Safety system for 60m buoy diving.

[timm]

Hey

A few of us are looking at doing some CW diving from a buoy, and I was thinking through a safety procedure taking into account there is probably going to be 3/4 of us and just a buoy and rope.

I have had a chat with friends and come up with a couple of ideas, but any advice or expereince would be great.

We are looking at a 60m rope, hopefully in 25 m vis water and max dive times of 2m 30s. Plan is for safety diver to be meeting the diver at 25m. If the safety diver cant see the diver by 2.30, he signals to the surface who starts the procedure, now we have come up 1 of 2 options here.

1. We ony have 2kg on the line as we only need to keep it straight for CW, we have 10kg on the other end of the line sitting in the boy, rope runs through a couple of karabiners. We chuck the 10kg weight in and then can start pulling the diver and rope up, using the counter balance to even out the weight somewhat.

2. Again with a light 2kg bottom weight. Surface diver dives down to 30m, attaches and opens an FHOF (small tank and lift balloon) to the rope bringing the diver to 30m. The safety diver has resurfaced and prepared breathig up for a 30m rescue dive.

Option 3 from JM
3. Same set up as 1, 2kg, with a 10kg counterbalance. Surface diver realses the 10kg counter, and dives with it to 30m, meets the diver, and does a rescue using the FHOF to surface from 30m. (like the thinking resue no limits)

Any thoughts, opinions, alternatives would be great.

Tim

[samdive]

I think option 2 would be best. I don't think 10kg would really be enough to get things going, especially with the diver also trying to go down on it bearing in mind the buoyancy of the suit and I guess this is going to be in te red sea so the divers will be pretty buoyant.

However - attaching and firing an FHOF can be fairly slow and fiddly, particularly under stress so reliance on FHOF is not ideal if the person firing it is breath holding.

I'll keep thinking

[timm]

I was initally going with the FHOF aswell, but after talking it through the counter balance seemed the less complicated.

I am working on worst case scenario, as in diver hasnt appeared in 3 mins, so you gotta do something.

I need to test it, but was hoping the 8K difference would make pulling the rope up manageable between 2 people. Probably pull it up by pulling underwater as we have assisting in getting the bottom plate up at Salt Free.

Was thinkning if I could get the diver to the surface anything under 2 minutes from 60m, this would be good / successful and much quicker than the FHOF solution, as the FHOF dive and rescue dive would be more than 2 mins.

Tim

[laminar]

Hey Tim,

Further to what Sam said I wouldn't count on a safety free diver diving to 30m to operate an FHOF solution to raise the diver from depth. That's a pretty stressful thing to do, no matter the skill or ability of the diver who is asked to make the dive. That a dive deep enough to cause complications if the safety diver is freaked out, nervous, scared or afraid of what might happen if he or she doesn't succeed.

Pete

[OceanMan]

Quite agree with Laminar. I would definetly not go for 2. 30m twice is a lot in a safety situation.
I would go for 1 : the simpler the better.

[turtle]

Hi Tim,

It all sounds really well thought out. I would suggest going with the simplest option - if you have 2 kgs bottom weight, and a hefty buoy to lie over, you can pull up someone very fast hooked on to a 'biner. If you are diving in a group of 3, this is quite efficient. The biggest moment of risk for safety diving seems to be the time it takes to a, realise something is/has gone wrong then b,to act on that. Having relatively complicated safety plans that take an effort to set into motion just increases this risky period.

I don't know of any buoy-based counterweight systems that have ever functioned really satisfactorily enough to be really reliable and effective or worth the effort but i'm sure there must be some way of doing it properly that's not been done yet.

Anyway, those are my uninformed opinions. I'll be really interested to see what you end up doing mate.

Fred

[timm]

Yep simplest seems the best, pulling them up seems the way forward, I want to try with some sort of counter weight to see if it helps. I know its not going to pull them up by itself but I reckon an extra 8Kg would ease the pull and would make some difference.

The buoy is on its way so I will be having a play and let you know.(Sam you will probabaly be seeing the results, if thats cool, you can even be victim no.1 if you trust me?)

My only first thought / issue with this solution is the problem with knocking the diver out with the 10kg counter balance weight when it descends. Anyone got any ideas on how to make this a bit safer.

I was thinking of wrapping the weight in something spongy, dont think bubble wrap will help the speedy descnt though.

Tim

[BennyB]

Tim the Canadian team at the Worlds had a counterbalance system based on two floats about 6-8 feet apart and attached with a metal pole of some type. I only saw it once when they walked past on the beach but you could probably get in touch with them to get the specifics.

Something as simple as two floats with a broomstick separating them could potentially work though you might want a bit more distance between them to ensure the unconscious diver doesn't receive a rescue clonk on the head on the way back up.

Cheers,
Ben

[fcallagy]

Could you pass the line through the pipe with some sort of protection to stop it catching fraying a ninety degree bend on each end pointing downwards so the rope is sliding through it. Bouyed at each end.
Regards Feargus.

[timm]

Yeah I remember seeing them walking it along the beach.

I think it might have even had the rope descending down the middle of the pole between the 2 buoys. A very nice set up. But I am trying to keep equipement to a minimum for travelling, 1 buoy 1 rope, they had a load of stuff.

Maybe some sort of 1m or so bar that sits ontop of the float and just give that extra 50cm seperation between lines, hmmmm... would that be enough.

[AltSaint]

Shame it's not practical to have 60 metres of lightweight high pressure hose, otherwise you could inject compressed air from the surface down into a liftbag on the plate.

Alun G had a lift method of sorts that he used at Dorothea, but I don't think he posts here any more. Steve Millard knows how it all worked, so it might be worth contacting him ( his email is on some of the team posts ).

[AltSaint]

Something slightly more sensible than my first suggestion goes back to your option 1. It means you must have a freediver confident in doing deepwater rescues, to 33 metres ( and who doesn't get involved in the rope pulling! ). When setting everything up, once you have let out 32 metres of rope, you attach something like a climbing ascender to the rope ( to stop the rope moving past the float shackle in the reverse direction ).

If you have to deploy your 10Kg counterweight, then the counterweight shouldn't be able to make contact with the victim, assuming he is dangling down from the plate.

The safety diver should be able to descend at the same rate as the descending counterweight, and if for any reason the victim is further up the line, then move either the weights or the victim.

It's not completely ideal, but then neither is any counterweight system.

[tecdave]

Alun's system was very effective in getting the diver to the surface but was a pain to lift the weight to reset it.(hopefully it doesn't need to be reset!) we used a 2m metal bar with 2 large buoys on the end, 2 pulleys on the end of the bar and a sailing rope clutch set on the middle of the bar. The rope ran through the pulleys and the rope clutch and the weight was held to the buoy with a quick release shackle. if it needed to be deployed, you opened the clutch and pulled the shackle toggle. this sent the 20kg down 2m away from the diver coming up. The pulleys reduced friction and increased speed you then use the clutch to stop the rope when the diver nears the surface. Hope you can follow this!!!!!

I will try and dig a pic of it out and post later.

Dave

[timm]

Dave a pic would be great if you can find. Although it might not be an option for travelling, weight allowance and 2m metal pole should never be used in the same sentence. But would be great for some UK diving so if you can find please post.

Mark I see where your coming from I think, but wouldnt the climbing ascender get in the way of the lanyard when diving, or did I get confused....

On the same subject concept though, if the divers are comforteable to 35m, then why doesnt the counter weight operator dive with the counter weight down to 30m they will then make sure the weight doesnt hit as they meet the diver(we can still add some padding to the weight), meanwhile the safety diver has resurfaced and started hauling rope. Counter weight rider can safety rescue the diver or surface and pull rope depending on them.

[laminar]

I had an idea for a simple and effective safety system based on a single buoy idea last year but never had the time to test it out. Perhaps it might be a solution:

The concept is that you have a wheel or drum with a circumference of one metre with a crank handle on each side. The rope spools around the drum and the drum is fixed just above the water with buoys (more like boat bumpers) on either side. I envision a thin light aluminum frame to hold it all together. It wouldn't very large at all, no larger than a large buoy. In fact, you could also use an inner tube. The drum itself could be hollow as much as possible so that it is easy to turn. No more than 2-3 kg of bottom weight would be used. It's not for competition, just for training.

Anyway, clutches or carabiners could be used to stop and release the rope. But the concept would be simple. One (or in a real emergency, two) attendants could turn the crank(s) to lift the line. Given the circumference of 1m, the line would likely be able to be lifted at more than 1 m/s. You could choose to make the drum have a larger circumference.

An additional safety protocol is to decide on a timing for the dive (ie. the freediver's expected dive time +10 seconds) and then start pulling up the line at 1 m/s. Then you are sure that if a retrieval is necessary, the freediver won't sink deeper before getting pulled up. The line could be reeled in on every single dive. It would be some work (although I'm sure you could figure out some mechanical advantage with the crank) and it would be best to have a dedicated attendant and safety freediver to make it safer.

I'm sorry I don't have a drawing of it. I'll try to get one up.

Pete