Lifting Bags, Shot Lines and Decompression Stations Andy Thomson

DUSAC -Advanced Diving Techniques Introduction Lifting Bags Shot Lines Types, Construction, Deployment and Retrieval Decompression Stations Types October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Lifting Bags Types Open Ended Closed with valve Self-inflating When to Use Retrieving items such as shot lines When Not to Use Taking items from wrecks that you shouldn’t be! October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Shot Lines Why use a shot line Marked entry/exit point - aids safe dive marshalling and boat cover Shortest route to/from surface More comfortable/secure Datum point for searches Why not use boat’s anchor? Line moves with boat movement Cover boat should be mobile at all times DON’T DO IT October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Types of Shot Lines - 1 Simple Shot Advantages - it’s simple! Disadvantages Not easily made vertical Does not adjust for tidal rise/fall Bottom-Tensioned Shot Advantages – always vertical More complicated! Risk of line tangling Bottom Tensioned Shot Line not often used Buoy Line Shot weight October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Types of Shot Lines - 2 Top-tensioned Shot Advantages Adjusts for tidal rise/fall, provides near vertical line Can give precise position of dive site Disadvantages More complex, counterweight tangle Main part of line will move Not ideal in current or wind Counterweight October 25th, 2003 DUSAC -Advanced Diving Techniques

Shot Line Construction Thick enough to grip for recovery, usually about 12mm Length At least as long as it is deep Plus a couple of metres Surplus line Needs to be kept tidy, better at the surface Bouy Enough bouyancy to support weight (50% more) Weight – Heavy enough! Counterweight Approx. 5 – 10kg Depends on conditions Tide Bouy? Small bouy to show current direction October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Shot Line Connections Bouy, Line & Weights Karabiners Knots Attachments Karabiners Short loops of cord or other ropes secured by Prusik knots Rolling Hitch Shortening the line Karabiners Chain senneting, sheepshank October 25th, 2003 DUSAC -Advanced Diving Techniques

Shot Line Deployment Once deployed, re-check! Prepare before arrival at dive site! Deploy on boat cox’n order only! Think about direction of current! Once deployed, re-check! October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Shot Line Recovery Controlled Recovery Lift bag bouyancy same or slightly less than weight of shot Divers fill bag so it is neutrally bouyant or slightly negatively bouyant. Lift to surface from boat, slowly pulling on line (can become uncontrolled) Bouyant Recovery Lift bag bouyancy greater than weight of shot Divers fill bag to send it to the surface Boat AND divers stay well clear October 25th, 2003 DUSAC -Advanced Diving Techniques

Decompression Stations A decompression station is simply a shot line that divers are carrying out stops on! Methods of making this easier and safer are varied. All require divers to return to the shotline for use. Dives should be Planned Accordingly! October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Deco Stations – Types 1 Can be as simple as a loop tied into a shot line Back-up deco cylinder – perhaps with Nitrox? Lazy Deco Stations Extra line, weight and bouy attached to main shot line Back-up deco cylinder may be attached Can be detached to drift with current - Requires Diver ‘logging’ system October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Deco Stations – Types 2 Decompression Trapeze Requires two additional bouys, weights, lines and solid bars Bars can be set-up at various or multiple depths. Back-up deco cylinder may be attached if needed Again, it can be detached to drift with current - Requires Diver ‘logging’ system October 25th, 2003 DUSAC -Advanced Diving Techniques

DUSAC -Advanced Diving Techniques Deco Stations – Types 3 Deco' Stops 48m 6 / 9m - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 24m Recommended Stop 30Kgs 5 Kgs Peg Board CFT Extended Range Course October 25th, 2003 DUSAC -Advanced Diving Techniques