2014 Tank Brochure
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2014 Tank Brochure - 1

FAQ: Indoor Rowing Tanks What is a rowing tank and what is it used for? A rowing tank is simply a rowing simulator: It can simulate the rowing experience up to about 90% if designed properly. (An ergometer is ~ 60%) Rowing tanks are useful for instructing all rowers from novices working on the correct rowing motions to elite level athletes working on the most efficient stroke. Blade work improvements (i.e., handle heights at the catch, finish, crossover points), sculling synchronicity of handle position and power matching side to side can be measured and corrected. This is impossible with a mechani­ al rowing machine. c If designed correctly to replicate the forces encountered during the in-the-boat experience, the tank can be very valuable in developing the most efficient stroke at high stroke ratings. Metrics can be provided that constitute a “self coaching” system with feedback from real time curves and graphs that monitor progress that can be shown on a large screen TV as the rowing motion is taking place. Is it necessary to have “moving water” from a large pump or other source? It is absolutely not necessary to have the water moving! In the boat the water is not moving. The boat is being moved (by the rowers) relative to still water. In the boat the drive portion of the stroke is when the rower is able to accelerate the boat (increases the boat velocity relative to the water) due to the oar being locked in the water. If in a tank the gearing is the same as the boat, then the oar handle cannot be accelerated to the finish of the stroke and thus a vital part of the rowing stroke is not simulated. The result is that the rowing motion will feel very heavy during the drive at any stroke rating due to the inability to accelerate the oar handle to the finish. In the Dreher “athlete powered” tank, special gearing, blade size and different outboard to inboard ratios are used to rotate the water and are able to accelerate the handle to the finish. Stroke rates of above 30 spm per minute can be achieved. In enormously expensive “pump powered” tanks, a maximum stroke rate above 26 spm without gearing and blade size changes is as high as one might expect. If such modifications must be made to duplicate what is already achievable in a Dreher “athlete powered” tank, then why would pumps be even contemplated? Is there any benefit to a moving water tank to having the water move at racing boat velocity? The ambiance of the moving water is a plus, although you pay a huge premium in tank cost (2 to 6 times) for that ambiance. However, there are far more negatives than positives. Designing for average boat velocity is a meaningless objective. Without radical gearing changes the rowing simulation fails during the drive at all points in the handle speed curve except for right at the catch which is the slowest point in the boat velocity curve. The fastest boat velocity occurs when the oars are out of the water. It takes a very large amount of energy to move tons of water in a rowing tank at anything near average boat velocity. The velocity needed is the square of the drag and the power required is the cube of the velocity. Therefore a moving water tank is not a “green solution” (i.e., with multiple large pumps, motors, fittings and electrical controllers) and its initial capital cost and ongoing maintenance costs are much higher! Furthermore, the feeling of the stroke in a powered tank from the catch to the finish is very unlike that of a boat. As a boat accelerates through the stroke, the stroke appears to feel lighter. To stay connected and increase boat speed, the athlete has to increase handle speed toward the finish. Also, in a powered tank, the mass of the water is so large that the velocity of the water throughout the stroke is constant. Consequently, the water feels “dead” from catch to finish. As a result, the exercise for the athletes becomes, at most, an isometric. The athlete can stay connected with the water or ease off and let the water push the blade through the stroke. Can race pace ratings be achieved in a Dreher tank? Yes. Stroke ratings of 30 spm can be achieved with our athlete powered tank. Only starts and less than two minute pieces from a standing start are too short to get the mass of water moving in a human powered tank. How is Force Measurement useful in a Dreher tank? In the tank the FM system becomes a real time self-coaching tool. You have 2 curves: Force and handle speed per side per seat. In addition, there are several bar graphs: Stroke length (showing the amount of slip at both ends of the stroke), power per seat in sweep or power per side on sculling, sum of all power per side of all seats monitored and stroke rate. Data can be simultaneously displayed on a large screen TV and updated instantaneously as the stroke is created. When an issue is pointed out to an athlete, the cause is shown and corrective action can instantaneously be taken. This direct feedback from the curves and graphs generated is a very powerful tool enabling the athlete to make technique changes quickly. For ingraining the optimum, most efficient technique and crew synergism this is far more effective than a coach trying to explain with words. The tank becomes the ultimate rowing simulator with instantaneous feedback, essentially an assistant coach. Coaches can leave their athletes alone knowing that continuous improvements can be made without having to monitor the athletes continuously. Indoor Rowing Tanks Durham Boat Company, Inc. 220 Newmarket Rd. Durham, NH 03824 USA +1 603 659 7575 (Phone) +1 603 659 2548 (Fax) tanks@durhamboat.com www.durhamboat.com

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2014 Tank Brochure - 2

Dreher Indoor Rowing Tanks Product History: We designed and made our first tank in 1989. It was a 16-station sweep with 8 station sculling tank and we learned a lot from that experience. Like many people out there that design and install only one tank, by the end of the project you learn how you would do it differently the next time. The problem is that most programs can only afford one indoor rowing tank ever. After doing our own tank we had a lot of ideas as to how to make it better and by 1992 we installed our first 16-station sweep and sculling tank at Connecticut College, which is...

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