Understanding your Extended Range equipment

by   Profile Cat   When 6th February 2019

Choosing the right equipment for Extended Range diving is an essential element to ensuring enjoyable, safe diving experiences. All divers should use high quality, reliable equipment and have the knowledge about how to use it properly.

Very recently, the Maldivian Coast Guards began their SSI Extended Range Diver training. It was vital that they had a high level of understanding of how the selection and configuration of equipment can affect the diver’s ability and performance in the water, as it will be these Coast Guards who will be taking responsibility for such diving activities in the future.

Case Study – The Mares XR Harness
In this blog we will examine the configuration of the Mares XR harness along with the implications of incorrect assembly.

This article is by no means intended to be used as a replacement for training, but rather to provide the basic introduction of concepts applied to configuring a harness.

Whether you are purchasing a backplate and harness, renting or borrowing, having the understanding and the skills necessary to configure the equipment correctly is critical. The backplate and harness configuration will have a direct effect on your trim position in the water and your ability to reach your cylinder valves.

One of the greatest features of the backplate and harness set up is its ability to be configured for any body shape and size. It is streamlined, durable, adaptable, minimalist, robust and highly configurable. If the backplate and harness is incorrectly configured, not only will it be uncomfortable, but it could also pose a danger to your life, as you will not be able to achieve some critical skills with ease.

The Mares XR harness comes with the following individual pieces:

3.5m Webbing with center hole and grommet
3 x 40mm Elastic loop retainers

2 x bent D-rings
2 x straight D-rings
4 x 3-bar slides
2 x 3-bar toothed slides
1 x waist buckle

Crotch Strap
1.5m crotch strap
2 x straight D-ring
1 x 3-bar Slides

Shoulder Straps
The continuous one-piece webbing is the preferred choice for many Extended Range divers as it minimises the risks of breaking as it is very robust. When threaded to the backplate, the shoulder straps should be tight enough so that when you are wearing the harness you can reach back and touch the top of the backplate with your fingers. The straps, however, should be loose enough that you can still easily slip at least 2 or 3 fingers underneath the shoulder strap. This means that the harness can also be put on and taken off with relative ease either on land or on the surface. If the straps are too loose, the plate will hang too low on the back making it very hard, if not impossible, to reach your valves in the water.

Shoulder D-rings
The harness comes with multiple D-rings, some are straight and some are bent. Using the bent D-rings on the shoulder straps will make it easier not only for stage tank attachment, but for any accessory attachment. The bent D-ring should be angled outwards away from the body, making it easier for a P-clip or double ender to be fixed from underneath. Those bent D-rings should be fixed in place by one of the 3-bar sliders and should be situated at approximately the same height as the collar bone, or just slightly above your arm pit. The shoulder D-rings should be at the same height on both sides.

Waist Strap
Once the shoulder straps are correct, it is time to fix the waist strap. The waist strap is vitally important in securing the complete rig in place. The waist strap, unlike the shoulder straps, should be quite snug, as it adds to the stability of the harness configuration. It should be positioned around the waist at around the same height, or just slightly below, the naval. Straight D-rings with toothed sliders are fixed to either side of the waist strap at approximately 8–10cm / 3-4 inches from the backplate. The left D-ring is used for SPG and stage tank attachment. The right D-ring may also be used for stage tank attachement for divers who prefer the “left and right” configuration. If these D-rings are positioned too far back it will make it quite hard for removing or replacing any gear, but be wary, if they are positioned too far forward the stage cylinder will hang in front of the body causing drag and resistance.

Any accessories, such as line cutters or weight pockets, should now be attached to the waist band before fixing the buckle. The buckle should be positioned on the left hand waist strap, and in such a position that when it is done up and the waist strap is snug, the buckle will sit just to the right of the centre of the body, which will reduce the risk that the crotch strap accidentally opens the buckle.

Crotch Strap
The crotch strap, like the waist strap, should be snug, as it provides another form of stability to the configuration. Ensure that it is not too tight as that would not only pull the waist strap downwards, but it would also pull the complete harness and twinset downwards away from your hands when reaching behind you. This will make it harder to reach those valves!

Position the rear D-ring about 8-10 cm / 3-4 inches from the plate to allow for easy attachment of accessories that don’t get used so frequently. If the rear D-ring is lower than this, it will generally be hard to reach, and also any accessories clipped on will hang low between the diver’s legs making finning techniques more difficult and uncomfortable. The crotch strap comes with a fixed straight D-ring sewn into the webbing. This D-ring is for scooter / DPV attachment and should be on the outside of the webbing. No other accessories should be attached to this ring as the items will hang below the diver, posing an entanglement risk and increasing the drag on the diver.

Checking for Correct Fit
It is important to dry test the fitting of your harness with the full exposure suit that you plan to wear while diving on as this will have a dramatic effect on the shoulder strap sizing.

Of course, making these adjustments on land in your exposure suit will give you a good solid base for the correct configuration of the harness, but the true test is actually in the water.

The most efficient and safest method is with the help of your buddy or instructor in confined water. Make minor adjustments to the length of the shoulder and waist straps along with the crotch strap until you can gear up easily and remove the harness quickly. Don't be afraid to re-adjust the lengths based on in-water experience. Practice repeatedly clipping the SPG, primary regulator, stage cylinders and any other accessories that you will be carrying on an Extended Range dive. Adjust the position of the D-ring until everything can be performed easily and efficiently underwater.

During SSI Extended Range training there is an equipment configuration session where time is taken to ensure the correct assembly and fit of the backplate and harness. This knowledge provides the foundation for comfortable and safe decompression diving.

You can find more information about the full range of SSI Extended Range programs by heading to the SSI website or Tekstreme Diving.

Written by
Profile Cat
When 6th February 2019
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Stefan Michl on Feb 09th 2019
What an interesting blog. Learned a lot....! Keep on blogging...!

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