Monday, January 14, 2008

Freediving Liftbag - my experiment from the later ninties

Now that the sea is still pickled I will wonder back into one of my past exploits. In the mid to late nineties I was a keen freediver - doing deep dives to expand my abilities and pushing long breathholds in the pool.
Getting down with a weight and then up with a liftbag always looked very exciting to me. I decided to make my on liftbag and have some fun trying it out.

here is what I did:
1. Sacrifice: I sacrificed my homemade CO2 gun - it consisted of a soda water generator bottle and two valves - the first vale released CO2 into a chamber with another valve keeping the gas in. The second valve was connected to a trigger mechanism I made for rapid release of the gas which drained into a 12 mm tube and pushed out a 10 mm spear - a very powerful gun indeed. Heavy though I often dives with one or two weights only. Without a pressure gauge my shot at a big yellowtail came to grief as the spear just cleared the barrel and then sank down onto the redbait. This danger was in the back of my mind when converting it to a lifter.

2. Restructure:
I removed the barrel and cut open a large inflatable buoy I had (A Rob Allen one - sorry Rob!) Anyway I fastened this buoy in a deflated form onto two straps and connected a cylinder to the gas gun mechanism with the second valve open to allow the gas to fill the bag.

3. Test: I made a heavy belt - 8 kg and got Mark to take me out to about 30 m on his boat Indica, his girlfriend Ros was also out with us. I chose 30 m as I knew i could easily get back up even if the device failed and I kept my belt on. I donned my new device and took some deep breaths and headed down in the cold and dirty water. I reached the bottom and looked around - rather boring so I opened the valve and the CO2 hissed out slowly I began rising and was soon lifting and a splendid pace - I popped quite high out the water and dropped back in well-satisfied with my device. I only got one lift out of it and the gas was spent.
I decided that lifting with the rather unreliable CO2 canister was probably too risky for very deep water where a diver would be dependant on the lift - imagine getting not lift when you turn the valve.

The next step was to make a homemade sled to pull down fast with a piece of railway line.

I will scratch around the garage for remians of these items and take some pics and post them - maybe even get them in action again - yes that is a good idea.


Anthony said...

Hi, I see Eugene caught a nice cob the weekend when he took his daughter out at Noorthoek. I went to the Ryi banks but no good fish came out. I hope the water clears up soon so you can go out.

Gletwyn Rubidge said...

Hi Anthony,
From my experience you need to find where the cold and warm water meet preferably over a good reef or else you are often fishing in a desert. I think you should lower a min max thermometer gently to teh depth you fish at and pull it up see if your bait is in the cold water. Better still dive down and find the cold water then get back on boat and fish at teh edge of the thermocline. How was the water colour on the banks - vrot I guess.