Cave Diving, Cave Exploration and Cave Mapping in Yucatan, Mexico
Syndey Opera House and the Famous Bridge

Cave DPV with Steve Bogaerts

Editor’s Note: I want to apologize to my readers.  I posted this story in the middle of the night with some errors.  Particularly, I got my sac rate calculations wrong.  I checked my notes today and discovered I used more gas then I first thought and I checked my X1 average depth and realized I was using a deeper depth then it recorded.  — Hans

When I arrived in Mexico last winter, Steve Bogaerts and I developed a rough plan for my training. The training would include: Basic Sidemount, Advanced Sidemount, Cave Survey, Cave DPV, Stage/Multi-stage and CCR Hypoxic Trimix.  As of today, the only class I have left is stage/multi-stage.

We planned to spread the training over the course of a year and to pace it based on my progress.  My progress would be reflective of the number of dives I complete and the focus I put on practicing.  I am glad that I am a little ahead of schedule.  Today, I finished my 12th training day with Steve and we completed Cave DPV.

The Cave DPV course was a lot of fun.  I wasn’t as difficult or as stressful as some of the other courses, such as Advanced Sidemount.  Riding a scooter is like flying.  It is super cool to zip through the cave.

The DPV course took three days. The first day started with three hours of lecture.  We discussed:

  • Why to use a scooter
  • Safety issues
  • Gas planning
  • Emergency procedures
  • Team dive execution
  • Staging the scooter
  • Choosing a scooter
  • Batteries
  • Charging
  • Conservation
  • And a host of other topics.

After the lecture, we broken down Steve’s Silent Submersion UV-18 DPV and prepped it for diving.  The prep went something like this:

  1. Check the voltage of each battery. (13+ volts)
  2. Check the voltage of the combined batteries. (26 volts)
  3. Inspect and clean the o-ring and sealing surfaces on the motor end of the scooter.
  4. Inspect the motor compartment through the window.
  5. Ensure the cap is secure on the motor compartment.
  6. Attach the battery.
  7. Check to make sure the propeller is clear and the trigger is locked.
  8. Plug in the main connection.
  9. Plug in the secondary connection.
  10. Test the motor for less then three seconds.
  11. Attach the body of the scooter.
  12. Remove the nose cone, inspect and clean the o-ring and sealing surfaces.
  13. Disconnect the secondary plug for transport.
  14. Install the nose cone.

After a couple attempts, this ritual it becomes second nature.  I found it was best to work from the bottom of the scooter up.  If the scooter isn’t on a flat surface, like in the jungle, make sure to flip it over on the nose cone before testing the motor.

We also discussed predive check and break down of the scooters.  I am not going to give you all the procedures, because you will learn them when you take the course with Steve.  About noon, we got the gear loaded in his truck and we headed towards Tulum.  In Tulum, we stopped at Xibalba Dive Shop and picked up another UV-18.  I repeated the prep procedure and loaded the DPV in the truck.

Our first dive was at Cenote Car Wash.  When we arrived the water was tea colored.  I guess with all the rain we have been having, the swamps are unloading tanic water into the Cenote.   The first thing I needed to do was to get my scooter trimmed and weighted properly.  Steve walked me through the process and provided some helpful tips.  He recommended that DPV should be slightly positive with the nose slightly up.  If I was going to spend a lot time below the halocline then I should set it up a little negative at the surface with the same trim.

I was doubtful due to the limited visibility; however as soon as we descended we broke into clear water.  It was like coming out of the clouds.  The tannic ceiling provided a virtual roof and looked exceptionally cool.

We started off by doing figure eights and driving around.  Immediately I noticed how easy it was to manage this scooter.  I had driven a bunch of scooters including UV-18s and always felt awkward and hated it.  I felt like I was fighting the DPVs and I would be exhausted before we finished the dive.  This DPV was different.  It was balanced and I didn’t really have to hold the handle.  I could set the trigger lock and finger it.  I couldn’t believe it.  I had arrived.  It made scootering so much easier.  I just didn’t know it should feel this way, I figured you always had to fight them.

After I got over my euphoria, we moved onto staging drills, lights out touch contact and team communication.  After a couple of hours in the water we headed back to Steve’s place to break down the DPVs and charge them.

The second day we went to Ponderosa.  We made two cave dives.  We practiced installing/removing the primary reel, staging the scooters, team communication, low on air (tank swaps), exit on secondary light, zero visibility touch contact and other skills.  The first dive I wasn’t all that confident and kept stopping to wait for Steve to catch up.  This repeatedly broke rhythm and I blundered the scooter stage procedure.  I had forgotten the hand signals and couldn’t figure out what he was asking me to do.  After a minute or two of watching him do them louder, it came to me and we carried on.  The debriefing was insightful and to the point.  After diving we went back to Steve’s place, broke down the scooters and burn tested mine.  I had 7 minutes of burn time left.

Today, we went to Chac Mool.  Chac Mool is a big power cave with the largest known underwater stalactite.  It is about 90ft tall.  It is a 30 minute (1500ft) swim from the entrance.  I normally use about 42cuft of gas to reach it.  It is about the perfect scooter training dive because it provides an excellent benchmark to test again.  On the scooters pitched at 5 we reached the Monster in 14 minutes.  This included me bumbling with the reel and getting the tow strap entangled around my sidemount tank.

My swimming sac rate, in sidemount gear, is a .7 cuft/min.  I ran some calculations for my swimming dives to the monster and came up with .66.  Tonight, I calculated my sac on the scooter and was surprised to learn that my first dive was a 1.5 and my second was a .97.    Both of those are pretty hideous and leave huge room for improvement.  I think the task loading with the scooter during the installation of the primary reel really afected my sac rate.   I am definitely going to go and make some practice runs with the scooter to try and improve those figures.

A great example of the differences in our sac rates was our gas consumption at Ponderosa.  We scootered the River Run to the change in direction in the line arrows.  It took us just shy of 20 minutes.  In that time I used 450psi out of each tank and Steve used less then 200psi out of each tank.  I was shocked when he handed me his tank and he had used 200psi, I couldn’t believe it.

Besides keeping close track of our trigger time and gas consumption, we towed and towed some more.  Which is good because towing efficiently is harder then it looks.  Being towed is challenging because you have to stay out of the wake, control the scooter between your legs, maintain orientation to the guideline and not annoy your buddy.  Towing is challenging because you are like a semi truck moving through the cave. A semi truck with a failing tail that is apt to hit things if you are not careful.   It is like dragging a plow though the water. This is another skill that could use practice.

At the end of the day we headed back to Steve’s house to break down the scooters and burn test mine.  The burn test went 17 minutes and the Watts Up Meter showed we had 4ah remaining.  This correlated nicely, because the UV-18 has 16ah batteries and I had recorded about 60 minutes of trigger time.  That means we had about ¼ of the battery remaining and the total burn time would have been 77 minutes, which is in the middle of the 45-90 minute range.

Overall the course was a blast.  I really enjoy working with Steve.  He does a lot of this diving and spends a lot time thinking about the procedures.  Luckily, they are born of direct experience and you can feel that as you put them to use.  They just work.

I am glad to be qualified to use scooters now.  They will be an invaluable tool at The Pit.  I already have some other dives in mind.

Tomorrow, I start the stage/multi-stage course.  Since I dive in sidemount, we will do it in sidemount.  Hopefully, on Friday I will have something entertaining to report

7 comments

1 Jason { 10.09.08 at 11:14 pm }

Hi Hans, I must say, this DPV course sounds very interesting!
We met today at the filling station and you were on your way for multi-stage in Ponderosa. Can’t wait to read more about it!
Keep up the good work mate
Cheers
Jason

2 Etienne { 10.10.08 at 5:48 am }

Yesterday I was at cozumel whit some customer. One of them just went to a cenote excursion. He say that he was really impresse by to guys towed by some strange engine. I suppose it was you in chac-mool.

3 Jason { 10.10.08 at 6:34 pm }

Hi Hans,
That make me think that I WILL do the DPV course with Steve Bogaerts asap!
After I’ve seen few videos of it and read your descritpion of the journey….A must do.
Looking forward to read about the multi-stage by the way!
See you around, maybe at the filling station!
Bye

4 Hans { 10.10.08 at 10:57 pm }

Jason, Multi-Stage ended today. I wasn’t as successful as I hoped. I will try and write about it this weekend. However, we have a Pit dive on Sunday, so most of my weekend will be filled with that adventure. I can tell you that multi-stage was very difficult and presented some on foreseen challenges.

Hans

5 Hans { 10.10.08 at 11:05 pm }

Etienne , it might have been us. We went to Chac twice this week. We were also at Ponderosa this week a couple of times. Could have been in either place.

Hans

6 david { 10.11.08 at 7:15 pm }

Hans if you have a chance take a look just under the The Pit opening, maybe my fin is there in the bottom
david

7 Hans { 10.12.08 at 6:39 pm }

David, we couldn’t look for the fin today. To be honest, I never got in the water with scuba gear. We are planning to go back twice this week. I will try and look on one of those trips.