Many sailors have already dived under their boat to clean the underwater hull or to cut a caught line from the propeller. This is often done with a queasy feeling and under time pressure due to a lack of air. Cold water, discomfort, a racing heart. It's nice to be back on board!
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The underwater world is fascinating and full of secrets. Countless ships and treasures lie on the seabed, surrounded by corals and sea creatures of all sizes, shapes and colours. For humans, the wet depths may seem as threatening as the endless universe, but once you have experienced the pleasure of floating, you will never forget the experience.
With the right technique and equipment, the boat can be the ideal starting point for a skilful dive. Once the sometimes bulky and heavy equipment is on board, it can be easily moved to any anchorage. A dive is a refreshing change of perspective, especially in calm and scorching heat.
Scuba diving (Scuba)
With this type of diving, a compressed air diving device is used to keep you supplied with breathing air. This artificial air supply enables dives that can last several hours. Compressed air is usually used in the steel cylinder attached to the back, but other mixtures such as nitrox are also used.
With an air-filled buoyancy compensator, the diver can regulate his buoyancy by inflating or deflating and position himself in the three-dimensional space of the water. Scuba diving is practised as a hobby or professionally in different areas. When diving from a yacht, there are a few important things to bear in mind, provided you have a licence such as the Open Water Diver from the PADI instructors' association. Firstly, the heavy cylinders must be stowed safely. They should therefore be stored horizontally and secured with straps so that they do not roll on the swaying boat to prevent injuries and breakage. The back box and a customised wooden rack are ideal for this purpose, similar to the storage of wine bottles. The valve on the bottle can also be protected with a protective bracket or a home-made cap.
Safety and organisation when diving from a yacht
Getting into the water is not a big problem. From the dinghy with the reel backwards or from the yacht with a big step away from the boat. Don't forget to deploy the swim ladder! It is more difficult to get back on board with the heavy equipment and fins. Take off your fins in the water, hang them around your wrist and then up the ladder. You may also need to take off your buoyancy compensator jacket and tank and hand them up. As a general rule, divers should never go to depth alone and always remain in visual contact with each other.
Yacht photographer and professional diver Klaus Andrews: "You don't need scuba equipment to inspect the ship. The risk of marring the gelcoat with the tank is not small. Diving in the Baltic Sea is also rather pointless for hobby divers, as the water is cold and visibility is often poor. There are not many fish to be seen either. In the Mediterranean or in tropical waters, it's a different story: the water is warmer and clearer, and there is much more life to observe."
A complete set of diving equipment including neoprene, a dive computer or even a compressor can quickly add up to several thousand euros. Alternatively, most of the equipment can also be hired from diving centres, which can be found all over the world.
In terms of price and logistics, scuba diving is the most challenging way to go diving. It is only worthwhile in a top area - but offers by far the longest diving pleasure.
Free diving (apnoea)
Freediving is about staying underwater for as long as possible with just one breath. The roots of freediving are deeply rooted in human history, as it was the only way to get hold of coveted shells, sponges or pearls for a very long time.
Today, the most widespread form is spearfishing, whereby apnoea is often associated with crazy record attempts by extreme athletes. However, mastering this original diving technique also offers several advantages for sailors. You can dive anywhere at any time, for example to clear the anchor or free the drive from annoying bycatch. No expensive equipment is required, just a mask, snorkel, fins and, if necessary, weights and a dive computer.
Even in emergency situations under water, this acquired skill ensures calm behaviour instead of panic, promotes well-considered decisions and thus increases the chances of survival. Best of all, as no compressed air is inhaled, there is no need to worry about decompression.
Advantages and techniques of freediving
But which people are actually suitable for this? Instructor Alexis Girard explains: "Everyone, without exception, has the natural ability to hold their breath for much longer than they would expect. The only reason why this is difficult is the increasing stress level under water, which triggers the breathing reflex and causes the diver to resurface as quickly as possible. The first technique taught is therefore to relax. Everything revolves around this, because you can't dive under stress."
In the second step, the urge to breathe is controlled. Sudden diaphragmatic contractions signal a lack of oxygen and feel like blows to the pit of the stomach. These spasms increase the blood flow to the heart and are even helpful in the event of a lack of oxygen. Nevertheless, blackouts can occur, which is why you should never dive alone.
"Scuba diving is a sport that involves looking outwards to discover the underwater flora and fauna. When freediving, divers look more into their inner self in order to immerse themselves completely in the moment - similar to meditation," says Girard, describing the main difference between the two types of diving.
The learning progress in apnoea training is considered to be very fast, as most people are able to hold their breath significantly longer after the three-day basic course.
Deep snorkelling device
Rainer Michelbach from Swabia is the pioneer of this diving system specially designed for boaters. The prototype of the Freediver deep snorkelling device was presented to Germanischer Lloyd in 1997 and has been continuously developed ever since. The principle: a compressor on the surface draws in ambient air through a valve, compresses it and pumps it through a hose to the diver's mouthpiece. This continues for as long as the compressor battery lasts. Depending on the diving depth and battery capacity, this is between 30 and 70 minutes.
The compressor can either be connected to an on-board battery or follow the diver on an inflatable lifebuoy in its own battery mode. Crews are able to help themselves in peace and quiet. For small repair jobs, for example. Due to its compact pack size, the system is very popular with long-distance sailors and has been sold between 2,500 and 3,000 times in total. Depending on the pressure setting, a diving depth of up to 14 metres is possible. As it is compressed air, as with the Scuba, care should be taken to ascend slowly at depths of six metres or more. The rule of thumb is: do not ascend faster than your own air bubbles. Or no more than ten metres per minute.
Mini bottles for diving
For short dives at shallow depths, there have been several mini tank models on the market for some years now. The Mini Dive Air, for example, is a 0.5-litre aluminium cylinder with 200 bar and a regulator including mouthpiece directly on the cylinder. According to the manufacturer, this model enables five to ten minutes of diving time. The cylinder can be refilled manually with a 15-minute hand pump work-out. However, great care must be taken with these systems, as there is a high risk of overestimating one's technique and ability. If the inexperienced diver gets into the slightest critical situation, far more air will be consumed under stress, which would immediately empty the tank. The same applies at slightly greater depths.
Decompression sickness (DCS)
Diver's disease is caused by insufficient decompression following increased ambient pressure. When diving, the body absorbs nitrogen, which is released again during ascent. If decompression is too rapid, bubbles form in the tissue, which can damage the brain, lungs and other parts of the body.
There are two types of DCS: a mild, usually easily treatable form and a severe one that causes long-term complications. Type 1 shows symptoms such as itchy skin and tingling, while type 2 can cause paralysis, unconsciousness and impairment of higher brain functions. If DCS symptoms occur, whether mild or severe, the diver must leave the water immediately and receive pure oxygen. Severe symptoms require an oxygen chamber.
Safety stops slow down the ascent in order to reduce nitrogen saturation. The depth and duration of the stops depend on the diving depth, the bottom time (time from descent to the start of the ascent) and the residual saturation from previous dives. The figures are calculated using a decompression table or a dive computer. If you do not dive deeper than ten metres, you are not at risk of DCS, although PADI generally recommends making a safety stop at a depth of three metres when surfacing.
Fear of sharks
What remains is the primal fear of encountering a larger shark. Even though divers are extremely rarely attacked, diving expert Alexis Girard has valuable tips on how to behave in the event of an encounter: Keep an all-round view, as the predators like to attack from behind.
If a shark becomes too curious, the Frenchman recommends direct eye contact and a vertical orientation in the water. Keep calm, even if it is naturally difficult. In most cases, however, this is enough to signal to the animal that you do not fit the prey pattern. Discard any fish caught with the harpoon. Otherwise, surface slowly and keep the shark at a distance with your fins. Don't forget to take a selfie!
