transpak, and mounts the harness lower down.
The backplate is much longer than usual: the bottom of the plate is only just above the bottom of the cylinder. This means the plate transfers weight into your posterior.
The plate is flat across the chest, but curved to follow the spine at the bottom. This contrasts to a normal plate which curves into the shoulders and this is very bad anatomically.
The material is 4mm Aluminium. This will deform slightly when fully loaded. The alternative material is 3.2mm Stainless Steel grade 316 or 320, but this will not deform.

ZIP File mit Acad DWG Format | DXF Format (13) | WMF Format | und GIF File

Keel Weights

There are lots of problems with normal weight systems.
These are:

They can be dumped, by accident or folly. The fact is you should never need to dump weights because as you start to rise, all residual air expands in your dry suit or your wet suit decompresses, causing you to rise faster. I cannot find a single accident report from a properly weighted diver not being able to dump weight, but I see plenty from weights being dumped accidentally.
The weights are around your waist, and tend to slip as the suit fills and deflates.
The buckle interferes with mounting your BCD buckle where it belongs (on your hip).
The weights on you, with wing behind, push you face into the water. It can be very hard getting on your back to swim if you use a technical BC.

The keel weights overcome all these problems.
Particularly:

The mount via the cam bands or cylinder bands on your tanks. This pushes you onto your back into a mouth-out-of-water position on the surface.
The weights cannot be released and do not slip. A pair is designed to hold 23lb, but can hold almost 40lb. I use one on each tank to avoid tilting on one side. By the way, if you use more than 23lb in total you are probably overweighted: I can get down fine using 23lb with a dry suit, or a 8mm wet suit, with a single tank and no backplate or ankle weights. With twin tanks, I can get down with 16lb in the same rigs.
There is no buckle, so your BCD buckle can now be where it need to be, on your hip like a mountaineering rucksack.

By the way, the keel weight tube also acts as a battery compartment for a Dive Light: it is important to fit the O ring as indicated.

The end-cap screws on using an Allen key in the hole.

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Tank Bands

These mount the tanks closer than normal so you can use a readily obtained 80l manifolds on 120l tanks.

Change one number on the diagram, and the bands can work with any cylinder size.

Compared with normal bands, they keep the tanks closer, to act as one item not two, considerably reducing drag. They also avoid a bolt sticking up which can catch on nets etc underwater.

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Retaining or Adaptor Plate for single cylinders

This mounts a single cylinder on a technical harness using cam bands, or reversing the plate, the twinning bands attach to the plate, and the plate attaches to the wing and harness through the standard bolt holes in the wing. This is necessary if you want to strap the tanks lower than normal: a good idea because some harnesses have a cam band almost around the neck of a cylinder at the right height.

Another reason for mounting cylinders lower is if you have a manifold protector, to save the protector from wacking your head as you look up.

ZIP File mit Acad DWG Format | DXF Format (13) | WMF Format | und GIF File