Rob's NJ Wreck Diving Blog: July 2009

I’ve an appreciation for old cars, having restored an old karmann ghia, as well as a VW camper. My hope with this rig was to replicate that experience, refurbishing and updating this venerable 40 year old design. I’m pleased to say that the experience was pretty much just what I had hoped it would be, a satisfying immersion into a very different kind of rebreather. Nothing is ever really done, but at this point I've got the 15 pretty much just the way I want it. I took a few pictures showing how it is setup in case anyone is interested in seeing it.

I originally bought this rig last year, since I needed the spheres for my sidemount prism. It was built in 1980, and based on the sensor dates was last dived in 1994, then thrown back into its case wet. Fortunately it fared pretty well despite the neglect. One loop hose was rotten, but oddly the other was fine. Most importantly the counterlung remained in pristine, albeit smelly condition. It took many washings in soapy water and disinfectant, and even a little mouthwash now and again, to get it to finally stop stinking. The plexiglass cover on the analog primary was opaque when I got it, due to some sort of incredibly tenacious mold on the underside. I wound up getting an aircraft cockpit cleaning kit, and running it from 300 grit all the way to 5000 or so. It did the trick, and is now quite clear.

My reaction after examining the stock Scott DSV was that it would be most appropriate for my son’s toy rebreather. I've also slowly gone over to the BOV mentality, so after doing my research I decided that I liked the cut of the JJ's jib, and ordered one. The BOV is fed from off-board gas, using a quick-disconnect. Earlier I had bought a set of Cooper hoses in the stock size, but there was no way they were going to fit Dave Sutton’s adapters, much less the very oversize fittings on the JJ BOV. As such I picked up a set of regular rubber hoses from Golem Gear, which are a bit longer than I'd like but are otherwise perfect.

I did one dive on the stock harness. It was way too uncomfortable, so I contacted Enrique Alvarez and had him make up one of his excellent SS harness plates, along with a Titanium bottle bracket. My goal for this rig is to keep everything very clean and very simple, and therefore I have elected not to use a wing with it. It's been a while since I've dived using just a drysuit for buoyancy, but it's like riding a bike. In keeping with the minimalist aesthetic I also chose not to run spg’s down to my chest d-rings, and instead have a couple of button gauges on the regs. For weight I have one of Rick’s 9# pizza weights, installed inside the case and held by the harness backing plate. It is painted it with black plastidip, which further softens the edges. I dive the rig with a dui laminate suit and weezle extreme plus underwear, and the weighting is spot on, just heavy enough that I won’t have to change anything for salt, but light enough that my drysuit never feels uncomfortably inflated, even with two stages. In addition, the dreaded Mk15 butt-heaviness is simply gone. Trimmed, weighted, sorted.

I did one dive on the stock harness. It was way too uncomfortable, so I contacted Enrique Alvarez and had him make up one of his excellent SS harness plates, along with a Titanium bottle bracket. My goal for this rig is to keep everything very clean and very simple, and therefore I have elected not to use a wing with it. It's been a while since I've dived using just a drysuit for buoyancy, but it's like riding a bike. In keeping with the minimalist aesthetic I also chose not to run spg’s down to my chest d-rings, and instead have a couple of button gauges on the regs. For weight I have one of Rick’s 9# pizza weights, installed inside the case and held by the harness backing plate. It is painted it with black plastidip, which further softens the edges. I dive the rig with a dui laminate suit and weezle extreme plus underwear, and the weighting is spot on, just heavy enough that I won’t have to change anything for salt, but light enough that my drysuit never feels uncomfortably inflated, even with two stages. In addition, the dreaded Mk15 butt-heaviness is simply gone. Trimmed, weighted, sorted.

The Rev G electronics were a big tease on the bench, looking like they were going to function, but when I got them in the water they crapped out. After pondering the various electronics choices I elected to Hammerhead mine. I'm very comfortable and familiar with the Hammerhead, which is important since I don’t anticipate this ever being my primary rig. In addition, I liked the simplicity of the installation; the speed with which I could get a setup from Kevin (he had one on the shelf); and the pedigree, since Juergensen Marine has been supplying them for the latest Mk16 incarnation. Except for having to reverse polarity the installation was quite simple.

I knew I wanted a HUD, and thought long and hard about putting a Meg HUD on there. Due to the extra expense and delay I went with the DIVA, though I'm not sure if I had to do it again I wouldn't go the other way. As you can see in the pics, the lever on the JJ BOV has been drilled and tapped to hold the HUD, which couldn't be nicer. In closed circuit mode it is held firmly in place, unobtrusive but in the line of sight; in open circuit mode it is pushed down and out of view. It is held on by a couple of knurled knobs, which make it easy to remove when cleaning the hoses.

I’ve been diving sidemount bailout for several years now, so there was no way I wanted to pollute a lovely BMCL setup with bulky sideslings. At my request Enrique welded on a couple of D-rings to the bottom of the bracket, and I ran some grommetted webbing and bungee through the harness bales. It still needs a bit more futzing to get them exactly where I want them, but it’s darn close.

I did a quite a bit of research while sorting the unit, and will list a number of links below that I found most useful. Thanks to everyone on Rebreatherworld for their suggestions/help/advice, and especially to Dave Sutton for spending a couple nights with me sorting the electronics, fitting the HUD, etc. I couldn't be happier with it.

LINKS:

Here is the official manual, in several parts:
http://www.rebreatherworld.com/attachments/mark-15x/1477d1144696914-mk15-analogue-electronics-mk15-ccr-electronics-part-1-7.pdf

http://www.rebreatherworld.com/attachments/mark-15x/1478d1144698120-mk15-analogue-electronics-mk15-ccr-electronics-manual.-part-2.pdf

http://www.rebreatherworld.com/attachments/mark-15x/1480d1144698603-mk15-analogue-electronics-mk15-ccr-electronics-manual.-part-3.pdf

Dave Sutton's MK15 Teardown:

http://www.nobubblediving.com/mark-15.teardown.htm

Andrew Donn's MK15 Teardown:

http://mysite.verizon.net/adonn/Rebreath.html

A comparison of the MK15 and later MK15.5

http://www.deepdiving.net/15/15v155.html

Stuart aka Lizardland's Teardown and Hammerhead Installation:

http://www.lizardland.co.uk/MK15/HH_installation.html

Enrique Alvarez's MK15 parts:

http://www.techdivetools.com/rebreather/navy_mk15.html