What's the lock(knob?) on SMB for?

[nohappy]

Some of the smb oral inflator have a knob(?) or a lock on it. You can rotate that so that you won't be able to blow any more air into it. What's the purpose of that? To prevent air leaking? But it still has over-pressure valve, it still leaks somehow. What's the point of that?

 

[Jcp2]

That’s the valve that they source that’s normally part of snorkel vests. A custom valve would be more expensive.

 

[nohappy]

@Jcp2 Thanks for your reply. In other words, do you mean that is not originally designed for SMB? And does it have any purpose on snorkel vest?

 

[Jcp2]

I think the factories that make smbs make a lot more snorkel vests or other inflatable life preservers, as it’s all the same concept, just a different shape. It’s reassuring to a new snorkeler that feels the need to use a buoyancy aid that the aid will remain inflated.

 

[M-Cameron]

@Jcp2 Thanks for your reply. In other words, do you mean that is not originally designed for SMB? And does it have any purpose on snorkel vest?

prevent the inflator from accidentally being depressed, allowing air to unintentionally escape?

 

[Steve_C]

I think it is a pull. You pull and you can inflate. The over pressure valve is not a leak. If you shoot an SMB from depth it will greatly expand as it arises. The overp ressure value is to keep it from expanding too much. Shoot a bag from 90 ft and you will see what happens.

Personally if I am going to shoot a bag I like to do it as soon as I can. That is from depth. Gives boat on the surface an earlier indication of where I am and where I am going.