The RIGHT thing to do in a blackout.

[Frosty]

dale C--hey look I'm just some twit who has logged less than 50 dives so I don't claim to be an expert.
At a number of feet (90 named for convenience) there is a thermocline.I can't explain why or how but there is a distinct and clear line where vis is actually as you picture above the line and honestly it looks like the bottom of the lake below the line.Dip a fin below that line and theres like an explosion of thick silt to look at but its still very "wet". If you keep finning like that your buddy is in darkness even if they are a couple of feet above you. The more you move the more it muddies up and the higher and wider it spreads. I apologise if I'm not explaining it well

 

[DaleC]

Don't take it personal, I just don't see that happening. But if it did, just swim a few feet higher. Someone should notice going from good vis to zero vis and stop to communicate with their buddy about it if it is unanticipated. If a leader transitions like that and never looks back you simply have a bad buddy that's all.

Low vis diving isn't really that hard but it does take a team that works together. If the team doesn't do that then they should not enter low/no vis conditions. That isn't meant to sound flippant, it's really just that simple. Coming up with alternate plans will not compensate for a failure there.

As I said, when team diving in low vis I prefer side by side formation far enough apart to maintain visual contact of a sort (that may mean touch contact) and lights for communication. All of this should be sorted out ahead of time. I've done hour long dives like this without losing contact.

If you find yourself with a buddy that dives "follow the leader" style, doesn't look back regularily and transitions without checking on your whereabouts you can try to signal them (if possible) or just abort the dive and give them sh_t on the surface (when and if they realise you're gone). That may sound harsh but you really don't owe it to anybody to continue a dive depending on the buddy system if you feel the "buddy" follows no system.

I'm using the general "you" of course and not the specific, as I have no idea how you dive personally.

 

[ianr33]

If you keep finning like that your buddy is in darkness even if they are a couple of feet above you. The more you move the more it muddies up and the higher and wider it spreads. I apologise if I'm not explaining it well

How are you kicking? Frog kick (or modified frog ) is the only way to go above a silty bottom.

 

[paulw]

I would do the following 4 things: Stop. Breathe. Think. Act.

1. Stop all movement.

2. I'm still breathing and I had plenty of gas when this happened so I have a lot of time.

3. Should I shoot a bag? No way!!! I don't practice this skill with my eyes closed and why should I add entanglement and runaway ascent risk to this equation? I was at 90 ft and bottom is at 180 so I'm not going to use the bottom for reference. Maybe I can ascend above the silt cloud. I bet it doesn't go all the way to the surface, surely not above the first thermocline. I don't want to kick and stir up more crap so I have to become positive but be careful of run-away ascent. That's the plan. Hopefully the silt clears while I am thinking but if not...

4. I become slightly positive by expanding my chest or even adding a small burst of air to my BC if necessary. If I can't see my computer even when backlit against my mask I listen to what my ears (and the pressure in my mask) tell me about how fast I'm ascending. Good. Starting to see some bubbles now. Slow down. I'm above the silt cloud. I re-establish neutral buoyancy and look for signs of my buddy for one minute and then make a normal ascent. If my buddy stays missing for too long I notify emergency services of the missing diver.

Afterwards, I would try to apply my new experience and not dive 90 feet at this location without being prepared for zero vis as a possibility.

100% Agree, I have experienced just that and if you stop, breathe and think you will realize you can ascend just a little and maybe have some vis again to be able to see your gauges and maybe your buddy. You did shoot a heading on your compass before you dove didn't you? If so you know where shore is. I wouldn't shoot a SMB from there, you cant see and might get tangled in the line where it pulls you up or it gets tangled in tree limbs and so on. In the lake I dive I have seen a silt "cloud" hanging just at the thermocline and as you drop through it the vis was so bad you couldn't see your gauges but if you keep dropping it clears up very nicely but you should always have made a plan so you and your buddy understand how and what you will do if something happens. Always remember, anytime you get disturbed for any reason just STOP, breathe and think and after you are calm and your head is clear ACT.

 

[TSandM]

I have never been through a big thermocline, but I do understand that they can behave like haloclines. If you go through a halocline, you disturb the interface, and the resultant mixing instantly reduces the viz. It's like diving in salad oil. But it's not zero viz -- you can see some very distorted shapes and colors, and you can certainly see your gauges. If you can see your gauges, life is pretty easy -- you either continue downward until you are fully in the next water layer, or you go back up until you reach clear water. (Or, in the case of the caves where I dive, you okay the line and follow the guy in front of you, until you get to a part of the cave where your team doesn't have to swim single file in the boundary layer.)

True zero viz, where you can't see your gauges, really requires a heavy layer of particulates in the water. The way to deal with that kind of zero viz is to GET OUT OF IT . . . If you are descending in open water, and get into that kind of silt, ascend and get out of the mess. If you have disturbed the bottom in a localized area, swim away from it; we have this issue commonly in Puget Sound, where we have very silty sea floors and a lot of novice divers who don't know how to avoid kicking it up.

 

[ianr33]

Our local hole (Travis) sometimes has genuine zero viz at the thermocline due to a white milky layer. Not sure of the exact chemistry but pretty sure it's related to sulfides in the cold ,anoxic,lower layer being oxidized to sulfate where it meets the warm,oxygen richer upper layer. The sulfate then precipitates out as calcium sulfate .

On one memorable dive we were ascending from maybe 130 feet and met viz so bad that even with an HID pressed to my mask I could not read my gauges. Decided the best course of action was to finger walk up the silt slope. After ascending a few feet the viz returned. Strange thing was that where we descended the viz had never gotten really bad.

 

[Jax]

Ha! Until you've dived Lake Pleasant . . . . (NE of Phoenix, AZ) . . .

Lake Pleasant has what seems like a series of cloud layers . . . you can descend and lose vis like that! (snap!) Sometimes, you keep descending and you will pick up a very clear vis underneath the layer. Sometimes, it's no better.

I wear a Glo-Toob (so's you can find the body. ) When my instructor and I descended past 50FFW once, I lost him even though he was in arm's reach, and he could just barely see my Glo-Toob. As the area had a silt bottom at 60-65', we didn't bother to try to go down.

However, that same weekend, someone reported 40' vis under the 50-60' cloud, in another part of the lake.

You just have to know your area and have a dive plan.

 

[Buoyant1]

I would do the following 4 things: Stop. Breathe. Think. Act.

1. Stop all movement.

2. I'm still breathing and I had plenty of gas when this happened so I have a lot of time.

3. Should I shoot a bag? No way!!! I don't practice this skill with my eyes closed and why should I add entanglement and runaway ascent risk to this equation? I was at 90 ft and bottom is at 180 so I'm not going to use the bottom for reference. Maybe I can ascend above the silt cloud. I bet it doesn't go all the way to the surface, surely not above the first thermocline. I don't want to kick and stir up more crap so I have to become positive but be careful of run-away ascent. That's the plan. Hopefully the silt clears while I am thinking but if not...

4. I become slightly positive by expanding my chest or even adding a small burst of air to my BC if necessary. If I can't see my computer even when backlit against my mask I listen to what my ears (and the pressure in my mask) tell me about how fast I'm ascending. Good. Starting to see some bubbles now. Slow down. I'm above the silt cloud. I re-establish neutral buoyancy and look for signs of my buddy for one minute and then make a normal ascent. If my buddy stays missing for too long I notify emergency services of the missing diver.

Afterwards, I would try to apply my new experience and not dive 90 feet at this location without being prepared for zero vis as a possibility.

I agree! Stop, breathe and think were my first thoughts when I read the scenario...and I stopped at this post!

I had a mask failure at 90+ this past Wednesday night, and those three words kept me from freaking out. Diving blind no matter HOW it happens isn't fun, but you need to solve the problem, and get out of the problem. Once I realized that a quick adjustment wasn't going to fix it, I made sure my buddy knew I had a problem, and we moved forward and upward until it lessened. The problem didn't completely resolve, so we did a safety stop, and finished the dive. Thankfully the surface swim wasn't bad.

We have the same silty crud at the bottom of our quarry as well, and not stirring things up was another thing on my mind as got out of my problem.

 

[Togalive]

Besides all the great points outlined by other members, one thing I think a bit funny is that people often forget that if you really lose all sense of direction and you need to establish which way is up or down, just look (or feel with your hand) where your bubbles are going!

Also, this never would have happened if the divers had planned their dive and dived their plan correctly and responsibly.

 

[Max Speed]

If the viz is that bad, as in you can't see your light when it's in your own hand, I like to use a $5 dog leash to stay connected with my buddy. In a pinch you can hang on to your buddy's octo or simply stay within hand touch distance. (Hint: If you're hanging onto their octo in bad viz you can steal their air too....)