Franken-Rig Dive report

Frank in warmer weather. This was taken at one of my favorite beach-diving spots, Fort Weatherill, Jamestown Rhode Island. This is a perfect place for family diving.

On April 8th, 2001, I took the Franken-Rig out for its first test dive. The site selected was the benign waters of Dutch Springs Quarry, in Hanoversville Pennsylvania. The quarry was selected as it has good visibility, protected areas, and fairly deep water (70 feet plus) just a few yards from shore. The air temperature was in the low 40's and the water temperature was a chilly 43. Grey rain was falling as I pulled into the parking lot, and all in all it seemed a cold and miserable day indeed.

For this first dive, I used the rig with the original military "horse-collar" harness, and made no other changes to the rig as depicted in the main page. I added a 19 cubic foot OMS bailout bottle as a side-mount to fill my drysuit and to have a little open circuit bailout in case I might need it. That and the two internal cylinders (1 liter diluent and 0.7 liter 02) were all the gas I carried. Hey, I like to travel light!

After dressing into my ancient Viking suit, I donned the rig and added a shot or two of 02 from the manual bypass valve to set the surface PP02 at about 0.40 and pre-breathed for just a minute or two before slipping into the water. A quick leak and gurgle check, a check to make sure I had enough lead on, and down the line I went to the platform which is at about 20 feet. Once there I swam the perimeter of the platform, while watching the Draeger Oxygauge to monitor loop PP02. I manually set the PP02 with the manual bypass to 0.8 and let things settle in a bit. My impressions were of a nice rig, with good work of breathing, excellent balance, and good swimming characteristics. On the initial descent I was able to test the demand addition valve and I found it to work well, better in fact than my Mark-15. Work of Breathing did not seem to be affected noticeably by position, and all systems worked perfectly. I watched the PP02 level carefully while doing normal swimming and it never moved from the initial setpoint. This sort of worried me, as I was diving a single sensor CCR, and to test the cell I added a little 02 and the PP02 rose, so the cell was working fine. I then did a nose-vent and inhaled air against the auto-add valve and the loop PP02 dropped. The cell was fine, it was just that the 02 flow rate from the CMF orifice system was so closely balanced to my metabolic rate that it was keeping the loop set perfectly.

Once I was convinced that this thing was not a deathtrap poised to kill me, I dropped off the platform and did a free-fall descent to the bottom, at just slightly less than 70 feet. Once again the auto-add valve kept up with a fairly quick descent, and the rig balanced out fine. I had been concerned that the CMF regulator might not have sufficient pressure to produce CMF at a deeper depth, as the original application was for a shallow water pure 02 rebreather, but my fears were unfounded. At 70 feet +, as I swam deeper into the quarry, the PP02 stayed set exactly, and the manual 02 addition valve provided the same volume of flow that it had given up shallower. The flow of 02 into the rig is audible, and it was reassuring to hear the gas being fed into the counterlung. I detected no change in sound between the surface and 70 feet, and feel that the rig can be taken deeper without difficulty.

After about 10 minutes on the bottom I swam back to the platform, as my hands were getting sort of cold in the 5-finger gloves that I foolishly had selected over the 3-finger mitts I left behind. After playing there for a few more minutes, I did a direct ascent to the surface and then surface-kicked the 200 yards back to the dock. I deliberately kicked hard to see what the higher workload would do to the PP02 and in the 200 yards it had dropped only by about 0.01 from the 0.50 that I had when I hit the surface. Believe me, I had the Oxygauge right in my face the whole time I was kicking.

After climbing back to the truck, I checked the rig for water, etc., and found it was perfectly functional with no leaks, etc. I tossed it into it's box and got warmed up, all quite happy indeed with the outcome.

So, in closing: This rig works as advertised, and works well. I'd dive it tomorrow in salt water to 70 feet, and will be diving it deeper as soon as I am able, to determine the depth of maximum constant flow. Tonight I machined up an adapter to place my VR-3 into the loop, so I will have a second PP02 display, and then the last modification will be to machine an adapter to attach a pressure gauge to the 02 bottle. That's all folks, the rig is a blast, and certainly represents the best bang for the buck in CCR's today. I'll report further as I gain experience with this little gem, so stay tuned!

One of the nice things about Frankie is that he fits into a standard fish-tub for handling. These tubs, used by commercial fishermen to carry their catch, stack neatly and make a good place for doing leak-checks and for washing rigs as well. I get mine at a local commercial fisherman supply, down on the dock where the smell of unwashed fishing boats is strong, and where hundreds of well-fed cats can be found sitting everywhere. It's one of my favorite places. These tubs cost just a few dollars, are indestructible, and really protect the rigs in transport. Mark-15's happen to fit too, unless you use an ass-mount for bailout.