Blue water diving is the closest you may get to a space walk without being an astronaut. It is diving in a clear water environment in which there are no fixed objects and no functional bottom. It may also be the most frightening, disorienting, hazardous dive you will ever make.
Blue water diving is not deep diving. It can be done in the top 60 feet of a water column, which may be a little or a long way from the bottom. The sense of suspension in a liquid environment can be very disorienting or threatening. You may feel exposed or unprotected. You may get confused about which way is up or down. You may feel as if you are falling, even while maintaining a constant depth.
Considering scaring your booties off with a blue water dive? Then do it the smart way, as a planned and properly executed dive. This type of extreme diving needs some additional equipment and a game plan each member of the team embraces.
Pre-Blue Water Training: In the swimming pool, perfect your buoyancy control skills. Be able to hover; achieve neutral buoyancy, then control your depth by breath control. Practice clipping and unclipping tether lines with your eyes open and closed. Practice communicating with hand signals and line jerks. Simulate emergency procedures and responses such as a diver off the tether or the approach of a shark. When these skills seem natural in the pool, move to inshore waters of 30 to 60 feet and test your skill proficiency while also dealing with currents, waves, surge and the use of lines in open water.
Canceling A Blue Water Dive: It is not advisable to blue water dive in winds greater than 20 knots, when the boat will be blown around too much. Heavy swells can create hazardous conditions by jerking the downline. Strong currents that make it uncomfortable or impossible to stay near the downline are reason to terminate a dive. Turbid, low visibility waters are another. While you may go blue water diving to see large marine life, the presence of aggressive predators, such as the great white or other dangerous sharks, Orcas, Leopard or Elephant Seals, may present more personal danger than you are willing to accept.
Equipment and Dive Tips: The kingpin of planning is diver safety. It may be hard for you to imagine you would have trouble knowing up from down, or that your head could get weird images of sharks about to chomp; but it is very real. Veterans with hundreds of dives in all types of conditions are surprised at how they react on a blue water dive.
The buddy system is modified to have up to three tethered divers monitored by one safety diver. The safety divers responsibility is to watch the tethered divers, communicate via line signals, maintain safe and correct depths, and respond in the event of danger or accident.
Divers tethers are typically 30 foot long, one-quarter inch diameter lines attached by a quick-release shackle to the divers BC or, preferably, to a separate harness. The other end of the tether line is attached to a trapeze bar. The trapeze can be anything that accepts multiple attachments and allows the safety diver to quickly and easily reposition the lines. As the divers move around, the safety diver unclips and rearranges the lines to avoid tangling. The safety diver is generally attached by a three to five foot tether to the downline.
Following are some tips on making your downline and trapeze bar apparatus and how to rig the lines.
1. Downline can be a continuous 150 foot length of three-quarter inch double braided Dacron line.
2. Loops three inches in diameter are tied every five feet. This allows for 100 feet of depth and 50 feet for knots, loops and surface line.
3. Loops every 10 feet are marked by a plastic piece that has the depth written in large bold letters and is attached via nylon cable ties.
4. The bottom of the line (100 feet) is shackled to a three to five pound weight mounted on a five gallon bucket lid. This is the bottom flopper stopper.
5. A loop of surgical tubing or bungee cord material can be clipped between two loops near the surface as the wave dampener.
6. A trapeze could be a 3/8 by 3 by 24 inch piece of polypropylene with holes drilled in the sides for the harness and tether lines. If you plan to have three divers, make at least six holes so there are open spaces to untangle lines. Add stainless hardware of shackles and a swivel clip.
7. Diver tethers are 30 foot lengths of braided Dacron line. One end passes through a polypropylene washer and is secured to a four ounce fishing weight. The other end goes through a swivel clip eye and ends at a two inch stainless ring. The weighted end of the line will gently sink so it is less likely to get entangled. The big washer stops the fishing weight from passing through the swivel clip.
8. The diver safety harness could be a shoulder or waist model. The waist model is easily made of one inch tubular nylon webbing with a Fastex plastic squeeze clip. An attachment lanyard slides on the waist belt. No equipment should be hung from the tether attachment lanyard so you may want to add a second lanyard. The color coded, one-half inch tubular nylon lanyards are about one foot long. Each has a stainless steel spinnaker shackle, to which a short release lanyard is secured. Separate lanyards are used for tether line and equipment to ensure that the weight of the divers equipment cannot be inadvertently transferred to the downline when the diver is released from the tether.
Safe depths are adhered to by use of a marked downline and appropriate instrumentation on the divers. Some blue water divers wear redundant depth gauges, watch and computers. An instrument that records the deepest depth attained should be used.
Downlines may be securely attached to a large or small boat and float, depending upon the surface conditions. Depths should be marked at regular intervals, such as every five or ten feet, by knots or numbered depth markers. The free end of the line should be weighted with less than a ten pound weight. In deciding whether to attach the downline to a boat or float, consider which method would make the line the least susceptible to up and down movement from swells and horizontal movement from surface current movement. If you attach the downline to a large vessel with substantial windage area, the moving vessel may carry the downline through the water faster than is comfortable for the divers. An elastic wave damper line section near the surface and a flopper stopper at the bottom help reduce the line pulls from surface wave action.
The safety diver communicates with the divers via line pulls. One tug might mean Are you ok?, two tugs, I want your attention, and three tugs, Return to the downline. If necessary, the boat monitor can terminate the dive by slowly pulling the whole downline assembly into the boat. Some blue water divers believe the person left in the boat should be capable of single handedly pulling a scuba diver into a small boat.
A typical dive plan calls for the first diver to use one-third of his/her air, then return to the marked line and begin a slow ascent while holding the line. After a safety stop at ten to 20 feet, the diver surfaces, still in contact with the line. Once on the surface, gear can be clipped to short lines hanging over the side of the boat or handed to the boat crew. The diver should climb into the boat so the safety diver is relieved of the need to track the divers movement and the boat crew can focus on assisting the next surfacing diver.
Blue water diving is not for everyone. And, those who have done it for fun or scientific research confess it is some of the spookiest diving they have experienced. If you want to push your mental limits and ignite your imagination, then plunge into a world with no boundaries. Learn what it feels like to be a worm on the hook at 60 feet as pelagics race past!