Surface Marker Buoy (SMB) : Ideal length

[idive2]

Every diver should have a smb as a minimum but I'm seeing many more reel/smb combinations than I have in the past.
Will probably start using the 4.5 ft marker in seas over 2-3 ft.

 

[boulderjohn]

Several posters have hinted but perhaps not said clearly that the choice of the size of the SMB depends a lot upon the environment in which you will be diving. If I think there is a possibility that I will be lost in high seas with people looking for me, I want one big enough to be picked up on Google Earth. I can sit on the surface and fill that sucker up at my leisure. Another use is to provide a good ascent line without concerns about being found in heavy seas, diverting boat traffic, etc. In that case a smaller bag has the advantages of being easier to carry during the dive and being easier to deploy when needed.

 

[Tortuga68]

Exhalation is one method but not using just 1 breath. You deploy by opening it to the 2nd stage vent but I usually do 3-4 big, sharp breaths. The more preferred way is to use another regulator like a safe second or a stage cylinder

All of those methods will result in positive buoyancy, which needs to be controlled. I disagree that using an alternate is the 'preferred' way to inflate, I prefer oral for small (one breath) SMBs, or exhaust for larger. Apart from the freeflow risk mentioned earlier, the average diver doesn't carry a stage/pony.

 

[The Chairman]

All of those methods will result in positive buoyancy, which needs to be controlled.

That's really why I prefer to use the LP hose to inflate. It's way quick to fill and you can fill/release the bag way before the extra buoyancy starts to affect the diver. It's important to keep your digits and body clear from the bag as it flies to the surface, but make sure your buddy is ready with a zip knife in case you get entangled.

 

[danvolker]

Several posters have hinted but perhaps not said clearly that the choice of the size of the SMB depends a lot upon the environment in which you will be diving. If I think there is a possibility that I will be lost in high seas with people looking for me, I want one big enough to be picked up on Google Earth. I can sit on the surface and fill that sucker up at my leisure. Another use is to provide a good ascent line without concerns about being found in heavy seas, diverting boat traffic, etc. In that case a smaller bag has the advantages of being easier to carry during the dive and being easier to deploy when needed.

I have one of these still...from when I used to do tech dives off of Fort Pierce, 25 miles out I would fit in the mc storage pouch between my back and the backplate.....it worked perfectly, but was a pain to fit back in to the pouch, so you would not want to be yanking it out like a normal smb on every dive ...

Life Support Rafts | Halcyon

 

[phoenix31tt]

another method a diver recently told me about is using the exhuast while holding down the purge button for the following reasons:

1. bungied octo doesnt lend well to using your secondary to fill
2. regulator never leaves your mouth
3. its enough air being pumped in there in a short space of time to allow for proper filling without having to deal with the extra bouyancy

anybody seen/heard of this method?

 

[Tortuga68]

That's really why I prefer to use the LP hose to inflate

Do you mean the inflator hose?

another method a diver recently told me about is using the exhuast while holding down the purge button for the following reasons:

1. bungied octo doesnt lend well to using your secondary to fill
2. regulator never leaves your mouth
3. its enough air being pumped in there in a short space of time to allow for proper filling without having to deal with the extra bouyancy

anybody seen/heard of this method?

No. I gather the idea is a quicker fill as opposed to using your exhaled gas (which may require multiple exhalations depending on SMB volume)?

 

[phoenix31tt]

Yea quicker fill to avoid having to deal with buoyancy issues of multiple exhalations, by the time you "feel" the buoyancy effect you will already have enough air for a proper deployment


At least that's his thinking

 

[Tortuga68]

I guess in non-cold water it makes sense, for a duck-bill SMB, although I like the idea of using 'redundant' gas to fill the SMB (not for any real reason, just appeals to me)

What I really don't like about that idea is that you need one hand to operate your purge, instead of having both hands free to manage the SMB/spool/reel

Either way, if you're deploying from depth it's a non-issue since you don't need to fill the SMB anyway. Personally if deploying from shallower depths and using a larger SMB, I just get negative and use finning (up/down) to control my own buoyancy

 

[The Chairman]

Do you mean the inflator hose?

Yes. It's called by a number of names. It's the only hose that is easily removable to do this.