The most original form of swimming is movement in standing, open water. How similar swimming in a counter-current pool is to swimming in open water depends on the quality of the counter-current system.
Water is the most important source of life and health for humans, and movement in water — swimming — has always been an important cultural skill. Water is needed to (survive), sometimes swimming too. But swimming means much more to most people: it's meditative, sporty and challenging at the same time. Swimming is a great workout for young and old. Swimming keeps you young and can reduce stress.
In addition, you experience a kind of weightlessness in the water. The water carries your body, it seems to take over your weight. In a large pool or lake, this experience is not disturbed by currents. The feeling of flow only occurs while swimming through the movement of your arms and legs. We decide how fast the felt flow goes or how much effort we want to make. We are completely in control.
It doesn't matter if you swim for fun, for fitness or for Olympic gold — the starting point is exactly the same for all swimmers, but they do deal with it very differently. Some simply enjoy the pleasant feeling, the light massage, the gliding through the water. Sports swimmers improve their condition and technique in an environment that optimally relieves their joints. Competitive swimmers and pros analyse their technique to ultimately be just that hundredth of a second ahead of the competition. Most people don't have the opportunity to swim in open water in their environment. Swimmers want to stay focused and reach their goal (daily) without feeling the hustle and bustle of a public swimming pool. A counter-current pool is the only swimming environment that can simulate open water. That is why more and more people are looking for their own indoor or outdoor swimming pool with a countercurrent.
But unfortunately, people who swim in their new private pool for the first time are often extremely disappointed with their expensive purchase. They believe that the flow is too weak, insufficiently controllable or too turbulent. The current can even push your body sideways, which can really hurt. How is that possible, it all sounded perfect, right?!
Technically, a counter-current pool should simulate stagnant water, because the natural swimming environment is stagnant water. In principle, it is possible to already allowing the water in a swimming pool — across its entire width, length and depth — to flow fairly consistently and without turbulence in one direction. With an unlimited budget, this would be achievable. But the average swimming enthusiast doesn't have an unlimited budget. The good news: When you swim, you always move within a relatively small swimming zone — more or less the length and width of your body plus the room for movement of the arms and legs — and if the current inside the swimming zone is ideal, you can swim just like in open water. Your own swimming area is always smaller than the total swimming area of your pool.
The minimum dimensions The swimming zone that a swimmer needs to swim really well are therefore determined by the swimmer's body height and width. The swimming level determines the minimum flow rate. You should therefore create a swimming zone that is between 60 cm and 80 cm wide and at least the total body length + outstretched arms and that has a flow rate of at least 0.4 m/sec. (health swimmer) up to at least 2.0 m/sec. (top level). At the end of this document, you'll find a table where we've calculated what you need to equal swimming in stagnant water.
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As part of my own research and through my practical experience in the world of counter-current swimming pools, however, I have come across something remarkable: Advanced swimmers in particular often experience current slightly differently than what you measure purely physically. Time and again, I heard from swimmers that they experienced certain speeds as just not enough, even though the correct values were on the speedometer.
So to satisfy the swimmers — my customers — I had to go the extra mile. After extensive discussions and calculations, I was able to map out the relationship between “objective” and “felt” speed — just a little bit harder. A flow velocity V = 1.2 m/s (or around 1:23 min./100 m) appeared to match a felt speed of 2 min./100 m.
So that's why my Swimm Intelligent Pools are all designed in such a way that the physical speed is just a little bit more powerful than it would be necessary based on the continuity equation. The Intelligent Pools therefore offer even advanced, demanding swimmers sufficient challenge and a true-to-life experience.
With the continuity equation Q = A x V, you can calculate how much water you have to move how fast to create a certain speed in your swimming zone.
An example:
A swimmer wants a swimming area that is 60 cm wide and 40 cm deep. He wants to swim V=1.2 m/sec., which corresponds to a felt speed of 2 min./100 meters. He will do this in a current that touches the entire length of his body and outstretched arms.
Water volume calculation: Q=A x V
A = 0.60 x 0.4 = 0.24 m2
Q = 0.24m2 x 1.2m/sec = 0.288m3/sec.
In other words: 17.28 m3/min = 1036.8 m3/h.
In order to swim nicely at the desired speed, the swimmer therefore needs a flow machine that is at least 1,036 m3 water can move per hour.
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Width of the flow
Various technologies attempt to simulate open water swimming on a limited water surface: systems without currents (e.g. swimming elastic), jet streams, and counter-current pools with propeller or turbine propulsion.1
In a jet stream, water is pushed into the pool at a very high speed by one or more jets (sprinklers). Just like a jet of water, a jet creates a hard, point-shaped flow. There isn't really a swimming zone — the current doesn't touch the swimmer's legs and the current is too narrow — even completely point-shaped with one jet. The swimmer usually has to pay attention to his position in relation to the jet stream to avoid being pushed sideways.
In counter-current pools with a propeller or turbine drive, the water flows into the pool through a grille. Turbines (a type of small propellers) are less powerful than swim propellers and can therefore move less water. This affects the dimensions of the grille and thus the quality of the swimming area. With both technologies, you can create a swimming zone that is deeper, wider and longer than that of a jet stream.
Backflow
Turbulences, sideways and contrarian currents prevent you from swimming properly. You can't focus on your technique or just swim in a relaxed way.
With jet streams, the suction of the water is in the upper part of the pool wall, i.e. next to the jet (s). As a result, the water flow from the device is diverted sideways or downwards fairly quickly. The swimmer is therefore not fully carried by the current, so it takes a lot of energy and effort to stay above water. This comes at the expense of speed and if the swimmer continues to correct his swimming movements, he will most likely slow down even in open water.
In some systems with a propeller or turbine drive (at the front), the water is also extracted here, but in the lower part. The current is diverted down at the back of the pool and flows back forward across the bottom. In these pools, you have a complete swimming area with one-way current;
With the most advanced technology, the water is extracted at the back and transported back to the front outside the inside of the pool. The water in the pool flows in one direction; contrary flow is excluded. Due to the technical complexity and the associated costs, this technique is only used in absolute premium models.
Impact on swimming movements
The flow of one or more jet streams is point-shaped, rather turbulent and insufficient to carry the entire body. The swimmer must continuously monitor his position in the current and must also adjust his movements to stay afloat. The resulting swimming movements can slow the swimmer down..
With jet streams, the suction of the water is in the upper part of the pool wall, i.e. next to the jet (s). As a result, the water flow from the device is diverted sideways or downwards fairly quickly. The swimmer is therefore not fully carried by the current, so it takes a lot of energy and effort to stay above water. This comes at the expense of speed and if the swimmer continues to correct his swimming movements, he will most likely slow down even in open water.
In countercurrent pools with water extraction at the other end of the pool, the flow determines the position of the body in the water. Like in open water, the swimmer can focus all movements on moving forward and thus on swimming (more) quickly. If the movement pattern practiced here is automated, a swimmer will swim faster even in stagnant water. The relaxing, therapeutic effect of the swimming movements is maintained.
Conclusion
If you want to swim in a relaxed way or if you want to train and improve your technique, you need a spacious swimming area with a wide, even flow. The wider, more uniform and softer the suction current across the pool, the closer it is to swimming with countercurrent to swimming in open water. In this case, you don't have to adapt your swimming technique to the current. You will probably even improve your swimming technique and, in addition, you will even feel like you are “gliding” through the water. The higher the flowing water volume and the higher the flow rate, the sportier you can swim. However, if the current looks like a point beam, you will be forced to adjust or change your swimming movements so that you can no longer move naturally. In this case, unfortunately, you no longer make the swimming movements you would make if you were swimming in open water. And the harder this water jet is, the harder it becomes to swim against it. In addition, the flow of this point beam will push you aside.
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The three basic technologies for countercurrent systems are often described differently in practice. Swimm uses the following definitions:
Countercurrent system
(also: counter-current swimming system)
(compact) pool with countercurrent, the flow is created by means of a pump, turbine or propeller.
Jetstream
counterflow technology based on one or more sprinklers (jets) and a pump. Flow is quite turbulent, hard, punctual. Very high inflow rate, low water volume.
Turbine-powered swim system
counter-current technology based on a turbine (ø approximately 12 cm). Swim turbines move a lot of water, but always operate at high revs. The flow is wider and less turbulent than a jet stream but still fairly uncontrolled.
Propeller-driven swim system
countercurrent technology based on a propeller. Swim propellers move a lot of water at low revs. The flow is soft, powerful, broad, laminar, free of turbulence and fully adjustable. All Swimm counter-current pools work with a propeller system.
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We have now reviewed the various countercurrent technologies and identified the importance of a spacious swimming area. It is important to know what countercurrent velocity you need. This analysis starts at your own speed. The standard way to indicate a swimmer's speed is minutes per 100 m.
If you don't know your speed in the water, here's how to find out:
t your own speed. The standard way to indicate a swimmer's speed is minutes per 100 m.
1. Go to a public swimming pool and swim 100 m at your fastest speed.
2. Use a stopwatch to measure how fast you are over 100 m.
3. Think about whether you would improve your performance if you were to swim very often. “Slow” swimmers are likely to swim twice as fast, very sporty swimmers start at a high level and are unlikely to swim 100% faster.
4. Now you know your (target) speed.
5. If you are going to use your future pool with several people, the fastest swimmer determines the speed.
Based on your own speed, you can now set the required flow rate. On the next page, you'll see a table with different profiles of swimmers. Find the swimming style, level, and technique (s) that best describe your situation.
In the “Speed/Swimmer” column, you'll see a speed that swimmers with this profile usually reach. For swimmers who are (also) active at competition level, we show a desired speed instead.
If your measured speed differs significantly from the average value in the table, look at the closest combination of profile and speed. In the last column, you can now see the minimum flow rate (in m3/hour) you need.
Now you can decide which pools/systems are right for you. According to the product information, if more than one outflow point is used — e.g. a combination of multiple jets — you must divide the value m3/hour by the number of outflow points. Please note that the width of the current is at least the same as the width of your swimming zone and that the current also reaches the entire length of your body.
* target speed/training goal
What do you pay attention to when looking for your ideal pool?
t your own speed. The standard way to indicate a swimmer's speed is minutes per 100 m.
1. Spacious swimming area
2. Soft, wide, uniform flow over the entire swimming zone (length, width and depth)
3.Sufficient capacity to ensure the desired flow rate/speed (value in m3/u or l/min., see previous chapter)
4. The lowest possible inflow rate. This prevents turbulences
5. Water extraction at the other end of the pool to force flow
6. Fully adjustable flow rate, optionally with display (m/sec.)
7. Avoid air bubbles in the water. This has a negative impact on your position - you swim “deeper” in the water, which negatively affects the technique - and worsens your vision in the water.
Using this document, you can calculate the minimum flow rate needed to meet your swimming needs. You now also know the advantages and disadvantages of all countercurrent technologies and you now know what to consider when purchasing a counter-current pool.
Swimm's Intelligent Pools are among the most advanced counter-current pools and offer an unparalleled swimming experience. Every swimmer can therefore make use of the Swimm appropriate to their sporting background, available time and wishes and expectations. Whether you're a health swimmer or a top athlete, everyone benefits. For example, you can first work (hard) with the help of the training schedule you have determined and then go for a few more laps. Or you can do another interval training before relaxing at your pool. Almost anything is possible!
The Swimm team wishes you the best of luck in finding your perfect pool and, of course, lots of swimming fun!
