Divernet




 

I CAN RECOLLECT MANY MORE MISHAPS INVOLVING BOATS THAN I CAN UNDERWATER INCIDENTS. Nothing too serious, but all things that shouldnt have happened.
     Perhaps this reflects the amount of time allocated to improving boat-handling and seamanship compared to the diving training that most divers undergo. But divers are responsible only for themselves and their buddy, whereas the driver of a club dive-boat is typically responsible for half a dozen divers at a time.

Follow that SMB
You dont get much practice in following a surface marker buoy on a boat-handling course, but its a handy skill. I like to stay close to the SMB that is furthest downcurrent and look back at those further upcurrent. Sometimes, when the sun is low in the sky, I modify this to keep the sun behind me.
     Arising from this task, here is a classic example of doing all the right things at the wrong time. We were diving in an area of stable slack water that was shrinking as the tide turned. One pair of divers strayed a bit too far out of the slack area and started moving with the current.
     Both were experienced divers and their briefing had covered this eventuality, with instructions for them to surface. Unable to tell whether they were surfacing or not, the boat-handler decided to pull them up by the SMB line.
     Thats not a problem if done gently at a controlled rate, but the boat-handler was a little over-enthusiastic. The divers were already in midwater and on their way up. The first few hefty tugs on the line separated the pair, so there was already one diver who was unmarked.
     The next few tugs were so strong that the diver holding the SMB became concerned about the risk of a rapid ascent and let it go.
     The boat-handler kept on pulling, and ended up with a tangled mess of line and reel in the bottom of the boat, and two missing divers.
     Standard procedure here is to mark your position before beginning a search pattern. The boat-handler threw out a shotline and buoy, which was promptly pulled under in the current.
     This was a doubly pointless exercise, as the location was only 10m from a charted rock which already marked the position quite adequately.
     As for the missing divers, they were located easily enough by the flag one was carrying and the delayed SMB the other had inflated.
     While all this was happening, I was having a nice dive in the slackwater area, my SMB being diligently followed by our second boat.
     What had happened here was perceptual narrowing. The boat-handler had got in a fluster and over-reacted, when all that had been necessary was to follow the SMB.
     Although large overfalls could form, it was only just after slack water and they were not so large as to be dangerous to the boat or divers.
     As I have noted before now, there are very few tricky situations under water in which there is no time to Stop, Think and then Act. As a reader rightly added in a subsequent letter, having acted, you should Review the result (creating a neat STAR sequence).
     If it is necessary to recall divers by pulling up an SMB line, make sure you do it gently so as not to cause a fast ascent problem. Once you know the divers are ascending, let them complete their ascent at their own speed. Whatever you do, dont pull them through a decompression stop.
     I would guess that more than 50 per cent of the attempts to recall divers by pulling on an SMB line that I have witnessed have resulted in either uncontrolled ascents or divers letting go of the line to avoid one.
     As for the lost shotline, the boat was sent back next day to wait for slack water and, predictably enough, the shot buoy popped to the surface as the tide turned, and the line was recovered.
     When it comes to recalling divers, other techniques are available. Something that every dive boat should carry is a thunderflash - a small pyrotechnic gizmo that makes a loud bang.
     It is important to make sure that a thunderflash is under water when it explodes, otherwise all the noise will be on the surface and the divers will hear nothing. It is also important that it should not go off right next to the tubes of an inflatable or RIB. You can guess the consequences of that one.
     Two ways of achieving this are to tie the thunderflash to a paddle and hold it under water and clear of the boat, or to tie it to a fishing weight and throw it clear.
     A thunderflash is a single-use device. I have heard of repeatable-use units that employ compressed air to similar effect, but have never seen them or witnessed them in action.

Second-guessing delayed SMBs
     If divers are planning to ascend on delayed SMBs, I aim to maintain a position where I can spot the markers as they break the surface.
     This means being aware of where the divers are most likely to come up, positioning the boat to view the area and staying alert.
     Having said that, I witnessed one situation in which the divers lost the wreck, swam in the wrong direction, and were more than half a mile away from where they should have been before sending up a delayed SMB.
     Fortunately they were spotted because their cover boat had, in some ways negligently, left the area of the wreck to play around while the divers were down, and just happened to be in the vicinity of their DSMB!

The string broke
     One of the weaknesses of small outboard motors is the pull-cord starter mechanism. This has a tendency to wear through and snap at the most inconvenient times, especially if it has just received a good workout because of a temperamental motor.
     As with all problems, prevention is better than cure, so a pre-departure check should include gently pulling the cord out all the way and inspecting it to see if it is perilously worn, especially at the far end.
     Divers tend to get sloppy about things like that, so a starter cord breaking at sea is not an uncommon occurrence. Outboard motor manufacturers have anticipated such problems by building notches into the flywheel so that an emergency starter cord can be wrapped around it. Often this necessitates unbolting the starter mechanism to provide access to the flywheel.
     With the right-size spanners in the toolkit, I used to think the only real hazard in all this was of catching small nuts before they dropped into the sea.
     Then I witnessed someone with the wrong nut half undone - the big nut in the middle that holds the recoil spring in. A few more turns and bits of starter mechanism would have been catapulted across the sea in all directions.

Jump leads
     Electric-start outboards are not immune to starting problems, and perhaps it was an over-pessimistic view of the reliability of an outboard that resulted in the next problem that arose.
     Some friends had borrowed their club RIB and invited me along for the day. The outboard had a bit of a reputation as a bad starter, so it was no great surprise when it failed to open up first time. After half an hour of changing sparkplugs and winding away, the battery was almost flat, so we ran some jump leads from a car at the waters edge and carried on trying to raise some life.
     After another hour we had given up, and pulled the boat out of the water. We were packing away the tools when a piece of paper with instructions was found in one of the boat boxes - reminding us of the direction in which the kill switch should be set.
     Outboard fixed, we re-launched and went diving. But the story doesnt end there. At the dive site the engine stalled, and when we tried to re-start, the starter motor whirred without engaging.
     All the earlier winding had shaken part of the motors mechanism loose. On the way to the dive site it had dropped into the sea, never to be seen again.
     Unlike smaller outboards with pull cords, this motor was too large to have an emergency starter on the flywheel. We scrounged a tow home from a passing hardboat.

To PAN or not to PAN
     During another broken starter incident, two boats were operating with most of the divers under water when the starter broke on one of the outboards.
     The boat-handler had just returned from a marine VHF radio course and was able to put new-found knowledge into immediate practice. The boat was disabled, so a PAN-PAN call was made to the Coastguard.
     For readers who have not completed a VHF course, the phrase PAN is used to convey a sense of urgency, but where the boat is not in imminent danger of sinking, in which case the term MAYDAY would be used. An example given in the VHF manual is a yacht with engine failure.
     A consequence of making a PAN call is that the Coastguard treats the matter seriously and takes immediate action. The nearest lifeboat was launched.
     In the meantime, the second boat recovered the divers, and another boat took the one with the broken starter under tow.
     The incident was over before the lifeboat was out of harbour.
     Before writing about this, I contacted Maritime Coastguard Agency headquarters in Southampton to see what it advised. It turns out that even with very serious situations, things usually start with a normal call to the Coastguard, and it is the Coastguard which makes the decision to escalate things to urgency or distress status.
     PAN or MAYDAY are rarely used to initiate a rescue. So perhaps it would have been wiser simply to call the Coastguard without any distress protocol and discuss the situation.
     An amusing outcome was the way in which the press treated the incident.
     The local daily newspaper reported that the lifeboat was launched to go to the aid of a dive boat, unfortunately missing out the resolution of the incident and implying that the divers had been saved by the lifeboat.
     The national press then picked up on the story and reported it with some relish. We were soon to learn how: Divers from a sinking RIB had been rescued by the lifeboat...

The trouble with compasses
Instruments are always a problem on small boats. Even modern waterproof radios, echo-sounders and GPS sets have a habit of misbehaving when exposed to salt water.
     It might be safe to use GPS to find a dive site, but never depend on it to find your way home again. Simply take reciprocal compass bearings on your way out, so that you can follow them back later.
     Returning from an offshore dive, I encountered an interesting problem with this approach. The shoreline was obscured by a light haze and we were following a compass bearing home.
     Being in an inflatable with tiller steering, there was no fixed compass. One of the divers was holding a hand compass and pointing the direction to steer for the boat-handler. It soon became obvious that no matter where the boat was pointed, the compass bearing was constant. We didnt have a clue which direction the boat was actually following.
     It took a while to find out why the compass was not behaving. To line it up with the boat, the diver holding it was leaning forward on one of the tubes and holding it next to my steel diving cylinders. Sitting up and moving away from the cylinders soon sorted the problem out, and we were back on course.

The missing weightbelt
Getting the weight distribution right makes a big difference to the performance of a boat, especially on long journeys. It is usually much more comfortable to sit towards the back of the boat, so to counter this we had loaded all the heavy kit as far forward as possible, with our weightbelts tied in right at the bows.
     The sea was lumpy and we bounced around a bit on the way to the dive site. On arriving, one of the weightbelts was missing. We were sure it had been loaded. Could it have bounced out Or were our memories playing tricks - had the belt been left on the slip
     We were diving in two shifts anyway, so I lent my belt to the diver whose weights were missing. We had a couple of nice dives each, then returned to shore.
     Later that night, we were washing the boat out and noticed a lump near the stern. The missing weightbelt had slipped under the floorboards and was now right at the back of the boat, between the boards and the inflatable keel.

Makeshift anchor
Back at the beach between dives, in a calm sea, a couple of weightbelts tied to the painter (bowline) makes a convenient temporary mooring.
     In shallow water it actually holds better than the light anchors typically carried by a RIB or inflatable.
     You have to be good with knots, and it doesnt work well with shotbelts. You also have to remember to recover the belts before driving off.
     On more than one occasion I have seen boat-handlers question the poor performance of a boat after leaving the beach, only to discover a pair of weightbelts still dangling from the bow.

Free beer
Above the dive site, the job of a boat-handler is often to act as dive marshal for the divers in the boat, getting them into their kit and into the water in the right order. And it is here that my number one tip can be applied.
     One of the most common points at which kit gets dropped is when the divers are rolling into the water. As the boat-handler, you are often in the best position to observe this kit falling loose, so be prepared to reach out and catch dropped kit before it sinks out of sight (so long as this manoeuvre doesnt compromise your main role, of course).
     The more heroic the rescue of a valued item of diving equipment, the more grateful the diver will doubtless be and the more beer he or she will buy you later.


The
The early stages of hands-on training involve familiarisation with the controls...
...carrying
...carrying out controlled turns
...at
...at slow speeds...
...and
...and the principle of getting up on the plane...
Gently
Gently coming up to a mark...
...in
...in a club environment boat-handlers can practice their approach work for picking up divers, using wind and current...
...coming
...coming alongside smoothly...
...executing
...executing advanced turns at speed


  ZEN AND THE
  ART OF BOAT-HANDLING

  1. Catch dropped gear and get free beer
  2. There are throttle settings other than full speed. Drive at a speed that suits the prevailing conditions. The objective is to arrive at the dive site with divers in a fit state to dive
  3. Currents, wind and waves all influence the movement of the boat. Use these to your advantage
  4. Load divers and equipment to balance the boat. Adjust this balance to suit the conditions
  5. The best journey is not necessarily a straight line. Steer round tidal races. Use the coastline to hide from heavy seas
  6. For two-stroke motors, check that the fuel is oiled
  7. Check that the radio works
  8. Before launching a boat, make sure you will be able to recover it
  9. Grease trailer wheel-bearings before launching the boat. Hot wheel bearings are most vulnerable to salt water getting inside
  10. After launching, dont park the trailer with the brake on. The brake shoes could seize
  11. Watch out for shallow rocks. Use the divers to keep a look-out
  12. Plan offshore trips to go out facing the prevailing weather and return with it behind you. If it blows up, at least you can get home.
  13. Take note of the compass bearing needed to get home
  14. When recovering divers, remember to maintain a lookout for your other divers
  15. Keep count of the number of divers on board. Be especially careful when two or more boats are working together and recovering each others divers
  16. When approaching a beach with surf, remember that you cant tell how big it is from the sea
  17. If an outboard wont start, before getting the tool kit out check the kill switch and make sure the fuel line is connected
  18. Dont assume that other boats, jetskis or windsurfers know the rules of the sea or will follow them
  19. If there are other boats at the dive site, approach slowly and be aware that there may be divers in the water
  20. Seek advice from the Coastguard before a problem develops into an emergency.



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