Smb

[djcheburashka]

Tobin, would you please consider making a larger smb?

The 3' one is great for GUE training but it just isn't big enough to be a reliable safety marker. On the other hand, your design for the low profile opv and inflation nozzle a real innovations. They make it possible to roll your smb up tighter and tuck it into smaller places than your competitors.

If the smb was just, say, a foot longer and 2" wider, it would be just big enough to be useable in practice, but still small enough to fit bungied in the channel of a standard ordinary backplate, and still easily inflatable orally from the 70' stop.


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I am here: http://maps.google.com/maps?ll=25.829100,-80.206028

 

[cool_hardware52]

Tobin, would you please consider making a larger smb?

The 3' one is great for GUE training but it just isn't big enough to be a reliable safety marker. On the other hand, your design for the low profile opv and inflation nozzle a real innovations. They make it possible to roll your smb up tighter and tuck it into smaller places than your competitors.

If the smb was just, say, a foot longer and 2" wider, it would be just big enough to be useable in practice, but still small enough to fit bungied in the channel of a standard ordinary backplate, and still easily inflatable orally from the 70' stop.


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I am here: Google Maps

Larger volume smb's are possible, but pretty quickly the advantages of the 1 m bag are lost. Large volume means more than a breath to fill.

There is certainly a place for larger smbs, and for serious open ocean dives I will carry a larger inflatable, but I will again note that in many cases large smbs don't always equal easier to see.

Larger SMB's are far more likely to reach the surface less than fully inflated, and usually require a large percentage of the bag be pulled below the surface to force the balance to stand up in the water. The net result can be *less* of the larger smb is standing out of the water than our 1m bag.

Tobin

 

[lowviz]

Larger volume smb's are possible, but pretty quickly the advantages of the 1 m bag are lost. Large volume means more than a breath to fill.

There is certainly a place for larger smbs, and for serious open ocean dives I will carry a larger inflatable, but I will again note that in many cases large smbs don't always equal easier to see.

Larger SMB's are far more likely to reach the surface less than fully inflated, and usually require a large percentage of the bag be pulled below the surface to force the balance to stand up in the water. The net result can be *less* of the larger smb is standing out of the water than our 1m bag.

Tobin

-put a 2' long x 4" diameter SOLAS tube on top of a standard no-dump six footer. I'd buy one.

 

[cool_hardware52]

-put a 2' long x 4" diameter SOLAS tube on top of a standard no-dump six footer. I'd buy one.

Ever tried to roll up a 2' long x 4" dia piece of SOLAS?

Tobin

 

[Akimbo]

I have not seen it in person but DAN's new SMB iteration has a ~1½” wide strip of reflective material the length of both sides the ad says is radar reflective (latest issue of Alert Diver Magazine). It will be interesting to see how effective the radar reflectivity is and how small it will roll up. It is still a 6' tube with 30-40 Lbs buoyancy so you either have to power inflate or most people will have to shoot from 100' plus for one breath to be full at the surface.

 

[lowviz]

Ever tried to roll up a 2' long x 4" dia piece of SOLAS?

Tobin

Ever see what Mid-Atlantic divers take with them into the shipping lanes?

 

[skankpile]

get a Carters 35lb smb...they make them 6' & 10' long. Awesome bag.

 

[djcheburashka]

Larger volume smb's are possible, but pretty quickly the advantages of the 1 m bag are lost. Large volume means more than a breath to fill.

...

Larger SMB's are far more likely to reach the surface less than fully inflated, and usually require a large percentage of the bag be pulled below the surface to force the balance to stand up in the water. The net result can be *less* of the larger smb is standing out of the water than our 1m bag.

Tobin

Tobin I agree with absolutely everything you said. BUT:

1) the 3' smb is so small that even fully inflated, I've found myself sometimes reaching the surface only to find that is accidentally been holding it underwater without noticing. It has less lift than a single breath.

2) whether it is big enough to be visible in still waters or not, it was rejected as "too small" by diving teams in Miami and new york. (I think the Miami guys were wrong, but it's his boat so hes allowed to make the rules.)

An SMB that was a -bit- bigger, say 4' tall (not 6), and a little wider, I don't think would be harder to inflate orally at a 70' stop than the 3' is to inflate orally at a 20' stop.

It would fill what is currently a significant gap in the smb market for a dir-focused smb that isn't bulky or a pain in the butt. And which can be stored in a non-Halcyon backplate.

(Regarding the ideal width, I suggest this: I like to store my smb in the backplate channel by running bungie loops through the cam band slots. The 3' smb is just an inch or two too skinny, rolled or folded up, to reach from one to the other so it's securely held.)


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I am here: http://maps.google.com/maps?ll=25.768894,-80.189468

 

[Akimbo]

Perhaps the intelligent way to approach the design is to calculate the average lung capacity at say 66’ (we can debate the number) and size the SMB to be full at the surface and as tall as possible.

My deep-breath-full to empty lung capacity is 4.3 Liters (no idea if this is average or not). Taking 4 liters that provides:

Depth = Displacement
5’ = 10.43 Lbs.
10’ = 11.80 Lbs.
15’ = 13.17 Lbs.
20’ = 14.54 Lbs.
25’ = 15.91 Lbs.
30’ = 17.28 Lbs.
33’ = 18.11 Lbs.
35’ = 18.65 Lbs.
40’ = 20.03 Lbs.
45’ = 21.40 Lbs.
50’ = 22.77 Lbs.
55’ = 24.14 Lbs.
60’ = 25.51 Lbs.
65’ = 26.88 Lbs.
66’ = 27.16 Lbs.
70’ = 28.25 Lbs.
75’ = 29.62 Lbs.
80’ = 31.00 Lbs.
85’ = 32.37 Lbs.
90’ = 33.74 Lbs.
95’ = 35.11 Lbs.
99’ = 36.21 Lbs.

I personally like to have 25-30 Lbs of buoyancy but that is also arguable. I can often put 1½ breaths into the bag before letting it go, but one breath is ideal.