DSMB Technique

[Angelo Farina]

My instructor told me. The reason being I dive in cold water and a frozen reg is to be avoided.

Avoiding freezing is a good reason for not using the octo.
But in cold water you should NOT use an octo, you should use two fully independent regs on two separate valves, which mitigate strongly the issue.

 

[BlueTrin]

One thing I was wondering with the crack bottles using a small bottle with a manual valve instead of one off gas charges.

Aren’t they at risk of severe water ingress?

 

[Edward3c]

One thing I was wondering with the crack bottles using a small bottle with a manual valve instead of one off gas charges.

Aren’t they at risk of severe water ingress?

Your thinking of the AP 0.1Lt bottles. Yes, if you open and let go water will get in. There also to small to be tested. I swopped mine out for a hose attachment years ago.

 

[Kendall Raine]

Here, dives for which freezing is an issue are made with valves allowing to put two regulators and cutting them independently even when using a single tank. Is this not a common practice elsewhere?

H (and to a lesser extent Y valves) valves are used in the the US, but why not avoid the issue of second stage free flow altogether by not using the second stage in cold water conditions.

 

[Wibble]

One thing I was wondering with the crack bottles using a small bottle with a manual valve instead of one off gas charges.

Aren’t they at risk of severe water ingress?

AP do a fixed price service and test for the crack bottles (AKA mini cylinders). If the cylinder fails, they’ll replace it for a supplemental fee. Or they’ll replace the cylinder and service the valve for a fixed fee.

AP Diving | Servicing Guidelines & Prices

Get full details of AP Diving’s Servicing Guidelines and Prices for Rebreathers and BCDs.

www.apdiving.com

 

[rjack321]

This just means you are underweighted. You need to have sufficient weight on so you do not ascend if inflating your dsmb.

Yeah no. Bigger SMBs have wayyyy more lift than any weight belt could ever hope to hold

 

[Ayisha]

Removed

 

[blueskies_up_ahead]

Avoiding freezing is a good reason for not using the octo.
But in cold water you should NOT use an octo, you should use two fully independent regs on two separate valves, which mitigate strongly the issue.

I do have a cold water setup with two separate first stages. Still would not use that to inflate the DSMB. Even when I dive with just one, I will not use the secondary reg. Again, it's around my neck. And I don't want to use a method that makes no sense for most of my diving. Why would I?

 

[steinbil]

I do have a cold water setup with two separate first stages. Still would not use that to inflate the DSMB. Even when I dive with just one, I will not use the secondary reg. Again, it's around my neck. And I don't want to use a method that makes no sense for most of my diving. Why would I?

You should be comfortable switching regs, so switching to your backup so you can use the longhose to fill an open-ended bag should not be an issue. And you must have an open-ended bag if you're filling it with exhaust bubbles. I prefer closed bags (SMBs and lift bags), and if the bag is too big to inflate orally, I'd use my dry suit hose. But if you insist on using open-ended bags, I would take the advice you've been given to use the longhose instead of keeping the bag by your face. Entanglement is the major concern with your method, and that is alleviated by holding the bag further away from you and using the long hose to purge into the bag.

 

[Angelo Farina]

You should be comfortable switching regs, so switching to your backup so you can use the longhose to fill an open-ended bag should not be an issue. And you must have an open-ended bag if you're filling it with exhaust bubbles. I prefer closed bags (SMBs and lift bags), and if the bag is too big to inflate orally, I'd use my dry suit hose. But if you insist on using open-ended bags, I would take the advice you've been given to use the longhose instead of keeping the bag by your face. Entanglement is the major concern with your method, and that is alleviated by holding the bag further away from you and using the long hose to purge into the bag.

I agree entirely. And if you press GENTLY the purge button, the resulting airflow will be the same or even lower than when you are breathing, so the risk of freezing is minimised. No one forces you to press fully the purge button for filling the buoy in 0.1s...