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'How To... Plan and Marshall a RIB Dive' Page

The information expressed herein should be treated as opinion. No guarantee is given or implied that any advice on the web-site is necessarily correct. Nor might it best suit other divers and clubs due to regional and personal differences. Diving is a risk sport - all advice herein should be validated with advice from your own diving club, governing body, or approved published material before being adopted.

How To...


… Plan a RIB Dive Trip

… 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. Arrange who will tow the RIB to site and ensure access to boathouse. Make sure dive marshall can get access to box of electronics and trailer keys before the day. In electronics box must have: VHF Radio (check reception and report to coastguard on launching); GPS & antenna (log launch site co-ordinates); Echo sounder; Battery and backup battery; Equipment/transducer connector cable.

… Check the RIB safety equipment

Well before the day:

… 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.

… Prepare a break-free anchor

If critical to anchor firmly but likelihood of anchor getting stuck, make anchor break-free.

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.

… Marshal a RIB Dive

… Check RIB ready for trip

Before setting off check:

… Get RIB tubes at right pressure

RIB has multi-compartment tubes. One valve per compartment. Make sure all are inflated evenly. Inflating one compartment bends the internal walls between compartments outwards. This seems to 'inflate' next compartment but strains inner wall. Important to pump all compartments evenly so inner walls stay fairly straight. If RIB/air cold, don't inflate fully - expands as warms up, but when about to launch make sure firm as cold water will contract air an deflate slightly. After dive check not too firm and let air out to prevent warmth over-pressuring tubes again.

… Tow the RIB safely

Important points are that speed limit is 60mph motorways, 50mph other roads if no local limits apply; and can't use outside lane of motorway if other lanes in service. Good idea to have clip-on extension wing mirrors to see behind you properly. More stable when towing if nose of trailer heavy, so put heavier kit in bow of boat.

… Set the RIB up at the launch site

Remove all transport straps, prop protectors, and untie painter from trailer. Fit GPS, echo sounder, VHF radio, and battery, then test. Remove spare wheel/jack etc and leave in someone's car. Connect fuel lines to engines. Open tank vents. Lift engines prior to launch so props clear. Check drain plug in. Check kill switches fitted securely. Pump up tubes if necessary (see "… Get RIB tubes at right pressure").

… Launch the RIB safely

Check engines raised. Normally best to launch RIB light and load heavy diving gear once afloat. If steep slip/sea-bed though, may get away with kit in boat during launch.

… Radio coastguard with dive plan

Always try to notify coastguard of intentions before all dives. Example dialogue as follows.

… Avoid prop damage

Very easy to trash prop on rocks. Main avoidance is to know safe channels between slip and sea. Learn buoyage and get advice from locals. In all circumstances, keep eye on echo sounder and if gets below three metres or so take it very easy wherever you are. Learn to read sea surface.

… Use the GPS

Manual available. Read that first, but best way to learn is to use it. To get best out of it, find out Lat and Long of dive site and program this as waypoint before setting out. Get someone who understands GPS to show basics then try to use it to get to dive site.

… Use the Echo sounder

Again, manual available for basic operation but experience counts. Get used to display and what to look for on good sites. Biggest thing to understand is effect of different sea-bed depths.

… Find interesting sea-bed

Best bet is to study books/charts and get co-ords beforehand. If just looking on spec, use simple rule of thumb: unless hunting flatfish, the more varied the se-bed depth, the more interesting the dive. Rare that ridges/gullies less than a metre or so are very interesting. Remember to look at numbers more than trace on sounder - depth variations on trace look shallower the deeper the sea-bed. Drop-offs often good. If known there's a drop-off/ledge in the area, generally ridges follow coastline so best to head straight out to sea (or straight for shore if on deep side) watching sounder. Normally, steeper walls better than gently sloping drop-offs, so try to find the most sudden changes in depth. When dropping divers in, make sure they know whether on high part or low part, and which direction to head to get to wall.

… Find a wreck

Research first. Look in books and on charts to get depths & locations. Need to get to close vicinity using GPS, transits, or triangulated compass bearings.

… Deploy a shot line

Mostly to do with timing. Get someone watching sounder and someone else to release shot.

… Drop divers in the water properly

Ensure divers completely ready to dive and checks complete.

… Secure shot line to wreck

In calm conditions with experienced divers, no need to. If risk of current or divers pulling shot off wreck, best to secure it. First pair down to descend without pulling on line. At bottom, can tie off shot with waster cord (see "…Prepare a shot line"). If shot weight is an anchor/grapple, better still to loop anchor back up and secure to shot line by flukes so no risk of snagging when waster breaks. Good idea too if first pair takes small signal float down to release when shot secure so other divers know when OK to use shot line. If no waster, have to have first pair wedge shot/anchor into wreck, then last pair release it so will pull out cleanly.

… Retrieve a shot line

As long as carefully pre-planned, last dive pair to come up can use as shot line as deco buoy. Free shot end completely from wreck and ascend up line. Divers drift with shot buoy and RIB tracks as for SMB. Vital that no risk of other divers left on wreck before doing this. Only safe way is if last pair were only pair of second wave.

… Track divers underwater

On drifts, divers must use SMBs. Never try to track on bubbles. Extremely easy to lose bubbles even in calm conditions. SMBs usually no problem, but can be an issue if no current and two pairs go in opposite directions. Can easily end up widely separated. Easy to lose sight of one SMB here - especially in swells. Best avoidance is to tell divers which way to go so all go same way. If happens anyway, try to track both by shuttling between and using GPS to track positions. As soon as any hint this is getting hard, must recall at least one pair of divers. Far too dangerous to just hope to be able to find second pair after first pair surface. Don't forget too that second pair can drift a long way just while getting first pair into RIB. Don't take risks. Short dives far better than lost divers.

… Recall divers in an emergency

If several divers down and divers surface in trouble, or for any reason RIB has to leave site urgently (e.g. to answer Mayday, or sudden worsening of weather), may need to get remaining divers up in a hurry. If diving with SMBs, troll round buoys (great care needed as divers may be surfacing) and give agreed signal by tugging on lines. Club standard is four strong tugs. Can also use Thunderflash signals. If no other method available, go near to divers and rev RIB engines repeatedly - divers often take this to mean cover boat getting impatient.

… Pick up RIB divers

… Retrieve the RIB

On way back, make sure as much water out of RIB as possible. Once back at slip, best to unload heavy gear and walk it to shore before retrieving RIB. Only in calm conditions with good grippy slip and deep water at base of slip will laden retrieve work. Rarely even worth trying.

… Refill the RIB fuel tanks

Important to refill tanks fully after every expedition. Only fair way to make sure fuel costs apportioned to the right divers. Make sure oil mix is right. Fill tanks nearly full but leave a bit of a gap. Note the number of litres of fuel used. Add 10ml of oil for every litre of fuel. E.g. if 15 litres put in tank, add 150ml oil. Screw down vents securely to avoid water ingress during storage.

… Divvy up RIB dive costs

Main costs to split are:

… Garage the RIB

Once the RIB is back home, the engines need flushing with fresh water. Best way is to pump and prime both carbs and disconnect fuel lines. Attach "ear muffs" to engine water intake just above props and feed with fresh water from hose. Once water running, start engine and immediately check tell-tale has water coming out. If not, stop engine instantly and find out why. If is, leave engines running until carbs run out of fuel and engine stops. Repeat with any other engines. Hose down the RIB inside and out, and flush plenty of water round trailer - especially wheels and brake drums. Cover with tarpaulin and secure boat.


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