SMB for light diver

[Seefa]

I have the 6 foot surface marker pro DSMB Surface Marker which is very well built and offers 20 kgs of lift.

I am a relatively light diver, I dive a soft plate, aluminum tank (s80) and a 3mm wet suit with 3kgs of lead.

No matter how hard I try I cannot keep the DSMB upright on the surface, I found that I need 2-3 extra kilos and to deflate my wing fully to be able to hold it upright.

I used other smaller DSMBs and they seem to be a lot easier to keep standing while doing my safety stop.

I'm now looking for a smaller DSMB to purchase. I want one that is ideally just as tall as my current one but with less lift.

Ideally something in the $20-50 price range.

 

[Dan]

Does the 6’ SMB have open bottom? It won’t have enough air pressure (rigidity) to keep it up even by submerging the bottom to about a foot below the surface. I got rid of those & use the close bottom one with valve that you can blow it with your mouth or low pressure hose (see the SMB picture, below). I even add a low pressure hose with blowgun for it so I don’t have to take the 2nd stage out of my mouth to blow the SMB. I just stick the blowgun tip to the SMB nozzle & puff some air into the SMB (see the red hose on my reg, below)

Although the smaller open bottom SMB has more rigidity to stay up at atmospheric pressure, it is too small to see by the boat at a distance, especially with 3’ wave. I won’t use DSMB smaller than 6’ for good visibility & with at least 100’ string on spool.

Also I prefer to launch it from underwater so I won’t need to use too much air as the air would expand as the DSMB ascending. It would be a lot of blowing at the surface, otherwise. At 100’ (~ 4 atmosphere), you just do one puff of air through the nozzle, let it ascend and expand 4 times of the initial air volume. Then you top it off at the surface for rigidity.

At the surface, I would pull & hold the string down about 6” below the surface to keep the DSMB straight up.

 

[Seefa]

Does the 6’ SMB have open bottom? It won’t have enough air pressure (rigidity) to keep it up even by submerging the bottom to about a foot below the surface. I got rid of those & use the close bottom one with valve that you can blow it with your mouth or low pressure hose (see the SMB picture, below). I even add a low pressure hose with blowgun for it so I don’t have to take the 2nd stage out of my mouth to blow the SMB. I just stick the blowgun tip to the SMB nozzle & puff some air into the SMB (see the red hose on my reg, below)

Although the smaller open bottom SMB has more rigidity to stay up at atmospheric pressure, it is too small to see by the boat at a distance, especially with 3’ wave. I won’t use DSMB smaller than 6’ for good visibility & with at least 100’ string on spool.

Also I prefer to launch it from underwater so I won’t need to use too much air as the air would expand as the DSMB ascending. It would be a lot of blowing at the surface, otherwise. At 100’ (~ 4 atmosphere), you just do one puff of air through the nozzle, let it ascend and expand 4 times of the initial air volume. Then you top it off at the surface for rigidity.

At the surface, I would pull & hold the string down about 6” below the surface to keep the DSMB straight up.

View attachment 449169
View attachment 449170

It has a baffle so it keeps the air in, my issue is with how much force I have to pull to keep it upright so I'm looking for a slimmer one for this reason.

Unfortunately I don't have the luxury of filling it at depth as most of my dives end at around 5 meters (15 feet) so I need to be able to fully inflate it from that depth. I'm not too concerned with not being found as the waters here are calm and the the boat usually follows the divers. The DSMB mostly serves three purposes, a place for the divers with me to gather to for their safety stop, the notify nearby boats in the area of our exact location and to inform the dive boat that were about to surface.

 

[Dan]

The purposes of using DSMB is pretty much universal, I think. I use it for the same purposes as yours:
1. To tell the boaters above to not run over us as we ascend.
2. To tell our boat where we are.
3. Most importantly to tell our boat early enough where we are before getting blown away by swift current during safety stop too far for our boat to notice.

As far the shallow diving limitation, well, you have 150 psig (~ 11 atmospheres or 100m depth) from the low pressure hose to pressurize the SMB. That’s more than plenty.

I got this DiveSmart DSMB with 100’ spool from Amazon for $60. I’m not sure if you can get it at the same price in Oman, but it’s made in China. So, I would think it would be available all of over the world. It has small enough diameter to stay rigid & straight up 5-6’ over the surface with air pressure coming out of my mouth.

It also has light reflector to reflect any flashlight during the night. It can stay up rigid enough for me to strap on an eye-piercing strobe (see the strobe picture, below) at the tip of the SMB.