What do you look for in students to tell if they are ready for AN/DP?

[Ulfhedinn]

You don't need to fill the SMB all the way when you're shooting it from depth. When I'm shooting from 100'+ (30m for you guys and your fancy metric system), I rarely fill it more than a third of the way, the magic of Boyle's law does the rest. You can put hash marks on your SMB that will help with making sure it's full at the surface. I have hash marks for 33', 66', 99' on mine - fill to the hash mark depending on the depth you're at and viola. I'll be happy to grab a photo of them sometime in the near future and post it here.

I agree with letting it bob and stay neutrally buoyant yourself. You shouldn't need to touch the reel to maintain your depth. The nice thing is you'll never notice the depth changes even in rough seas because you will rise and drop with the peaks/troughs if you're properly neutral.

The SMB needs to be standing up when you're drifting in a current or a boat tracking multiple groups of divers may never find you in a light chop. The weight of the reel will help keep the SMB up. A slight tug does wonders too, but you should not be using the reel to keep yourself neutral.

No visual references in this case means shorelines, anchor lines, etc that can give you an idea of depth / location.

Pic would be cool and TY

 

[Tracy]

Yeah, that is my spider web, I get asked a lot if it is a shark cage. My first thought is always "Yes, we sink the whole boat and look at Great Lakes sharks."

Looks like there's some great hand-holds on that boat. Really useful when the boat's lurching around in the sea.


A British summer - calm but misty. A week day and only three of us diving. Normally up to 12 on that boat.

 

[rob.mwpropane]

Yeah, that is my spider web, I get asked a lot if it is a shark cage. My first thought is always "Yes, we sink the whole boat and look at Great Lakes sharks."

I choose to believe.

 

[jtsfour]

You don't need to fill the SMB all the way when you're shooting it from depth. When I'm shooting from 100'+ (30m for you guys and your fancy metric system), I rarely fill it more than a third of the way, the magic of Boyle's law does the rest. You can put hash marks on your SMB that will help with making sure it's full at the surface. I have hash marks for 33', 66', 99' on mine - fill to the hash mark depending on the depth you're at and viola. I'll be happy to grab a photo of them sometime in the near future and post it here.

I agree with letting it bob and stay neutrally buoyant yourself. You shouldn't need to touch the reel to maintain your depth. The nice thing is you'll never notice the depth changes even in rough seas because you will rise and drop with the peaks/troughs if you're properly neutral.

The SMB needs to be standing up when you're drifting in a current or a boat tracking multiple groups of divers may never find you in a light chop. The weight of the reel will help keep the SMB up. A slight tug does wonders too, but you should not be using the reel to keep yourself neutral.

No visual references in this case means shorelines, anchor lines, etc that can give you an idea of depth / location.

When practicing SMB shooting I am typically in shallow water. What is the standard way to launch them? I am assuming to fill one 1/2 or 1/3 of the way you would need to be quite negative...

I've seen people use regulator exhaust out of the one they are breathing.

I've seen people purge their backup reg into it.

I've seen people use Drysuit/Inflator hoses.

What is most common? I've personally tried all 3 at least once. I didn't like how violent the powered inflation was.

Another question. How universal is the rule that a yellow SMB means distress? The SMB I have been carrying is yellow but I have only used it for practice and marking underwater objects.

 

[Jcp2]

I like to launch between 40-50 feet. I have a smaller sealed one with an inflator attachment and OPV and I take a big inhale off the regulator and then orally inflate in one exhale. Then I let the spool run and put the regulator back in my mouth quickly at the same time. I’ve also attached an extra LP hose that is loose on the other end used just for dSMB inflation.
I just got a large 7’ SMB and haven’t tried it yet. This one has a baffle duck valve on the bottom so I’ll probably purge my alternate second stage. If the goal is to get it to ascend and let it lie flat on the surface so the line can be used as a reference point, then it doesn’t have to be fully inflated until you surface, and then you can use anything that works for you.

 

[kierentec]

When practicing SMB shooting I am typically in shallow water. What is the standard way to launch them? I am assuming to fill one 1/2 or 1/3 of the way you would need to be quite negative...

I've seen people use regulator exhaust out of the one they are breathing.

I've seen people purge their backup reg into it.

I've seen people use Drysuit/Inflator hoses.

What is most common? I've personally tried all 3 at least once. I didn't like how violent the powered inflation was.

Another question. How universal is the rule that a yellow SMB means distress? The SMB I have been carrying is yellow but I have only used it for practice and marking underwater objects.s

If you connect a drysuit hose or purge a reg into the open bottom, you'll create a massive buoyancy shift and struggle. But there's no need.

Start with a normal breath in your lungs and blow it into the SMB via the oral inflation tube. There's a lot of gas in your lungs on an average breath, plenty to completely fill a small smb, gets one of the big ones about 1/3 to 1/2 full. If it's blown from only 30ft, either will be pretty much full. If you were stable when you started, there's no buoyancy shift so you should stay put.

 

[jtsfour]

If you connect a drysuit hose or purge a reg into the open bottom, you'll create a massive buoyancy shift and struggle. But there's no need.

Start with a normal breath in your lungs and blow it into the SMB via the oral inflation tube. There's a lot of gas in your lungs on an average breath, plenty to completely fill a small smb, gets one of the big ones about 1/3 to 1/2 full. If it's blown from only 30ft, either will be pretty much full. If you were stable when you started, there's no buoyancy shift so you should stay put.

That makes sense... I'm surprised I didn't consider that

 

[kierentec]

That makes sense... I'm surprised I didn't consider that

Don't feel bad, it's amazing how many people don't. I taught technical diving for 6 years before someone showed me....

 

[wetb4igetinthewater]

As a rebreather diver, my only option is to use an open bottomed DSMB and be deep enough to compensate for possibly not squirting that much gas from my bailout reg.

I am open to any and all suggestions. Well, non snarky ones that is.

 

[kierentec]

As a rebreather diver, my only option is to use an open bottomed DSMB and be deep enough to compensate for possibly not squirting that much gas from my bailout reg.

I am open to any and all suggestions. Well, non snarky ones that is.

Take a breath off the loop, close mouthpiece, blow it into the bag, mouthpiece back in, take a breath off BOV, open mouthpiece (or, if no BOV, simply go back in the loop and either activate ADV or manually add dil). As long as you let the SMB go as you take that breath off the BOV/ADV/MAV, there’s still no buoyancy shift.