Rapid Ascent Due to Broken Delayed Surface Marker Buoy (DSMB)


During a relatively shallow dive to 13 meters (43 feet), I experienced an incident with a DSMB (Delayed Surface Marker Buoy).

The dive was carried out on a relatively calm, sunny day in a channel with visibility at about 2.5 meters (8 feet). After about 15 minutes of underwater filming, we proceeded to ascend, a normally straightforward process: deploy the DSMBs and gently surface.

But diving can spring unexpected challenges. The DSMB I was using is the self-inflating type using a small previously charged cylinder. Owing to the local conditions, it was necessary to hold the reel, inflate and release the buoy while being slightly negatively buoyant on the seabed.

On this instance, the ratchet release lever broke at its weakest point where it pivots, leaving the reel jammed at precisely the moment when the buoy should be released. The simple solution would have been to let go of the reel and recover it later. However, when the lever broke, its spring caught my glove like a fish hook and resulted with me attached to the inflated DSMB rapidly going up.

It was relatively shallow depth and a full DSMB can lift very quickly. You can be topside in a matter of seconds. I had to make a rapid decision.

Removing the glove and letting the glove and reel go was not an easy option, as it would take too long (gloves don't come off easily). Letting go of the reel and tear the glove free of the spring seemed the only thing to do.

In the few seconds that it took to recognize the problem and execute a solution, I had ascended at a rapid rate; my computer log registered an ascent rate peaking at 72 m/min (236 f/min) for 7 meters (23 feet). By the time I disconnected from the DSMB, I was close to the safety stop depth (6 meters/20 feet). I was able to dump air from the suit and BCD to further slow my ascent, and the last 4 meters (13 feet) was taken very slowly.

Once on the surface, it was clear that no one was aware that there had been a problem. Despite feeling fine once on deck, I explained what had happened. I was then asked if I felt anything unusual that could indicate a bend, was told to relax, drink plenty of water and lie down. Oxygen was offered and kept handy but I thought was not necessary with such a shallow depth and short bottom time.

This might not seem to be a particularly spectacular incident, but then many incidents start as something small then escalate. Yes, shallow and short duration, but what if the incident had occurred at 30 meters (98 feet) after a bottom time of 40 minutes? What if the spring could not be so relatively easily pulled free of the glove?

edited by Jeanette Moore