DPV's and Cave diving

[Web Monkey]

<This thread has been split from the cave divers killed at Eagle's Nest thread - Snowbear>

It would seem that a DPV would be a really good way to get killed, since it would let you go much further into a cave under power than you could swim back out un-aided.

This means that if it fails, you can't swim back out using the amount of gas you planned.

Do people really use these for caves? I always thought they were just for playing with in the pool.

Terry

DPV Diving Propulsion Vehicle. Basically an electric motor & battery with a propeller on the front and handles on the back. A diver holds it in front of him and drives it. Much faster than swimming. In this case DPV (Dead Person Vehicle).

 

[Rick Murchison]

It would seem that a DPV would be a really good way to get killed, since it would let you go much further into a cave under power than you could swim back out un-aided.

Properly planned and executed cave dives using DPV's don't go further into a cave than the divers can swim back out unaided. Nor does it appear that that was done in this case. This is at present a complicated accident whose root cause is as yet unknown. Some of us I'm sure (myself included) have formulated possible scenarios that could explain what has been found so far - but we're just gonna have to be patient and wait for the guys on-scene who are familiar with the system, the divers involved and the detailed evidence they've been able to piece together to find out what most likely really happened.

All the details will be released once the recovery divers have made their reports and the sheriffs dept gives the approval.

Until then, we wait.
Rick

 

[Fivetide]

The guys that I have dived with who like caves ( I don’t like to cave dive a. Cause if I cant se the surface I don’t want to be there. And b. I’m to big –wide-long- etc) have said that they wont allow DPV’s because they can kick up a lot of silt in narrow areas and as has been said before make you go further than the unlaiden return is possible. However they do know cave divers who use them for illumination ( think the ones with lamps on the front) and hauling spare tanks.. which seems reasonable to me as it saves the divers energy as long as they are not relying on them for the return journey.

 

[Rick Murchison]

they wont allow DPV’s because they can ... as has been said before make you go further than the unlaiden return is possible.

A DPV can't make you go anywhere.
Rick

 

[IndigoBlue]

A DPV can't make you go anywhere.
Rick

While we are awaiting further details, I am wondering what the acceptible conventions are for DPVs in caves. Offhand I would think that the normal "2 of everything that is critical" criterion would be required.

Therefore either having a backup DPV of your own, or else being able to rely on your buddy's DPV to extract you both, would be needed, if diving into a cave with a DPV were to be done safely.

Any observations on this by any NACD instructors?

 

[chickdiver]

While we are awaiting further details, I am wondering what the acceptible conventions are for DPVs in caves. Offhand I would think that the normal "2 of everything that is critical" criterion would be required.

Therefore either having a backup DPV of your own, or else being able to rely on your buddy's DPV to extract you both, would be needed, if diving into a cave with a DPV were to be done safely.

Any observations on this by any NACD instructors?

Ideally when utilizing DPVs (especially deep) a team of 3 is used. One tow scooter (spare) is carried per team. In the instance of a team of 2, 2 tow scooters should be used for redundancy. It is entirely possible to tow a diver on a DPV without "overloading" it (I personally have been towed for 5000' - that's not a typo- in Mexico). Towing divers and spare scooters are skill practiced on a regular basis.

Scooter maintenance is also paramount. Batteries must be burn tested periodically, so that you are 100% sureof the battery life (burn time) of a particular pack. Dive planning involves battery life as well as all the other factors typically taken into consideration.

 

[scubafool]

"Ideally when utilizing DPVs (especially deep) a team of 3 is used. One tow scooter (spare) is carried per team. In the instance of a team of 2, 2 tow scooters should be used for redundancy."

Chickdiver,am I misunderstanding, or are you saying that a group of 2 should have more spare DPV's than a group of 3? It doesn't sound right to me, but maybe there is some aspect of the situation that I am not understanding? Honestly not looking to argue, just seems odd to me.

 

[IndigoBlue]

Ideally when utilizing DPVs (especially deep) a team of 3 is used. One tow scooter (spare) is carried per team. In the instance of a team of 2, 2 tow scooters should be used for redundancy. It is entirely possible to tow a diver on a DPV without "overloading" it (I personally have been towed for 5000' - that's not a typo- in Mexico). Towing divers and spare scooters are skill practiced on a regular basis.

Scooter maintenance is also paramount. Batteries must be burn tested periodically, so that you are 100% sureof the battery life (burn time) of a particular pack. Dive planning involves battery life as well as all the other factors typically taken into consideration.

Thank you, Chickdiver.

 

[chickdiver]

"Ideally when utilizing DPVs (especially deep) a team of 3 is used. One tow scooter (spare) is carried per team. In the instance of a team of 2, 2 tow scooters should be used for redundancy."

Chickdiver,am I misunderstanding, or are you saying that a group of 2 should have more spare DPV's than a group of 3? It doesn't sound right to me, but maybe there is some aspect of the situation that I am not understanding? Honestly not looking to argue, just seems odd to me.

Yes, 1 tow scooter per team of 3, 2 tow scooters per team of 2 is correct. The idea being tertiaty redundancy. It allows for failure of a maximum of 3 scooters in each instance (a highly unlikely event). Undoubtedly, scooter reliability varies by brand and owner maintenance, but my experience has been that they are very reliable. In several hundred dives conducted in both deep cave and deep ocean environments, I have experienced only 3 failures.

 

[JDostal]

Gas management is also different...

I haven't taken any scooter training myself, so don't have first hand knowledge fo the gas planning, but I've heard that the thirds rule goes out the door and you start looking at sixths.