Home > Decompression buoy

Deco buoys are inflated underwater before or during the ascent phase of the dive. A reel and line connect the buoy on the surface to the diver beneath the surface. The buoy marks the diver's position underwater so the boat safety cover can locate the diver.

There are at least 3 types of deco buoy :

• open ended (preferably with small independent weight to keep the opening submerged)
• self sealing open ended buoys (the air in the buoy expands as the buoy ascends closing a neck at the bottom of the buoy)
• closed buoys with a built in air supply and a pressure relief valve

There are several common problems with deco buoys and reels :

• The reel jambs after the buoy is inflated (dragging the diver up). To avoid this:
  • use a simpler system or a reel which cannot jamb (e.g. a weighted spool of line)
  • detach the lanyard connecting the diver to the reel before inflating the buoy (and ensure no equipment is trapped in the buoy or reel)
  • attach two reels to each other in series. If one fails the other is unlocked to reel out its line.
• part of the diver's equipment gets trapped in the deco buoy (dragging the diver up). To avoid this tie the lanyard of the reel to something solid on the sea bed before inflating the buoy (so you have time to sort the problem out)
• Whilst inflating the buoy, the diver removes the demand valve he is breathing from (and is therefore at a disadvantage in dealing with any other problems that might arise as the deco buoy goes off ). To avoid this:
  • Use a deco buoy with its own air supply
  • Use an octopus demand valve to inflate the buoy