38 replies to this topic

[shadragon]

Had an experience on the weekend that I wanted to share. It was my first true deco dive. I was on doubles and a dive plan floor of 130 feet with two other divers. We were on a lionfish hunt along with another pair of rebreather divers who were going deeper still.

We deployed off the boat fine and my max depth was 129. The CCR divers headed off and our group of three went our own way. We kicked along for a while in the 115-120 foot range then slowly came up as we went along to the 100 foot level. At this point, I was in deco on my computer. The dive leader signalled for me to deploy my 100 pound lift bag as we had planned. Now, having had a scallop license for many years, sending a liftbag up is old hat to me and as the others were not as experienced they nominated me to do it.

I unrolled the bag and connected it to the reel. As I was filling the bag with my alt air source, the fabric on the bag covered my right arm where my slate was and I could not see it. Just as the bag took off I saw the loose line had wrapped around and under the slate. I reached for it and while doing so turned my wrist slightly on the hand holding the reel. It turned just enough that the reel line coming off the roller wrapped around the reel shaft. With the up-force of the bag the line jerked hard, pulled on the slate bungee and up I went...

I let go of the reel and tried to pull the line away from the slate, but was unable to get a purchase with my fingers. The higher I went, the faster I rose. I have a knife on the inside of my calf, but instead I was able to grab the secondary folding knife on my harness. It could be opened one handed with a thumb and I was able to cut the line just above the slate. The bag and reel roared up to the surface. At that point I was still going up due to the expanding air in my wing so I dumped it and eventually stopped ascending at 47 feet. I descended as quick as I could to get back to the group.

Once back with the others the second diver tried deploying his bag. It was an older model, went up about 20 feet flipped over, lost its air and sank. The last diver nervously deployed his his and was able to send up his bag without problem. The reel jammed as we were ascending and he had to wrap the line around the entire harness, but it worked. We did a very slow ascent, fulfilled our deco commitments and surfaced. Luckily the chase boat had recovered my lift-bag and reel.

If I had been forced to use my calf knife I am convinced I would have hit the surface before I could get to it.

Backup knives... Do you have one? Can you use it one handed?

[georoc01]

Had an experience on the weekend that I wanted to share. It was my first true deco dive. I was on doubles and a dive plan floor of 130 feet with two other divers. We were on a lionfish hunt along with another pair of rebreather divers who were going deeper still.

We deployed off the boat fine and my max depth was 129. The CCR divers headed off and our group of three went our own way. We kicked along for a while in the 115-120 foot range then slowly came up as we went along to the 100 foot level. At this point, I was in deco on my computer. The dive leader signalled for me to deploy my 100 pound lift bag as we had planned. Now, having had a scallop license for many years, sending a liftbag up is old hat to me and as the others were not as experienced they nominated me to do it.

I unrolled the bag and connected it to the reel. As I was filling the bag with my alt air source, the fabric on the bag covered my right arm where my slate was and I could not see it. Just as the bag took off I saw the loose line had wrapped around and under the slate. I reached for it and while doing so turned my wrist slightly on the hand holding the reel. It turned just enough that the reel line coming off the roller wrapped around the reel shaft. With the up-force of the bag the line jerked hard, pulled on the slate bungee and up I went...

I let go of the reel and tried to pull the line away from the slate, but was unable to get a purchase with my fingers. The higher I went, the faster I rose. I have a knife on the inside of my calf, but instead I was able to grab the secondary folding knife on my harness. It could be opened one handed with a thumb and I was able to cut the line just above the slate. The bag and reel roared up to the surface. At that point I was still going up due to the expanding air in my wing so I dumped it and eventually stopped ascending at 47 feet. I descended as quick as I could to get back to the group.

Once back with the others the second diver tried deploying his bag. It was an older model, went up about 20 feet flipped over, lost its air and sank. The last diver nervously deployed his his and was able to send up his bag without problem. The reel jammed as we were ascending and he had to wrap the line around the entire harness, but it worked. We did a very slow ascent, fulfilled our deco commitments and surfaced. Luckily the chase boat had recovered my lift-bag and reel.

If I had been forced to use my calf knife I am convinced I would have hit the surface before I could get to it.

Backup knives... Do you have one? Can you use it one handed?

No I haven't carried a backup knife, but I do have both a knife and a line cutter. Could I deploy it one handed? Maybe, never tried.

That said, you might want to look at how you are filling that lift bag. During my tech class we spend lots of time under water working on deploying SMBs and lift bags, and the only way my instructor allowed was to fill using the exhaust of off your primary reg with the line taught to the reel in front of you. I don't get as much air in, but at the depth you were deploying at, I don't think its as much an issue if say you were deploying at 20 feet. The reasons he gave was to avoid situations like the one you described above.

[duganalexzander]

I have a Z-knife attached to my wrist slate, and a good old fashioned serrated blade attached at my hip. I can get to either one with one hand, but I can't get the Z-knife with my left hand (as its up by my left bicep).

Perhaps you should rethink the location of your calf-knife. As you said, it would take to long to get to it if you needed it quick. Are there any advantages to keeping it there?

-Will

[Jerrymxz]

I have a small Akona knife high on my left harness deployable with one hand. my backup is a Titanium Z Type line cutter mounted just beside the waist buckle on my harness accessible by either hand. Both are kept SHARP.

[WreckWench]

Great discussion...
Great topic to think about...
Great example as to why we need several back up options when all heck hits the fan....

[peterbj7]

Sounds a rather nasty experience. When I did a similar thing many years ago it put me in the chamber.

BUT, I have never understood this:-

The dive leader signalled for me to deploy my 100 pound lift bag

I have lift bags which I use when I want to lift something. They are of a design that cannot spill air unless overfilled for the depth they're at. I have owned and used American lift bags (DiveRite, OMS, etc) that were little more than an upturned balloon and I regard them as potential death traps. I would NEVER use one voluntarily. The ones I use have a very long and narrow neck and will stay inflated even in very rough seas - vital if holding something heavy.

Nor would I deploy a lift bag unless I wanted to lift something. If what I want is an ascent platform and a marker to show people on the surface where I am I use a DSMB. The best I have personally come across are made by AP Valves in England, but they're also available made in the USA - DAN market their own. These are not "safety suasages" though they do bear a superficial resemblance to one. They are substantially made, pretty long, have an inflated diameter of about 8", and give a lot of lift. They have a no-purge valve so they cannot auto-deflate, and an over-pressure valve. In Britain they are universally used for ascending by all other than beginner divers.

I use several different types of reel, depending on the circumstances. For caving I use an open spool, which necessitates considerable care in handling to ensure the loops of line don't fall off and create the sort of tangle you described. For a lift bag I may use the same trype of spool that I use for a DSMB, which is an enclosed ratchet spool of around 130ft (mine is the "Buddy Reel", made by AP Valves). This cannot tangle unless used absolutely inanely, nor if given a modicum of maintenance can it jam. It is absolutely perfect for the function. In England a very popular reel for a DSMB is an open ratchet reel - I've used these many times and used to own some, but I don't like the open reel because line can spill off.

I have seen people trying to deploy a DSMB or lift bag using an open finger spool. Almost invariably they have problems, sometimes terminal (they have to jettison the reel). These reels are not suitable for this application. I have also seen many people trying to deploy and use a DSMB with a non-ratcheting friction-lock reel. OK during deployment, but quite unsatisfactory once deployed - you want to be able to hang off the line, and a friction lock will simply slip. Only a ratchet lock will work.

Out here in Belize I dive with my orange DSMB permanently attached to the line of the reel as one unit. Makes deployment simplicity itself. I can and have deployed it whilst holdiing two divers, air sharing via octopus with one and buddy-breathing with the other. You try doing that with an open reel, or indeed with a US-style lift bag.

I did a lot of my training with US technical instructors, and to a man they didn't seem to understand what a DSMB was and regarded a liftbag (open style) as the answer to everything. I was by then very familiar with DSMBs and refused to use the wrong tool for the job. One instructor at least was convinced by my arguments/demonstrations.

I said I deploy my orange DSMB - that is for a normal ascent. In an emergency in Europe I will deploy a yellow one, which announces to the waiting boat immediately it surfaces that I have a problem and need help. A very useful colour-coding system that sadly is too often ignored over here.

On a serious dive in Britain I'll carry two DSMBs, one orange, one yellow. The orange one will have a reel permanently attached; the yellow one will merely have a suicide clip at the bottom that fits over the deployed line if/when I have an emergency. At the top of the yellow DSMB I have a small slate on which I can write what the nature of the emergency is, eg. what gas I'm running short of. In addition I'll carry two lift bags, each of 50-100kg, in case I find something really attractive and portable.

Of course, deploying a lift bag can use a lot of gas, especially if it's lifting something heavy. I recall a friend who found a pristine brass porthole lying on the bottom at around 80mtr (270ft). He attached one lift bag and inflated it with his bottom gas (a trimix) - nothing. He attached his second lift bag (we always carry two each) - the same. He attached and deployed his orange DSMB - still nothing, though the porthole was clearly getting loose. He was in process of attaching his yellow DSMB when his bottom gas ran out. There was no-one around, so he left everything on the bottom and bolted, stopping only when he was shallow enough to use his travel mix (35% nitrox). He had missed lots of stops and his computer let him know in no uncertain fashion, and he was in process of trying to catch up with these when his travel mix ran out. He again bolted, until he was able to start breathing his 80%. He now had no DSMB and no means of signalling the surface, so he pretty well drained that tank and surfaced with 30-40 minutes of undischarged deco. No-one else knew any of this until we surfaced from our respective dives, around an hour later, when we saw him lying on the deck breathing pure oxygen. Astonishingly he got away with it. He later transferred to a CCR but had the good sense to quit diving before he killed himself.


I forgot - knives. I don't carry any sort of knife on normal dives here (Belize) as there's nothing to tangle with. When I am carrying a knife I carry two, diagonally opposite of the abdomen area. Typically one will be by the corrugated hose, the other near the waist strap on the righthand side. These knives are small and folding, with blades around 3" long. The blades are corrugated, concave, and made of carbon steel so they're extremely sharp. They will rust readily so I have to remove and clean them after a dive, and I usually spread a thin film of Vaseline on the blades. I don't use any sort of knife attached to a leg, as I have seen several instances of such a knife being the cause of an entanglement. In any case, once you're tangled it's often impossible to reach such a knife. That said, in quite a few dives I have rarely been entangled, and when I have been I have always found another way to escape (typically removing gear, taking off the tangling line and putting the gear back on again). I have never used a knife to cut something underwater in an emergency.

Edited by peterbj7, 15 August 2011 - 06:17 PM.

[scubaski]

I use 1 - 3" sharp point combo blade located on my right shoulder harness about nipple level. Either hand can unlock and use blade. My knife is TETHERED to scabord by a coiled plastic leash that can be extended easily about 3' or cut by said knife to hand off if needed. I may lose or drop my 1 knife when needed BUT it will only be a few inches from my right side chest even on a wall dive in GCM.

My diving is all recreational single tank in the warm carib, often drift diving. Always carry SMB about 6"W x 5'L, orally or regulator filled with a over expansion valve. SMB is attached to a 3" finger reel with about 80' of mason line. A couple of tricks I learned from Peter was to fold the SMB until the last bit where you roll it up and when inflating put a lttle shot of air into it to float it upright before the main blast of gas.

[Landlocked Dive Nut]

Dive knives are expensive (the good ones are) and I have not yet chosen one to invest in. First because I don't want to spend money on a knife that I won't be happy with, but mainly because I have not determined the best place to attach it to my gear based on my own preferences & gear configuration. I would prefer strapping it to my upper right thigh, but all I've found so far are calf straps and trust me, I need a bigger strap than that for my thigh! If anybody has seen thigh straps online that will work with a hard knife case, let me know.

On the issue of finger spools, they do have certain issues that, unless you practice using the spool, can be problematic. I was taught during my Deep Diving class how to deploy lift bags and DSMB's, including the trick of putting a bit of air in the lift bag or DSMB when you start the deployment - just enough to give it enough lift to get out of your way & hover nearby while you finish your preparations to deploy. For the DSMB, I do use a finger spool that is always attached to the DSMB. I found while practicing deploying that if the spool is dropped onto my photo stick and with one finger holding the line, it's much easier for me during preparation and during actual deployment. As the blast of gas is introduced, I can keep the photo stick angled upwards to keep the spool in place, and once the blast is finished I can hold both ends of the photo stick in front of me while the DSMB journeys to the surface (and I don't get a finger-spool-burn!). Once it's stable on the surface, I remove the spool from the photo stick, clip my stick to my BC and wrap the spool as I ascend.

I see Peter's point about deployment if you're holding onto a buddy who can't help, though. I need to consider in advance what I would do if that scenario ever presents itself.

[scubaski]

Oh!! So your going to sport one of those Crocodile Dundee knifes on your ankle or thigh!!! IMO placement should be in the torso area chest to waist, either hand able to deploy.

[Landlocked Dive Nut]

Oh!! So your going to sport one of those Crocodile Dundee knifes on your ankle or thigh!!! IMO placement should be in the torso area chest to waist, either hand able to deploy.

It's not going to be a Crocodile Dundee knife! That's overkill.

I tried carrying a small knife on my BCD (I tried 2 separate places) and hated it there. I let the ex have it. I want whichever tool I end up buying strapped high up on my right thigh...easily accessible for me, and not in the way of anything else. Since I'm decidedly right-hand dominant, the tool must be mainly accessible to my right hand. And believe it or not, I can reach that area with my left if I absolutely have to, even if I feel totally inept using my left hand for much more than typing! I think I'd like to find a combo tool....a blade and shears combined, perhaps?

[peterbj7]

Dive knives are expensive (the good ones are)

I now use very cheap knives from Trident, and they are probably the best knives I've ever used. Extremely sharp, retain their sharpness, and shaped so that you can cut any line or rope single-handed. The only thing to remember is that being carbon steel they will rust if not cleaned and protected. Of course as they're very light they can't be used as a hammer.

For anyone wanting to keep a knife anywhere on their leg I can only suggest you try to reach and use it when you have deliberately tangled yourself up.

[shadragon]

BUT, I have never understood this:-

The dive leader signalled for me to deploy my 100 pound lift bag

The use of lift bags is a convention we use locally. We reserve the SMB's (Surface Marker Buoy or 'Safety Sausage' typically red / orange) to signal a problem to the dive boat. If someone gets separated, or the group has an issue we deploy the red sausage. When diving several groups in the water at the same time, it is a fast way to get the attention of the dive boat and the safety divers can be ready to assist. The sausage I use has a deflate valve for controlling the amount of air inside. The yellow lift bag tells the boat where the group is and that we are within the briefed dive plan. An SMB or lift bag are deployed in exactly the same way. The SMB only has 25 pounds of lift versus the 50 or 100 of a bag, but that is still enough lift to give you issues.

My calf knife has a 5" blade, is titanium and very sharp with serrated edge on one side. Will cut through a 3" thick mooring hawser easily. It is on my leg for practicality, it is too large to put anywhere else. I have used it on a few local wrecks to remove fishing line / rope and improve safety. My backup is a 3" titanium folding knife with fishing line cutter I just bought and is mounted on my waist webbing. Last, I also carry a pair of shears for cutting through webbing.

What I carry works for me and I am not preaching to convert people. I just want you to think about what you have on your current rig and ask yourself, will it work for you in the same situation? It has certainly forced me to re-examine my current set-up while imagining one arm or the other not being usable.

Cheers all.

[peterbj7]

My calf knife has a 5" blade, is titanium and very sharp with serrated edge on one side. Will cut through a 3" thick mooring hawser easily

What brand/model is this? I have several titanium knives but although they're pretty to look at I find they are too blunt to cut anything and of course they can't be sharpened, so I never take them diving. But I'd like to believe there are decent titanium knives out there somewhere. Any one of my Trident carbon steel knives, weighing an ounce or so if that, will cut a sheet of paper under its own weight, and when opened has to be handled rather carefully.

But in reality I have never in 6k+ dives had cause to use a knife in anger underwater. I have been entangled, but it was always easier just to take the offending gear off, disentangle and continue. You need to see what you're cutting, or you can end up cutting something you didn't intend to and getting yourself into far more serious (not to say costly) trouble.

[duganalexzander]

The knife I use is here: http://northeastscub.../prod_2192.html

I like it because its sharp, serrated, stainless steel, and most importantly: it costs $10.

Personally, I like 'dirt cheap' knives best. If you drop a $10 knife 30 feet its no big deal, but if you drop the $100 dollar knife 30 feet, chances are you'll want to go get it.

[shadragon]

My calf knife has a 5" blade, is titanium and very sharp with serrated edge on one side. Will cut through a 3" thick mooring hawser easily

What brand/model is this?

Underwater Kinetics - Blue Tang HydraAlloy. Who says you cannot sharpen titanium knives? You need a good quality whetstone and it takes longer, but certainly can be done.