Plan a RIB dive
All comments in “Plan a general dive trip” apply. Special thoughts on RIB. Plan the diving for RIB abilities. Long sea trips a bad idea if: more than four or so divers; lumpy, windy or cold weather; separate waves of divers being taken; extreme diving being done; lone boat with single engine. Think about air. If compressor convenient during surface interval, get divers to take one cylinder (plus money for fills!). If not, take two and allow for effect on speed of extra weight. Carefully plan timings for state of tide at retrieval slip – make sure enough water at slip for safe easy retrieve when RIB will be back. Check in books <<REFERENCES>> of slips/launches. Arrange who will tow the RIB to site and ensure access to boathouse. Make sure dive marshall can get access to box of RIB kit and boathouse/rib/wheel clamp keys before the day.
Check the RIB safety equipment
Well before the day: Check Oxygen pressure in Oxygen kit and top up if necessary; Check first aid kit contents all present and in good condition; Check flares still in date; Charge handheld VHF Radio battery. For engines, need: spare prop, split pins and spanner; spare spark plugs and plug spanner. Ideally should also have: Paddles; RIB tube puncture repair kit; Spare SMB reel and buoy; A couple of spare ropes for boat towing etc.
Prepare a shot line
Best to get this done before the day. Assess likely depth of wreck from books/charts. Allow for tide state. HW springs can add several metres, LW springs much shallower. Decide if can shot top of wreck and thus what depth from shot to surface. Measure out line to this depth plus only 10% or so (more than this will cause shot line to be angled and give long swim down). Fix main buoy here. Pay out two or three more metres and fix smaller telltale buoy. Fix shot or grapple to deep end with slightly weaker line so that if shot jams, only lose shot not whole line too. Loosely lay shot line into large bucket in boat from buoyed end first, shot end last. If deco dives being planned, fix carribiner or similar to line at stop depths for stage cylinders. If desired, also tie thin strong waster cord to bottom of shot line. This allows first divers to tie off shot line to wreck with waster to avoid shot being pulled off, but waster will break with strong pull to allow shot to be retrieved from boat.
Prepare a break-free anchor
If critical to anchor firmly but likelihood of anchor getting stuck, make anchor break-free. Shackle anchor chain to nose of anchor. Run chain loosely along shaft. Fix nearest links to anchor eye with strong cable ties or thin strong cord. Anchor warp tied off to free end of remaining chain as normal. While anchor in use, cable ties pull anchor into sea-bed as normal and anchor bites. In emergency, use very strong pulling or RIB engines to strain against anchor warp until cable ties snap. Chain then only fixed to nose of anchor. More pulling will then easily pull anchor flukes free and lift anchor nose-first.