Deco Habitat Design

[Dive Africa]

Hey there

I am a tec/cave diver based in South Africa, we are currrently exploring a system at 125m/410ft and to say the least, the deco is becoming a real PITA.

I am looking for some advise, technical designs, practical tips on: firstly how to design/build the habitat (I am leaning towards using a water tank) and secondly on how to install/fix it to the bottom etc. Advise on overall design and smaller things like seating position (and the like) would be really welcome.

The habitat is to be simple (also read: cost is an issue) no comms etc required and divers will stay on their rebreathers. It has to fit 2-3 divers - purpose is merely to find a warmer/dryer place.

Habitat to be fixed, i.e there is no need to hoist up/and down in water collumn.

All advise and ideas would be really appreaciated.

Regards Dries

[FW]

I have seen several. Most are "pinned" to the ceiling by the buoyancy of the gas in the habitat. They also are some type of water tight container, like large amimal watering troughs, large chemical containers, or something like a swimming pool liner, stretched over a frame.

[SuPrBuGmAn]

I'd like to hear more about your So African cave




Brett Hemphill built a neat habitat recently with seating, you may want to see if you can get his designs.

[BB1]

Hey Dries, Howzit??

These guys should be able to help you out: Wet Mules Their contact page is here

They are currently diving the Pearse Resurgance each year pushing further and further - 194m (636ft) so far and they use habitats for deco to escape the really cold water.

Heres a promo they did, you can see the habitats really well at about 3:50 into it, details of the seats they built etc are visible as well.

This is just about the habitats - it shows each of the 4 they use in the Pearse and how they're fixed in position etc.

Give them a shout and i'm sure they'll help you out!

For anyone else interested in the Pearse dive there is a downloadable 3D flythrough available on this page quite amazing what they have done so far.

[billyf]

Here is a pic of KUR's small Habitat that is installed in Madison Blue

[deepdiverbob]

If Chris, Shannon or any of the other members from the OCDA check this out, they can probably give you some ideas on the one they have constructed here in one of our local Missouri caves.

[mpoucher]

We used the designs from the Pearse Resurgence project for habitats built out of 250 and 350 gallon juice containers. They can be purchased cheap here, usually 75-125 USD and you just cut the top off. They come with a plastic pallet on the bottom and they are enclosed with a tubular metal cage. Not sure how the metal will hold up over time, but for the price, its not a big issue. Two people can easily move it around.

Brett Hemphill and Andy Pitkin came up with valve designs so the containers could vent without "burping" from the bottom - otherwise, the noise level is very annoying after a while. The containers have a threaded fitting at the bottom used to drain the tank and you can install pvc pipe and valves to allow it to drain. Andy used a simple downspout that can be adjusted to vary the water level in the tank and direct the exhaust away from the sides. It is self adjusting so once it is set, you don't have to do anything more. Brett's uses a valve you can access from the inside to adjust the gas flowing out. It requires periodic adjustment based on breathing rate, but worked fine and gave us something to do while decompressing.

Brett built triangular supports in diagonal corners with seats that can be removed. That the picture that Billy posted above. It got you fully out of the water, but the seats were a little unstable and we had to have a ladder to get up inside. But it was very comfortable once we got inside. His was a 350 gallon tank with a little more headroom. Andy used 2x4's as seats, which put you more in the water, but was still comfortable and very simple to install.

Both were pinned to the ceiling using natural buoyancy. Finding a good, flat place is critical. If the ceiling is very irregular, it is very difficult to get it leveled out. Of course we've only done this twice, but the containers are awkward to deal with underwater. One location was flat and installation was a breeze. The other had scallops in the ceiling and took a while to get it level and stable.

You'll want plenty of loops around the bottom of the habitat to hang tanks and stuff.

[Dive Africa]

Thanks for the replies so far.

One of our problems are that the cave entrance sits @ 12m and then enters open water. We will accordingly have to fix the habitat to the floor or to the sides of the open hole, an old quarry - Asbestos mine.

The cave/mine is well know (Komati Springs) was though to have been explored to its end. We however managed, a year or two ago, to break a metal door open (at 108m) with some crow bars and brute force. This door led to new passages at 108m and 125m which we are in the process of exploring.

Thanks Dries

[huxley]

how deep is the open water section? any way to anchor that habitat down to some huge boulders using chains? those water tote should have somewhere around 1000kg uplift (250 gal ones). If not you will need to suspend it down from some huge surface buoys or on at each corner, the water totes might work for that as well if they have the steel cage, hang some weights on each, lets say 300kg each corner and hang the habitat on those weights as well. Sounds like some real fun

[chilldive]

I have limited experience with habitats, but my experience with installing the current one in Roubidoux tells me that trying to affix one of these to the floor would be a major undertaking. The lift force of a filled habitat is huge.

Here's a few pics of our install. Due to the small opening into the spring, we had to assemble the habitat inside. Some pics show the aluminum panels on the ground. The inside is lined with a "huge bag" - kind of like an upside down above ground swimming pool. Seats are wooden. All probably more than you're wanting to do, but maybe this all helps some.

http://www.picturetrail.com/sfx/album/view/18244407

Our previous habitat was a simple box frame made of square tubing. Then a thick liner (bag) was filled inside the framing. It was light weight and probably low cost. But again the lift force when it was filled was huge.

If there is anywhere somewhat near your spring entrance where the ceiling rises to at least 25 ft, that would be best. Deco at 30' in a dry habitat would be fine.