Cavern cert Limits?

[MauiScubaSteve]

I was certified NSS-CDS Cavern in '01, and my manual states the following limits;

Direct Sunlight Zone - diver can see the opening (entrance/exit). If you can not see the opening but it is not pitch black, you are in the ambient-light zone. When it is pitch black and you can see nothing without lights you are in the zone of total darkness. Cavern diving is only in the direct-sunlight zone.

130' Maximum Linear Distance from the Surface - Cavern divers must stay within a linear distance of 130' to the surface. Linear distance includes the depth of the entrance plus the distance of penetration. Examples; 30' deep entrance plus 100' penetration, 50' deep entrance plus 80' penetration, 70' deep entrance plus 60' penetration.

70' Max Depth - Below 70' air reserves for dealing with emergencies are too limited and the margin for error becomes too critical.

No Restriction - Buddy teams should be able to comfortably swim side by side. If divers have to swim single file due to localized narrowing that is considered a restriction. Cavern divers are not permitted to pass through restrictions in part because sharing air with standard scuba through a restriction is nearly impossible.

40' Minimum Visibility - The minimum visibility acceptable for cavern diving is 40'.

No Decompression Limits - Cavern divers should stay well within the no-deco limits. When cavern diving, bottom time is the time from leaving the surface until returning from the cavern to a depth of 10' in open water(not ending at start of ascent). Most experienced cavern divers stay within 80% of NDL limits, to allow for any unexpected delays during exit.

Air Supply Limitations - One of the three leading causes of death in underwater caves is failure to reserve adequate air for exiting. This requires at least as much air in each cylinder as both divers (buddy team) used coming in on the two seperate cylinders (basic rule of thirds).

If I find a NACD Cavern diver to dive with I am wondering what are the differences in our training limits.

For example; my cavern manual says I am beyond cavern diving if I can not see the entrance/exit, the ambient light zone is cave diving teritory. A crack in the roof that I could directly see the sun through, but could not dive through in buddy formation (restricted), does not change it from being the "ambient zone." Only direct sight of the entrance/exit makes it the "direct sunlight zone."

The third person NACD Standards I have seen have just said "The Cavern Diver must always stay within the daylight zone of the cave system. While it is not necessary to have view of the physical opening to the cavern, clear view of ambient light radiating through that opening must be plainly visible."

I am also wondering if how long ago the Cavern cert happened makes a difference for NACD? Current NSS-CDS Cavern limits are different from my 10 years ago NSS-CDS Cavern limits.

 

[gsk3]

While we're at it, do cavern certs expire like apprentice cave certs do, or are they good for life like OW certs tend to be?

 

[boulderjohn]

While we're at it, do cavern certs expire like apprentice cave certs do, or are they good for life like OW certs tend to be?

With NSS-CDS, Basic and Apprentice expire, but Cavern does not.

 

[gsk3]

Good to know, thanks.

 

[NACD]

Below is a link to the NACD website that gives some information on the cavern course. The limits on the NACD Cavern certification are:
1. Depth is limited to 100 feet,
2. No more than 200 linear feet from the surface,
3. Must stay within the daylight zone of the system,
4. No decompression or restrictions,
5. Limited to 1/3 of a single cylinder or 1/6 f doubles if permitted, and
6. Minimum visability of 30 feet.

The cavern certification does not expire.

NACD Training

Sandy Robinson
pr@safecavediving.com

 

[MauiScubaSteve]

Could you define "daylight zone" for us please?

 

[Peter Guy]

Hale -- when you ask for the definition, you might also let the person know you are not referring to a "traditional" cave (i.e., a hole in the ground) but instead to a lava tube which may only have one entrance/exit but many light holes. My guess, and it is only a guess, is that the 200 foot linear distance from the surface may be the primary limiting factor in your case. Although, who knows, maybe the "daylight zone" requires being able to see the light from the exit (entrance) which may well be hard to define in the tube case where you have a lot of light.

 

[rjack321]

I thought Sandy was pretty clear, you don't have to see the exit just daylight therefrom.

Could you define "daylight zone" for us please?

Do you really have a a situation where:

1. you are within 200ft of the surface,
2. able to see daylight but that daylight is not from the exit its from some other impassible opening
3. you can't see the exit's daylight anymore?

I know places in Mexico where this applies (Taj Mahal), but the "impassible opening" is an air dome where you could wait for rescue if you were hopelessly in trouble. So its an exit, you just can't get out of the water. MX has its own rather generous definitions of a cavern anyway.

 

[stairman]

In the case of other light coming in the rule remains the same. 200 ft from the entrance, which is where you tied your reel in at.

 

[MauiScubaSteve]

In the case of other light coming in the rule remains the same. 200 ft from the entrance, which is where you tied your reel in at.

What if the "other lights" are not exits but they give you an "ambient zone." Then I go to a point just less than 200' linear, a point I have been to also just less than 200' linear from the other exit, also with the same-ish ambient lighting.

Less than 400' linear total, and never more than 200' from the surface, but not actually seeing the exit past 80' linear. Numerous corners from seeing the exits in both directions from near the middle, but only a couple small dead end bubble pockets off the tube.

In that above example, there is nearly 200' traveled that is not within sight of the light from an exit, but it is all ambient lit. So If I am mentoring a NAUI Cavern Diver who claims his limits are the same as a NACD Cavern Diver, taking him through the above example is not setting a bad example?