Weeki Wachee and Lineater

[JonG1]

I have been following some of the posts on social media about the exploration of these sites and the distances, depths, durations and deco requirements (alliteration was unintended) are phenomenal.

I'd be very interested in how the logistics stack up in terms of rebreather durations, bailout options and calculations, decompression plans used etc.

I think they are using Fathoms(?) but still cant see how a 16 hour exposure can work even allowing for some habitat time.

 

[Doby45]

A single Fathom with a 9lb scrubber could last a LONG time while you are scootering. Also go back and read exactly how long they were in the habitat.

Edit:

The FB post states 420min when they got back to the habitat, that is 7hr2min, so the other 9hrs would have been spent in the habitat.

 

[JonG1]

It was 8 hours wasn't it I thought BT and deco were roughly same?

So Fathom holds about 4kg, is that as standard?

 

[flymolo]

Could you post links to the FB posts? I'd love to check them out.

 

[Doby45]

It was 8 hours wasn't it I thought BT and deco were roughly same?

So Fathom holds about 4kg, is that as standard?

The Fathom uses the Meg radial scrubbers, so you can use the 5.5lb scrubber or the 9lb scrubber.

 

[JonG1]

Brett B Hemphill

 

[kensuf]

Brett uses a Fathom, Andy is using a Meg. At Lineeater they are also bringing bailout rebreathers and using two habitats at different points in the cave with it's own scrubbing system. At Twin Dees the bailout rebreathers are also being used, plus a habitat at 40' -- there's been talk about installing a second habitat deeper into the system but the logistics at Twin Dees make that very difficult.

 

[rjack321]

The Fathom uses the Meg radial scrubbers, so you can use the 5.5lb scrubber or the 9lb scrubber.

The larger Meg radial is 8lbs

"Gas mix: Air, Depth: 132fsw/40msw variable depths, Water Temp 55°F/13°C, CO2 production: Variable. Kick and glide recreational level of swimming exertion. Time 8 hours."
Megaldon Scrubber Options - Innerspace Systems Corp

The 8hr duration is for water 13-15F colder than typical FL cave water (~69F). Between the scooter and the warmer temps you end up with >8hrs. I don't do these kinds of durations (or water this warm usually) so I dunno what a good max max is.

 

[kensuf]

The problem with saying "this is the max!" is there are several variables that can move that max point from one day to the next. Workload of the diver, the way the scrubber was packed, the condition (age?) of the sorb, etc all play a part in absorbent duration. This article, How Long Will Your Rebreather Scrubber Canister Last? , is interesting to me because 5 runs under "identical" conditions produced 30 minutes of variance.

 

[rjack321]

The problem with saying "this is the max!" is there are several variables that can move that max point from one day to the next. Workload of the diver, the way the scrubber was packed, the condition (age?) of the sorb, etc all play a part in absorbent duration. This article, How Long Will Your Rebreather Scrubber Canister Last? , is interesting to me because 5 runs under "identical" conditions produced 30 minutes of variance.

Well sorb doesn't have an infinite CO2 capacity. The theoretical maximum for 797 is a little over 150L co2 per Kg IIRC.