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Indoor rowing in tanks is commonplace in some parts of the world - particularly where rivers and lakes freeze in winter. Tank rowing is an ideal way of continuing to keep blade skills up and aerobic fitness practising the rowing and sculling stroke in an indoor environment when the weather precludes outdoors training. It is also a great place to teach beginners and practice technique because the coach can help "position" the athlete correctly, mirrors and video can be used for feedback and there is no concern about the balance of the boat.

Durham Boat Company has worked to create a cost-effective tank design that overcomes some of the design shortcomings of others. Their tank is designed by optimising fluid flow, minimizing fluid volume and proportioning outboard lever and blade size, the water volume of the Durham Boat design is only a fraction of other tank designs. 

Until now tank training at racing speeds and ratings has not been seen as cost effective but the un-pumped design enables good rowing simulations at ratings up to 28 strokes per minute. Alternatively, we can supply a mechanically assisted, moving water option that uses the standard modular designs with modifications.

The most versatile and popular rowing configuration consists of an 8-person sweep tank with two or four pools and configured as in a boat with alternating bowside and strokeside stations. This configuration can be used for sculling with special tank sculling oars. No changes to the rigging is necessary to go from a strokeside stroked tank to a bowside stroked tank or to sculling because all tanks are equipped with two oarlocks for each seat that can be used either sculling or rowing. The footprint of each 8-person tank excluding any room for a walkways on the outside of the tank, is 20.5 ft. x 49.5 ft.

To achieve the correct load for sweep rowing, an oar with a blade area about the same as a standard sculling oar is used. Because, in rowing, we are attempting to move as much water as we can, Durham Boat tanks have a sweep oar that is made with a scull shaft and full sized scull blade with a special sweep handle that will fit into a scull shaft. This enables the higher ratings and better 'feel' than other designs.

The tank has a peak that directs the water flow, but allows spill-over from one side to the other to keep the depth equalised. The design is based upon minimizing the volume of water to be pushed around the tank and having as little friction as possible with the smooth surface and rounded corners. One of the keys to keeping the water volume down was done by scaling the sweep oars down in size. Many historical tanks use a full-sized sweep oar and have a much deeper tank. As a consequence, it takes so much energy and the load is too heavy. What happens is that blades are cut down or made with a wire outline. As the blade area is reduced the resistance is less, but less energy is imparted into the tank to move the water.

In tank rigging to get the lightest load, you have to get the blade tip as close the outside wall to get into the fastest water. This is counter-intuitive to most of our coaches. They are used to shortening the oar length to lighten the load. Another way some of our customers adjust load is with water height and by rowing all 8-sweeps on one side from time to time. The tank has great versatility.
Most of our customers find it too much trouble to change the spread (span) when going from sweep to sculling and will optimize their rig on one or the other. To get the most out of the tank, the proper method is to move the pins wider for sculling. When customers are interested in doing this we have provided a plate with two holes to allow spread/span adjustment.

Our customers are supplied with Macon shaped blades for both sweep and sculling (the sculling blades are cut-down). I think that a narrower blade works best with our design constraint to keep water depth and total water volume at a minimum. We could do a hatchet blade and would have to cut down the inner part of blade and use our narrowest hatchet (Little Big Blade). Also we would have to increase the shaft length.

There are differences in tank rowing, just as there are differences in erg rowing. However our customers find that it is the best off season teaching tool for improving blade skills and blade work, which is the limiting factor in getting one up to speed on the water.

Any size system can be constructed between a one-station reversible sweep tank to a 16-station or more, four-pool sweep/sculling installation. To date, we have installed all sizes from 2-station to 16 station tanks. Our modular design allows for any number of rowing stations.

We work closely with architects, design engineers, on-site facilities people and rowing coaches to insure a complete ready-to-row indoor rowing system. Our tanks are turnkey installations in that we manufacture all of components, ship them to the site and send in a team to assemble all of the components.

Each of the modular tank sections can fit through a man door (i.e., each fibre glass section is 4.5 ft. long and 9 ft. wide). For example an 8-station tank will have two end sections, a dead-water section and eight rowing centre sections. Each section is then bolted together along the common 4" flange and sealed. The rowing unit weldment supports the monorail, seat and foot stretcher assembly and is built in 2 station sections. Load bearing rigger arms are bolted to the weldment so that a walkway can be installed over the rigger.

In order to allow for aisle space, a four foot space should be provided around the perimeter of the tanks. This extra space provides an area for the team to assemble, mirrors, oar racks and access to the equipment to provide periodic maintenance. Site requirements need only compacted sand or gravel for the tanks and a 36 ft. long by 3 ft. wide concrete slab for the rowing unit. If the tank is to be placed on concrete then other site preparation recommendations will be suggested. Our design can be placed in a drained recess or on level floor.

As of January of 2007 Durham Boat have installed 20 indoor rowing facilities of various sizes (2 to 16 stations) for university, high school and club rowing/sculling programs, since we started offering this product.

Detailed specifications of Tank

Our modular size design started in 1992 allowed for any number of rowing stations in a permanent or temporary installation.  By optimization of fluid flow, minimizing fluid volume and proportioning the outboard lever and blade size, the tank volume needs to be only a fraction of that of a moving water tank.  As a result, the capital cost of the installation is much lower and also is the operating cost (no power or maintenance for pumps to move water). 

Fiberglass Rowing Tanks:
The 8-station indoor rowing facility consists of 2 pools constructed of 4 ½’ long by 9’ wide sections, with each section bolted together along the common 4" flange.  An 8-station sweep tank as described above requires as follows:  2 pools; with a footprint of 20.5’ wide by 49.5’ long (1,014.75 sq. ft.).  The tanks including splash shield are about 2.5 ft high.  The depth of the water is about 1 foot deep with each of the four pools containing about 10-11 tons of water.  The tank is, configured, just as in a boat, with alternating starboard and port.   
The tanks including splash shield are about 2.5 ft high.  Each of the bottom sections are 4.5 ft. long, about 9 ft. wide and 1.33 ft. high.  The high and end baffles are approximately 13” high.  High/low baffles go from 13” (17” if including flange) to about 6 inches.  All flanges are 4 inches wide.  All side baffles are 4.5 ft. long except the end baffles, which are about 14 ft. long (semi-circular).  Notches are about 5” wide and 3.5” deep.  The thickness of the bottom pieces will be 1/4”.  The thickness of the top pieces (i.e., splash shields) will be 1/8”.
The modular pieces are drilled for 3/8” bolts at 6-inch centers, pre-assembled to insure proper fit and labeled for re-assembling at the customer’s location.  During installation, an adhesive is used between the flanges to form a gasket, which is bolted together by stainless steel nuts, bolts and washers.  The adhesive and stainless steel hardware are included. 

Centre  Rowing Units:

The base of the “center rowing unit” consists of a primed and powder coated weldment.  The weldment sections are 9’ long and 30 inches wide excluding rigger arms for either of the configurations.   For an 8-unit Indoor Rowing Tank regardless of configuration, 4 weldment sections are provided.  With both configurations, the rigger arms are constructed to act not only as rigger arms (i.e., each station has both a port and starboard arm with an oarlock), but also as a support for a walkways to be supplied by others.  The weldment would have to be lagged to the floor at each station.  Attached to the weldment is a Piantedosi monorail attached with adjustable height foot stretcher (i.e., included are C2 type adjustable foot plates) and sliding seats.   Each seat has two rigger arms equipped with oarlocks and pins for sweep or sculling. 

Tank Oars:
Eight special sweep tank oars and 8 sets of special tank sculls. To achieve the correct load for sweep rowing, an oar with a blade area about the same size as a standard sculling oar is used, while cut-down symmetrical blades to provide the proper load on the tank sculls.