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Ocean sailor Feature

Diving from a Yacht

By Dick Beaumont

A perfect day for me is fishing while I’m sailing to a dive spot. To accommodate this, my passage plan and destinations have been determined by a desire to dive somewhere no one else has dived, or an iconic dive site that otherwise one would have to book specialist liveaboard dive holidays to get to.

I began diving back in the late ‘60s, inspired by the first sport diving couple, Hans and Lotte Hass. I was so passionately determined to learn to dive that I attended Thurrock BSAC dive club on my 16th birthday, the first day I was old enough to learn to dive. Some 51 years later, after more than 9,000 dives and having spent a year of my life underwater, my passion for diving hasn’t been sated and I’m still excited by the prospect of tomorrow’s dive, especially if I’m diving from somewhere off the beaten track from White Dragon, my Kraken 66.

I first began diving from sailing boats on Moonshadow, my previous yacht, and initially started by diving from the 3.4mt RIB she held in her davits. That worked, but it was a lot of aggravation. The RIB  had to be launched, then all the dive kit had to be loaded into this small inflatable, someone then had to do a boat watch on both the RIB and the yacht. That method severely limited the diving I could do, so I worked out a method of diving straight off the yacht. 

 Anchoring the yacht to dive isn’t preferable, since the best dive sites are going to be in close proximity of coral/rock reefs or wrecks and dropping a 50kg anchor and 10mm anchor chain onto a reef or wreck isn’t acceptable or desirable, since it will destroy the reef and also be impossible to recover back on board after the dive.

To be able to dive from a yacht it will need four design attributes:

A dive ladder or at least a deep swim ladder. A herringbone configuration is best but it needs to run down at least one metre (3’3”) into the water and be strong enough to carry a diver and their dive gear.

A reverse sheer transom, so they can climb back up the transom without assistance.

An area to kit up, such as an aft cabin coachroof.

Side gates in the life line/stanchion rails.

Equipment

  1. It’s a good idea to use weight shot pouches rather than solid cast lead dive weights.
  2. You will need a big soft rubber mat to cover the kit up area especially hatches and get coated areas that don’t fare well with contact from dive tanks and weight belts.
  3. In addition to the standard dive kit each diver must carry a delayed SMB (surface marker buoy) and reel.
  4. The yacht will need a forward sonar and high definition down view sonar/fishfinder.
  5. Ideally the yacht will have a dive compressor, this should be housed in the stern lazarette as you don’t want to be moving the dive tanks around the yacht deck too much.
  6. Each diver must wear a compass, so they know the direction they are going.

Locating the dive site

The perfect dive site is a pinnacle that is submerged to 4-5m depth so the yacht can pass over the dive site without fear of grounding. An atoll that sits just below the draft depth of the yacht is also good but otherwise coral walls are good too.

I very rarely look at dive guide books as normally there isn’t any for where I’m diving and there are special considerations for dive sites that you can dive from a yacht. You will need to get much closer to reefs and cliff faces than you would normally consider.

A common practice is to stand out too far, into deep water, but this will give the divers a tiring long surface swim to get to a depth they are ok to descend to, and if there is a current running, they may not even get to the sanctuary of the seabed before they are swept away.

Don’t plan a dive to start within 2 hours of sunset. You’ll need good light to locate the divers at the end of their dive.

Step one

Find an area on the chart plotter where the contours are close together. Headlands are often excellent dive sites, but the confluence of currents that form around them might cause problems in forecasting where the divers are going to be at the end of their dive.

Step Two

Using the forward sonar and with the plotter track on and set to the minimum distance, not time intervals. Head in slowly, stand well off, say 50m, stop the vessel and engage neutral, and watch how fast the yacht is drifting with the current. Maximum viable will be about 1-1.5kts.

Note the speed of drift and the direction. Change the track of the drift to a different colour and save it (See Fig 2).

Step Three

Continue heading in slowly at a 90-degree angle to the wall or pinnacle with one eye on the forward sonar and one hand on the gear lever, ready to go hard astern if there’s a surprise. Come in until the wall or pinnacle is clearly showing ahead and the seabed is around 20m on the down view sonar. Mark this spot with a waypoint. Now go astern 10m or so and stop and go into neural and again drift to create a track of the drift and note the speed of the drift.

Step four

Now work out how far a diver will drift in an hour, assuming they drift at the speed and direction of the current you experienced on the last drift test, and mark that position with another waypoint, that will be the planned dive exit point.

Go back out in a circle but this time head in towards the wall at an acute angle going uptide against the current you have noted. Head along the wall parallel to where you think it is at the same distance off the wall from your marked waypoint and scan ahead and below (See Fig 3). 

On the run parallel to the wall, select the dive drop point and mark it with another waypoint.

Dive plan

The brief to the divers must be that they enter the water and drift with the current keeping the wall on one side only. If it’s a pinnacle or small island, do the same so the helmsman knows which way the divers are going around it. Maximum dive time must be 1 hour and they must be told not to fin with the current thereby outstripping the speed of the current, if the current is weak the diver should maintain steady progress. They must continue in the planned direction of the drift dive, however; 

a. If they must change direction they must send up the delayed SMB within a few minutes.
b. They must send up the delayed SMB 30 mins into their dive in any case.
c. The helmsman must make it very clear that it is the divers’ responsibility to swim out into deep water to meet the yacht, the yacht must not go in to pick them up.
d. The divers must stay together after their assent during the surface swim out to the yacht.
e. When the yacht is heading to them and they are far enough from shallow water and the reef they should sit in the water 2m apart.

Drop off

Once the dive plan is agreed divers must fully kit up. During kitting up time it’s worth slowly tracking along the wall or dive site, looking for the best spot to drop the diver following a track created as in Fig 3. When the divers are fully kitted and ready waiting at the gate that faces the wall the helmsman again follows the track as in Fig 3 and at a speed of max 2 knots. The helmsman should give a count down as the entry point is arrived and put the engine into neutral and then shout GO’ at the dive entry point. The two diver do a giant stride entry 3 or 4 seconds apart. Due to the weigh on the vessel the first diver will be clear of the entry point before the other jumps in. The helmsman turns immediately out to sea, and engages forward gear once well clear of the divers.

Watch / Boat cover

During the time the divers are down the yacht should stand out to sea 200-400m or so from where the divers will be drifting with the current. If the wind on the yacht accelerates, reduces or alters the drift direction and speed of the drift, the helmsman should correct that and come back to a position offshore where he thinks the divers will be (see Fig 5), assuming they will progress at around ½ knot.

The helmsman should be bearing in mind that he has marked where the divers might get to in an hour at maximum drift speed, the divers will be putting up a delayed SMB at 30mins or sooner, so the helmsman will always know the furthest the divers could possibly be, even if they haven’t sent up a delayed SMB as planned.


The yacht should be standing offshore of the expected exit point as the divers will drift towards the yacht rather than the divers drifting away from the yacht.

Pick up

When the helmsman sees the divers back on the surface he must make an approach plan that allows him to pick them up with the vessel facing away from the reef or at least only parallel to it.

The helmsman must steer the yacht between the divers, head to wind and waves and can only be making slow headway, 1-knot max at the point it arrives with its bow between the divers.

f. The helmsman must go hard astern once he loses sight of the divers at the bow, to take all weigh off the vessel, then puts the engine into neutral.

g. As soon as the vessel is alongside each diver, the diver swims to the hull and shouts ‘ON’ loudly, the helmsman will not be able to see the divers but now knows where they are.


h. The divers swim to the transom and reboard via the dive ladder.

Note: if the vessel is still making weigh the divers must let go of the stern so the helmsman can carefully go astern to take off the weigh, without fear of reversing over the divers.

Remember you are very unlikely to be within realistic reach of a decompression chamber so be conservative with your air reserve and bottom time.

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