Category — Rebreather

Most cave divers may wonder at the beauty of cave maps and may even use them for cave dive planning but few have learned how to make cave maps. I recently taught yet another survey and cartography cave course with Dirk from Germany. We both used CCR Rebreathers as our primary breathing device during the survey portion of the training program. The goal at the end of the program is to have a published map in your hand, made from your survey data.

cave cartography

Most people would think cave map making and the process of surveying is only for cave explorers but if you have a cave in your neighborhood that is already explored, if there are already permanently guide lines installed but no cave map does exist you many want to consider a survey and consequently producing a cave map. Permanent guidelines do not have to be taken out in order to conduct a re-survey. Knotted line can be used for the distance measurement or fiberglass tape for greater accuracy. The NSS-CDS published a great book called Underwater Cave Survey by John Burge with all the details needed to survey and cartography.

Besides cave divers for dive planning there are other parties who may show interest in cave maps might be the land owner for him to see what he has and locations of potential wells, local governments to decide where certain installations such as gas stations and landfills may not be placed, developers to decide where not to construct due to danger of collapse and environmental agencies for natural reserve planning just to name a few.

cave cartography

A cave survey is a slow process and there are at least two ways to go about it 1) survey in and 2) survey out. 1) During the survey in technique the first diver is laying the survey line and the second diver is taking the survey data. The big advantage on this technique is that in case there is a problem the team can exit much faster than entering the cave and no survey data is lost. The survey in technique is a team effort and requires at least two divers. 2) During the survey out technique the line is laid on the way in and the survey is done on the way out resulting in a delayed exit and if the dive needs to be aborted then the survey is ‘hanging’, meaning the survey date is not connected to the starting point. The only advantage of the survey out technique is solo diving situations, with all of their particular advantages and disadvantages.

A cave survey as well has the potential for negative impact onto the cave environment as the dive is very slow and we need to get very close to the survey stations (tie off) as well as the line in terms of potential entanglement or breaking the guideline. Very good buoyancy, trim and propulsion techniques are a must for a cave survey. If a cave map does already exist for a particular cave one should not conduct a resurvey of the cave in order to protect the cave environment. There is no reason to fuck up a cave just to get the survey data and destroy what we love so much.

cave cartography

Once the survey data is collected the data needs to be saved on paper (my favorite) or electronically, or both. Line maps or stick maps can be produced in free software programs such as Compass. The data then can be imported into software programs such as Corel Draw and the map can be produced electronically.

cave cartography

My favorite way of making a cave map is the traditional drawing technique as I see the map as a artistically expression of the cave surveyor and cartographer. The first step is to draw a working map with all the cave information drawn onto milimetric paper. The second step is to draw a copy onto onion paper with all the cave information drawn onto the paper. The third step is to print out all the information shown on a cave map such as names, locations, index, scale, symbols and notes. The last step is to go to a copy shop and have your map copied and ready you are to publish your art work. You even can send a copy of your cave map to the NSS-CDS as they do a yearly competition for the most beautiful cave maps.

Taking the CCR Sentinel cross over the opportunity arose in March of 2010 when Nader Quarta from Switzerland came to Mexico to do some fine cave diving in the Riviera Maya. When we were setting up his dive trip he mentioned that he was coming with his Sentinel CCR Rebreather and I asked him if he is an Instructor on the unit. With a positive reply coming back I asked if he could do a cross over course with me while here and he was happy to do one for me while here in Playa del Carmen.

prior diving

The Sentinel CCR Rebreather is made in the U.K. and is the little brother from the larger Ouroboros CCR Rebreather. The Sentinel has a manufacturer depth rating of 100 meters / 330 feet and a very unique Co2 sensor detecting a rise in Co2 in the breathing gas should the scrubber material fail. The Sentinel is designed as a back mounted counterlung Rebreather, meaning you have the front of your body clean and the counterlungs protected within the casing on your back.

manual oxygen and diluent injector blocks

Back mounted counterlung Rebreathers are used to be not breathing so well compared to front mounted counterlungs due to the harder work of breathing effort as the counterlungs are a bit shallower then your real lungs, making inhalation a bit more difficult then exhalation. During the last years a number of new Rebreathers with back mounted counterlungs came onto the market with quite good work of breathing besides being a back mounted counterlung design. Keeping the front clean protects the counterlungs in case you want to penetrate small caves or wrecks. For photography and filming it is quite nice too as it gives space to bring the camera close to your face. Smaller people with not so much real estate might find it very comfortable as they are not so cluttered with the counterlungs in front.

solenoid assembly

The Sentinel is a bit bulky compared to other Rebreathers but is packed within a rugged design package, large bore breathing hoses and meaty construction components. All parts are fitted together in a way they can be individually replaced at a reasonable cost. The unit looks it is made to last a life time. A nice feature of the Sentinel is the location of the manual oxygen and diluent injector buttons located left and right on the chest within switch blocks allowing the plug in of additional offboard gases.

The two day cross over program started off with the unit itself, learning how to pack the scrubber and work the electronics, which are very different from all others I have used so far in terms of going through an electronic checklist that will let you only dive when completed poperly. In the afternoon of the first day we went to cenote Eden to get through a nice and long confined water session where I had ample time to get used to the Sentinel and work my way through emergency scenarios such as the three H’s of Hypercapnia, Hyperoxia and Hyperoxia as well as a boom scenario, SCR bailout and various electronic features.

unit in pieces prior diving

The second day we went to cenote Manati to complete the cross over program with two long dives where all emergency related drills and skills where repeated multiple times. When we started our diving that day the water was flowing quite strong out of the cenote through the tunnel and into the ocean. The current was so strong that we had to swim very hard against the water flow in order to get further into the open water area of the cenote.

BOV

I was very happy to be on a Rebreather as I had all the breathing gas in the world and was able to check out the work of breathing while swimming very hard for a longer period of time. At the beginning of the second dive I took the time to go through the complete handset menu various times. Very comprehensive, very sophisticated, very capable.

sensors inside the head

As Nad had asked me quite a view questions about the Classic KISS CCR Rebreather we have in the store I packed my unit in the morning and took it with me to the dive site in order to give Nad an introduction on the Classic KISS CCR. The water current was still very strong, actually the strongest I have ever seen in 15 years. While I was on an open circuit single tank Nad was happily on the KISS CCR and off we went for another dive, this time me being the instructor and Nad being the student.

pre-breathing the unit

I had a great time with Nad to learn once more something new and meet new people. The cross over program was very thorough with Nad being very knowledgeable about Ouroboros and Sentinel CCR Rebreathers.