New Sidemount Options

I rarely write reviews of kit; however, I had an opportunity to dive two new sidemount harnesses last week. One a prototype of the HOG/EDGE SM system; the other the new SMS75 harness from Hollis. I wanted to share first impressions since my experience with the out-of-the-box usability of most SM rigs is one flavored with frustration and compromise. Both of these new offerings show some promise in my opinion, and both suited me and my style of diving well.

For the record, I was diving in Jackson Blue (a North Florida cave) wearing an O’Three 1-100 drysuit and using a borrowed set of Worthington low-pressure 17 litre / 108 cft cylinders, and carrying an aluminum 40 cft cylinder for decompression gas. On the off-chance that you are not familiar with these steel cylinders, each has a surface empty weight of a little more than 20 kilos.

First, the Hollis SMS75. I’ve been waiting for a chance to see and dive this rig since being told about its development earlier this year. As with all the Hollis gear that I’ve used over the years, the SMS75 is well-built and looks like it can take abuse, which for a sidemount rig is essential. The basic design at first glance looks similar to the SMS50 but there are several key differences. To begin with, more buoyancy with the emphasis on getting the diver’s hips and arse up without resorting to sticking trim weights on the shoulders. The rated lift provided is stated as 45 pounds (about 200 Newtons or 20 kilos). I have not tested that rating but I was near bladder capacity wearing the tank package described above in fresh water.

Next is the harness. The shoulder harness is connected to the waist band webbing via two adjustable retaining buckles rather than disappearing under the armpits and attaching somewhere uncomfortable close to the diver’s back. This design is more stable and delivers better control and is essentially a rethink of the “classic” steel or aluminum BP harness routing that I find cuts into my armpits. While most SM designers have adopted a follow the leader approach, it’s refreshing to see that both Hollis and HOG have given this aspect of their rigs some thought.

Another difference between the SMS50 and the 75 is that the SMS75 comes with “old school” bungees (also known as armadillo style bungees). This style of bungee (when properly adjusted) has the advantage of keeping the top of a diver’s primary bottles where they belong and not sliding around shifting balance points as the diver reorients him or herself to navigate restrictions.

The final chance is that the inflation hose is flexible rubber with an oval cross-section and not the hard, inflexible circular trash used on many rigs… including other Hollis rigs.

Other hardware seemed adequate and perfectly serviceable… without any need to resort to scissors and duct-tape.

One potential drawback of the Hollis system is that I’ve been told it’s available in only one size. It fitted me perfectly, but I’m more or less “stock” size (180 cm tall).

The prototype HOG rig has been back and forward between the workshop, drafting table and test group for more than a year, and is finally due for its official launch around Christmas 2013. Because of this, it’s not really practical to offer anything close to a blow-by-blow of the system I dived, except to touch on some design features that I believe will make it to the final product.

Harness innovations are similar to the Hollis SMS75 which is due in great part to the fact that Edd Sorenson consulted for both companies — and in fact dives regularly with BOSS HOG, Chris Richardson. The lift that HOG is aiming for is a few pounds/kilos/tens of Newtons more than the Hollis, and the unit I used delivered about 55 pounds of lift, again focused on the lower back and hips. The shoulder dump was pouched on the demo/prototype so I was obliged to rotate and use the LP inflator unit to dump gas. This made for a couple of less than stellar moments during a couple of days use, but obviously should not be a concern on the “real thing.”

Again, similar to the SMS75, the HOG unit had the smaller, higher profile Tech “door handles” on a wider than normal butt plate. This positions the anchor points for the primary cylinders close to the top of a diver’s hip bone rather than a few centimeters lower down and closer to the spine. This is a good option for most of us but I can see it presenting a mildly annoying cylinder trim challenge to those who dive aluminum cylinders.

The HOG unit has adjustable crimping bungees to control the distribution of lift… a little… and also has a smooth replaceable cover over the whole of the buoyancy cell. Jury still out on this. It’s “required” because of the bladderless construction of the HOG wing, and did not get in my way. I simply reserve judgement until I see the final product.

Both the HOG and Hollis were fitted with a Y-style crotch strap rather than the single 2-inch webbing “be careful of the family jewels” option that most every other SM unit uses. I love this type of harness and find it way more comfy and the better option for being pulled by a scooter. Not sure if this will be the default with full production units. If it’s an option, I will ask for it.

Overall, BOTH these units seem VERY well-designed and functional. The SMS is useable out of the box if the unit I used is any indication. The HOG has a couple of “minor edits” before full production for an end-of-year delivery… but Chris tells me they will be done.

My final take is that I will be replacing my existing SM units (ones loaned to students in workshops and clinics) with both the HOG and SMS75, and I while I will keep my SMS50 for a light travel unit, my personal SM rigs will be replaced with a HOG and an SMS75 before I get back in a cave (or wreck) in open-circuit gear.