Delayed SMB's


Don't go ballistic with your blob

THE practice of deploying a delayed Surface Marker Buoy (SMB) towards the end of a dive has done much for diving safety. However, as many divers have discovered, there are potential problems associated with this technique.
I regularly read reports of divers being dragged into an uncontrolled buoyant ascent as a result of using a delayed SMB. Such ascents carry the risk of lung damage and missed decompression, and can be lethal.
The classic scenario goes like this: the diver starts to fill the delayed SMB, the SMB is released, the reel jams, and the diver is pulled upwards, unable to release the reel. He or she cannot dump air fast enough to control the expanding buoyancy of his or her suit and/or BC, so hits the surface after an extremely rapid ascent. In some cases the buddy is also dragged along for the ride.
A few pieces of advice are worth bearing in mind: