Riding a DSMB up from a deep wreck???

[johndiver999]

So nobody can explain what the logic is for the activity shown in the video?

 

[dberry]

I though several of us have explained: It was a class exercise on using a DSMB for alternate buoyancy in the event of a wing failure.

Others have suggested it's not a strategy they would use, but that's not really relevant to your question of what was being practiced in the video.

 

[johndiver999]

Thanks, but why not hold it
For the whole ascent? If the intent is to provide lift?

 

[northernone]

Thanks, but why not hold it
For the whole ascent? If the intent is to provide lift?

Here's my guessed as a diver who has rode a dsmb for lift:

1. Ascending directly to the surface without deco stops on a deco dive is less desirable.
2. A dsmb can serve as a dsmb if the diver isn't directly attached to it. Easier to send up the one being used for buoyancy and hold the string than to try to launch a second dsmb while riding the first and hold a deco stop.

I haven't been trained by Chatterton. Maybe some of his colleagues/friends/students can speak to specifically what he is demonstrating.

Cameron

 

[dave22387]

You can have a different school of thought. That’s fine.

What’s not fine is saying things that are incorrect. Saying you can’t dive deep wrecks with a balanced rig is, simply, incorrect.

If you read back I didn't say you can't. I said there are times when it isn't feasible. Example, if I dive dry here is S. Florida I need no insulation. Most of the deeper wrecks here can be done with double AL 80s and a stage granted you can actually stage them somewhere. If you're doing a hot drop on the stern and doing a drift deco from the bow you can't stage your cylinders somewhere so a stage isn't really doable. Therefore bigger doubles are required. With pumped double108s, an 80 with 50%, and a 40 with O2 and my trilam even at 500psi/15 feet I'm still negative. The only way you can dive balanced on a wreck is with stages unless you have the ability to use ditchable weight which in my case I can't. How do you propose diving a wreck without stages in a balanced configuration?

 

[dave22387]

I'll talk to Chatterton later today and report back. From speaking to some of his former students I don't believe it's an emergency procedure but I will confirm with him.

 

[Ryan Mcshane]

If you read back I didn't say you can't. I said there are times when it isn't feasible. Example, if I dive dry here is S. Florida I need no insulation. Most of the deeper wrecks here can be done with double AL 80s and a stage granted you can actually stage them somewhere. If you're doing a hot drop on the stern and doing a drift deco from the bow you can't stage your cylinders somewhere so a stage isn't really doable. Therefore bigger doubles are required. With pumped double108s, an 80 with 50%, and a 40 with O2 and my trilam even at 500psi/15 feet I'm still negative. The only way you can dive balanced on a wreck is with stages unless you have the ability to use ditchable weight which in my case I can't. How do you propose diving a wreck without stages in a balanced configuration?

Negative with or without stages?

 

[PfcAJ]

If you read back I didn't say you can't. I said there are times when it isn't feasible. Example, if I dive dry here is S. Florida I need no insulation. Most of the deeper wrecks here can be done with double AL 80s and a stage granted you can actually stage them somewhere. If you're doing a hot drop on the stern and doing a drift deco from the bow you can't stage your cylinders somewhere so a stage isn't really doable. Therefore bigger doubles are required. With pumped double108s, an 80 with 50%, and a 40 with O2 and my trilam even at 500psi/15 feet I'm still negative. The only way you can dive balanced on a wreck is with stages unless you have the ability to use ditchable weight which in my case I can't. How do you propose diving a wreck without stages in a balanced configuration?

Keep the stages on you?

 

[dave22387]

Keep the stages on you?

That would certainly be an option if you're not going inside. Outside touch dive for sure. Penetration I don't think I'd want three slung tanks.

Negative with or without stages?

That's without the stage just backgas, 50 and O2. With mix the a stage is negligible anyways.

 

[Ryan Mcshane]

That would certainly be an option if you're not going inside. Outside touch dive for sure. Penetration I don't think I'd want three slung tanks.



That's without the stage just backgas, 50 and O2. With mix the a stage is negligible anyways.

Weight check should be with back gas only. Deco bottles aren’t part of your weight system in a balanced rig.