build your own bouncing betty=no limits fun!

[Crypple]

Gday All,

I'm not niave enough to think this is a first or anything... but we have been having a lot of fun with this particular contraption. Currently hitting 40 meters the tank is good for 6 to 8 lifts. With safety divers are onhand this is a simple rig for good fun and depth training!

I'd like to hear about more homemade contraptions out there (come on, you know you've got 'em!)...

Cheers
Crypple

 

[johnny]

Hi Crypple,

do you not attach it to a line to go up and down?? is it just free??

can you post some close up pics of the equipment used and how you configure it all together, it would be very much appreciated.

would love to give it a go. Thanks.

Johnny.

 

[Crypple]

Gday Mate,

At first I attached a line until we were sure it was going to work as planned. The main safety problem I had with the line was the possibility of entanglement (as a tech diver I'm always thinking about that stuff!) so we used nice thick line that wasn't prone to knotting (see picture) running over a pulley with a small counterweight on the free end... However like I mentioned we're not going extremely deep at the moment and I am comfortable diving to this depth unassisted so after a few sucessful test runs I decided to go untethered as equipment loss was no longer a huge factor (we are hitting a sand bottom).

If you try this with a line make sure the line is free of your body and your gear is as streamlined as possible to reduce the chances of an accident. Always have a buddy with you as well! If you are diving in the big blue I advise mounting a depth guage on the tank and doing a number of test dives with "bail out" situations for example dive 10 meters and turn on the tank to reverse or slow you descent.

I used a small scuba cylinder (4 litre) with a fill whip from a compressor system jammed up into a 50 pound lift bag (make sure the whip can't come out on the drop). I found 16 lbs to be ample for negative ballast. If you use a rope you can clip it off to a float on the surface while breathing up, if you go free inflate the lift bag on the surface then upend to begin descent! When you hit the bottom turn on the tank for no more than a count of 3, remember the air volume in the cylinder is highly reduced beyond 4 ATA. I found the 4 litre good for 6 to 8 drops.

Hope this helps, please keep in mind I am definately no pro, but this works for me and it's a bloody good fun!!

Crypple

PS HOLD ON!!!! :duh

 

[johnny]

Thanks very much Crypple , looks like a real fun toy.

you go down to 40m with those scuba fins??? WOW you look fit dude.

i think i'll put my mono on just in case.

Right i am off to the dive shop to scrounge some gear.

Nice one.

:wave

 

[Crypple]

Ha! No worries mate... have fun with it!

And yeah the fins are a bit mini, big Cressi's on the cards when I get back to the real world in a week (good gear in Honduras is hard to come by!)

PS Me and my mate officially christened it the "Morning Stiffy" as we have to get up at 5am to go freediving before work!

 

[cdavis]

Hi Crypple, looks like great fun.

We have been experimenting with a simple variable ballast set up, a 20 pound chunk of lead on a long braided rope. 35 meters so far and the rope will go to 50 meters. Also great fun. My eleven year old son thinks it is a blast (he's down to 15 meters) The only negative is hauling it back up after every dive. I'm thinking about how to rig a power winch.
It is very strange to get to the bottom of the dive having spent so little effort that the urge to breath is no where near started.

Connor

 

[Crypple]

Gday Connor,

Sounds like the rig we've set up to compensate for very substandard fins! Have you thought of a simple pulley/counterweight system? I rigged one up to a life bouy (ring). Basically find 2 pulleys that run you rope really smoothly, run the rope thru both pulleys. One end of the rope has your heavy weight the put a 2 pounder on the other. This eliminates the chance of entanglement in the surface line and by spreading the pulleys apart you won't injure yourself on the counterweight! Also by lying on the float you can easily pull the descent weight up without straining too much. Try clipping the weight off with a quick release to hold it until you are ready to go. You'll just need to experiment with ropes and pulleys to reduce the drag of the rope.

Hope this gives you some ideas! :hmm

Crypple

 

[Polorutz]

Be very careful with that toy... It may work well for not so serious training... but in VW as well as in No-Limits being able to slow your descent is VERY critical... in sleds it is done by cranking a little knob... in your gadget its freefall all the way... don't go anywhere near your limit... be VERY careful.

 

[Crypple]

I'm interested to know the desirable descent rate used in VW and No limits. Obviously speed increases with depth/lung and wetsuit compression but is there a terminal velocity and how close should we be approaching to this? I read somewhere on this forum that 1.2m/sec was about right? And yeah we're being very careful, only ever using it with at least 2 supports, we're all experienced dive instructors and recreational spearos... and all freediving is over before we get on the bubbles!

 

[Polorutz]

Ok there is no problem as long as you know what you're doing and clearly you are but the advice still stands...

For the limit on descent and ascent rates I don't really know because I don't personally do n/l or VW, I've trained with Carlos Coste so maybe I can ask him about the VW descent rate...

I'd check musimus site... I think I saw a dive graph from the D9 he used on his 209m dive.

 

[DeepThought]

Descent speed limit is something personal.
The two limiting factors that I can think of are keeping up with equalization and not getting a lung squeez (which I'de be also very afraid of). Both are personal adaptations. I don't expect to be able to descend at the amazing speeds Partic did (or other deep NL/WR divers), those kind of speeds require adaptations such as ribcage flexibility and pulmonary vessels flexibility (I'de assume).
You will have to start slowly and increase speeds gradually over dive sessions.

Another thing to consider if doing a lot of deep repetitive dives is DCS. This risk is still in the dark for us freedivers, no one really knows what are the safe depths/number of dives/interval times. You can try posting them and maybe some one with more experience could make an assumption.

 

[Crypple]

Actually that's what I was really surprised to see when scrolling thru this forum... Getting bent while freediving? I'm well schooled at decompression theory having trained to operate recompression chambers and conducting many mixed gas dives past 300 ft but i'd never thought about DCS from free?! Thinking about it tho it makes sense, if someone can upload a link to said tables (in a similar thread a while back the link was broken) that would be great.

Anyone have a link to Patrick Musimus' site?

 

[DeepThought]

I aim to please!

http://www.patrickmusimu.com/
http://www.patrickmusimu.com/TUD.html

Never saw any freediving tables but the famous static training ones. I think there aren't ones.

 

[Crypple]

According to the tables he has published his descent rate is a little over 1.8 m/sec with an ascent rate exceeding 2.8 m/sec! That's incredible stuff but obviously not something easily (dare i say ever) replicated.

Our dive shop works closely with DAN (Divers Alert Network) and we have a representative here at the moment. I will try to get any statistics on freediving injuries requiring recompression etc and publish them here.

Thanks again guys... interesting stuff

 

[Bill]

Luke

Kirk Krack of Performance Freediving opened a thread about a DCS hit while using a scooter.

".......................................
Example with Dr. Batles tables;

If you attempted a freedive to 21 meters for 1:30 (spearfishing) you
should wait on the surface 2:20 before your next dive.

If your next dive was to 36m for 1:30 (intermediate level competitor) your
surface interval (SI) should be 3:27.

A dive to 69m for 2:20 which is typical of an expert competitive freediver
the surface interval before any other freedive is 9:13.

He developed a simple rule of thumb; If the depth of your freedive was <
25 meters then your SI should be twice your total dive time.

If your depth was > 25 meters then your SI should be a minimum 8
minutes.

His article/paper is called "The Attitude a Breath Hold Diver Should Take to
Avoid Arterial Gas Embolism". He's Associate prefessor of University of
Balearic Islands (Spain) and Chairman of Medisub, Hyperbaric Research
Institute."

Aloha
Bill

 

[cdavis]

Polorutz,

Thanks for the heads up on descent rates; I'm approaching the depth where I have trouble equalizing. Descent rate feels much faster than 1.2 m/s in the first 20 m or so, but I've not actually timed it. On our rig, the rope streams out behind the boat as it drifts, helpful in keeping it out of the way, but it feels like the descent rate slows down as I approach 30 meters, I had assumed from the rope drag. I had considered that a negative, maybe not. Has anybody else had this experiance? Also, variable allows me to relax more than cw. It seems to make it easier for my lungs to contract. Again, does this seem right??

Connor

 

[Adrian]

I relax more with variable, just close the eyes and keep compensating. I got down to 34 meters before being unable to compensate while with CW I was getting stuck around 29-30 meters. I need to practice the mouth fill!

Adrian

 

[McGough]

Tipple,

Getting right into it.... I like it...
Got some unit status happening as well over there. Not bad for you at all mate.
I'm off for some Great Barrier Reef Freediving this weekend. Maybe catch a feed for two out there.

Enjoy old sons.

 

[Crypple]

McGough Mate!

Good to see you into it! Me and Sammy D will be poppin all over San Diego soon enough... come over for some cold water action mate!

Connor, Check out the reply I posted on the previous page about the rig we use with pulleys, we've managed to reduce the drag to near 0 using the right pulley/rope combination. Upon reaching depth we actually speed up with this rig! Descent speed can then be controlled with body flaring.

ALL: Incidentaly DAN does not have any hard stats on freediving DCS.

 

[cdavis]

Crypple,

What diameter pulleys are you using?

Connor