FAQ: Indoor Rowing TanksWhat 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 cal rowing machine.

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

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 still in operation today and that facility is just as nice as it was when it was installed. See below the Connecticut College Tank in 2012:

Connecticut College in 1992 (below):

The tank is a rowing simulator with a modular design to provide indoor training and technique work throughout the winter to compliment other winter indoor or outdoor endurance activities, weight training activities and work done on other rowing simulators.

Product Philosophy: In our first tank we had full size oars and the water depth and tank width to accommodate the standard oars and rigging identical to the boat and quickly learned that was not the way to go to offer a functional and affordable tank. The velocity of water is determined by the strength, endurance and synergy of the participants, mass of water and the wetted surface area of the tank. Our tanks are completely athlete powered. Consequently any measurements obtained from instrumentation is a measure of the contribution by each athlete and data collected is not obscured by external energy input. The Force Measurement Instrumentation

report, shows each athlete’s own contribution to the synergism of the system and the combined system data as well.

To make the tank experience more realistic, we have from the beginning designed the tank to have a scaled down volume and scaled down blade area. We have moved away from rigging identical to the boat to what makes sense for the added drag associated with a tank to a gearing that provides a greater selection of load options and stroke rates.

Dreher Number One In Tank Sales World Wide: We have sold more complete tanks over the years than any other tank manufacturer in the world. In the past three years we installed four tanks outside the USA (i.e., in GBR, CAN & KOR). Since December of 2012, we have installed five tanks of various sizes, with the last one installed in December of 2013. See below for the 16-station tank installed at K-State University in Manhattan, KS in August of 2013:

Athlete Powered Tanks: Our tanks are more environmentally friendly, cost effective, safer to operate and focused to help coaches and athletes achieve improved performance. Powered tanks on the other hand require high HP motors to drive pumps to even achieve a modest water velocity, which we can achieve with our tanks without the extra cost. The flow rates cited for powered tanks are not achievable nor are stroke rates near race pace, because the flow rate dictates the stroke rate. At a given velocity a powered tank feels heavy even if the water looks relatively fast. This is because the large volume of water in the tank traps the athlete in a stroke that cannot be accelerated to the finish. Whereas in the boat the oar handle accelerates to finish. Any mechanically powered tank is more dangerous to operate and therefore must be more closely supervised.

New Product Developments: As we upgrade tank features and functionality we believe it is important to offer an enhancement package that allows existing owners to incorporate new product improvements that we offer on new tanks. The tank feature improvements that have been made over the past several years including: Adjustable Load Extender Arms to provide a greater range of load options, Inner Race Splash shields to provide a more organized and efficient water flow without short-circuiting. See the 2000 vintage Malvern Prep Tank equipped with both enhancements upgraded in 2011 and 2013 (See the top of the next column)

Force Measurement: Equipping a new or existing tank with FM equipment can be a real “Game Changer”! Real-time force measure-ment data: Force curves, gate angle curves and bar graphs of strokeLength showing the amount of slip on both ends of each stroke, watts per stroke per person and per side, total watts generated per athlete per side, stroke rate, water velocity and handle speed help to describeproper rowing technique in a very quantifiable and defensible manner.

Data can be stored and viewed later in detail to conduct a more in depth analysis. The data displayed on the large screen monitor is comprised of curves, bar graphs and numerical data that can show each athlete the consequence of blade work at either catch or release. It also, can show synergism from side-to-side in sculling or between seats in sweep along with the power curve, stroke length and total power per side. Another key piece of data to show efficiency is handle speed and handle acceleration during the execution of the stroke. Testing in the tank setting reinforces what we see with “on-the-water” testing, but in an environment that is more reliable and less time consuming. This instantaneous feedback is clear and unfiltered, reinforcing what the most knowledgeable coaches know intuitively, and is something that can be easily understood by any athlete from beginner to elite.

In Conclusion: As in a boat, the athletes are responsible for the collective, efficient power generation. A “real-time” metrics driven focus helps to simulate the feeling and load during the drive and will allow your rowers and scullers at all levels to become more efficient and synergistic.

An “athlete powered” tank equipped with Force Measurement Equipment is the most cost effective means of achieving high performance off the water and out of the boat!