DSMB requirement?

[Dave Dillehay]

For the record, when doing our "Adventure Dives" way up north, or Eastside diving we provide SMBs with GPS locater beacons for all divers. We do not provide a line for sub surface deployment of the SMB. Inflating at the surface is safe and intuitive and on those sort of dives the threat of oncoming boat traffic does not exist.

Dave Dillehay
Aldora Divers

 

[KeithG]

Interesting thread. BUT: as a casual observer I think people need to make sure that they understand the difference between a DSMB and a SMB. In my reading of SB there seems to be a large amount of confusion between these 2 similarly acronymed devices.

Many years ago the Caribbean liveaboards we used mandated the use of a surface signalling device. One lob provided a "flag on a collapsible stick" while another provided a "safety sausage". We eventually bought our own safety sausage (is that a brand name?) and carry them on every dive.

Our safety sausages are a SMB. Easy to use (but highly ineffective if you let them simply lie on top of the water).

Which device is most appropriate for Coz?

 

[Dave Dillehay]

Dear giffenk,

You hit on a major problem with subsurface launched SMBs. Most of those I see in Cozumel do just lay flat on the surface, maybe flopping up now and then. The only way to make them stand erect and provide warning to oncoming boats is to get negative-- pulling down on the line, or use SMBs with weight pockets built into the base. Either way, to be successfully used, that will require the diver to carry more weight than is otherwise necessary. Sadly, the best bet for most divers who hate extra weight like me, and ascend by themselves is to carry a SMB for surface inflation. My opinion only.

Dave Dillehay
Aldora Divers

 

[SailNaked]

I think this may be answered, and I just want to say that for the price of a safety sausage, or SB why would you not carry one on every single dive everywhere? unless of course you are in a pool.

 

[amoses]

I always carry a safety sausage to inflate on the surface if necessary. It's just not deployable from depth.

 

[KeithG]

Dear giffenk,

You hit on a major problem with subsurface launched SMBs. Most of those I see in Cozumel do just lay flat on the surface, maybe flopping up now and then. The only way to make them stand erect and provide warning to oncoming boats is to get negative-- pulling down on the line, or use SMBs with weight pockets built into the base. Either way, to be successfully used, that will require the diver to carry more weight than is otherwise necessary. Sadly, the best bet for most divers who hate extra weight like me, and ascend by themselves is to carry a SMB for surface inflation. My opinion only.

Dave Dillehay
Aldora Divers

I learned this as a spectator on a LOB in Belize. One of the day boats spilled a bunch of divers across several dive sites (all within easy view of the upper deck of the LOB). All of the safety sausages were lying flat on the surface. Mostly useless?

This experience (and some reading of SB) made it very obvious that a simple short safety sausage was mostly useful on the surface, but only if you made sure its base was held below the surface in order to make it erect.

 

[Dhboner]

Great tool if you have taken the time to learn how to deploy one and practice regularly, otherwise the result can be somewhere between "America's Funniest Videos" and a serious diving incident. I have seen folks attempt to deploy an SMB at depth and end up tangled up like a tuna in a fishing net. I have seen others forget to check above and surprise the hell out of a diver above them. Learn how to deploy and inflate properly and practice regularly (we use them for ascent drills so we get lots of practice).

 

[KeithG]

Great tool if you have taken the time to learn how to deploy one and practice regularly, otherwise the result can be somewhere between "America's Funniest Videos" and a serious diving incident. I have seen folks attempt to deploy an SMB at depth and end up tangled up like a tuna in a fishing net. I have seen others forget to check above and surprise the hell out of a diver above them. Learn how to deploy and inflate properly and practice regularly (we use them for ascent drills so we get lots of practice).

SMB or a DSMB? That was the point of my original post. I own a SMB. Not a DSMB.

 

[rmssetc]

Great tool if you have taken the time to learn how to deploy one and practice regularly, otherwise the result can be somewhere between "America's Funniest Videos" and a serious diving incident. I have seen folks attempt to deploy an SMB at depth and end up tangled up like a tuna in a fishing net. I have seen others forget to check above and surprise the hell out of a diver above them. Learn how to deploy and inflate properly and practice regularly (we use them for ascent drills so we get lots of practice).

Yep.

Given the number of people --experienced divers all-- who I saw in one week who didn't know how to set their own computer when using Nitrox, actually requiring people to use a DSMB could be a real problem...and why bother carrying one without knowing how to use it safely? A surface signally buoy, sure, that's simpler and also very helpful....but given the boat traffic, I wouldn't want to ascend without a buoy overhead anyway.

 

[macado]

You're arguing semantics basically. SMB and DSMB are technically two different products but the term is often used interchangeably. A DSMB typically has an (OPV) over pressure relief valve so that if it is shot from depth the pressure can safely escape. An SMB on the other hand does not have an OVP valve or an opening at the bottom where excessive air can escape/vent; It is designed to typically only be inflated at the surface.

There is nothing stopping someone from putting an SMB on a reel and inflating it from depth, thereby making it or calling it a DSMB However in the event too much air is added at a significant depth you risk over-inflating the SMB and damaging it. I've seen plenty of SMBs inflated at depth without issues so this isn't always a concern, especially when inflating from a shallow depth.

That being said, I prefer a closed bottom DSMB or at least one with a one way value on bottom and OPV. Easier to fully inflate and they won't dump out on the surface if you're not applying downward pressure on the line. I agree with @Dave Dillehay you need to be slightly negative to get them to stand up straight however you don't necessarily need to carry massive amounts of extra weight at all. Even still, I will still argue that an SMB/DSMB laying flat is much easier to see than a diver without one.