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Dreher Aero Oar and Scull Designs

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The Dreher Aero design has been in development for nearly two years and is a totally new oar for 2009. The Aero is a truly revolutionary oar with regard to the design, manufacturing processes, and even the type of carbon used. It is a radical departure from current oar production methods. The result is the first oar that attempts to overcome speed decreases on the recovery. These are due to air resistance on the oar shaft and blade as they both move in the same direction at maximum boat and oar shaft velocity. The result - a shaft shaped like an aerofoil.

The Design

The Aero draws on Dreher's 20 years of oar/scull design and carbon manufacturing experience. The major departure from previous designs is an aerodynamic shaft and hydrodynamic blade system that tests to be more efficient by optimising the oar shaft and blade shape as they move through the water and the air.

The aerodynamic shaft profile fits exactly into the matching blade profile and assures that the blade pitch exactly matches the sleeve pitch. The result is perfect repeatable pitch, oar to oar. Our manufacturing method allows for a moulded seat for the sleeves that further ensures perfect pitch from the sleeve to the "lock & key" blade attachment.

Manufacturing Method

An aerodynamic shaft profile required a new manufacturing method, to reduce drag on the shaft. The result is a smooth continuous aerodynamic shape. Moulding to control the outside shape of the shaft rather than to the inside diameter allows location contours for a sleeve "seat". These contours in the sleeve area are unlike any that are possible on present roll-wrapped oars.

Sleeve locating contours, designed as an integral part of the tooling, allow the sleeve to be easily installed and, when worn, the sleeve can be replaced with no adhesive. This means that to change the sleeve (collar) you just unscrew and remove the sleeve and screw a new one in place. A 5 minute job.

No pitch checking is ever required with the Aero oar and scull design. By integrating the sleeve “seat” into the total oar design it guarantees that the sleeve is correctly aligned with the spoon.

Hydrodynamic Advantages

Hydrodynamic theory and racing blade performance models shows a high component of lift propelling force at the catch position. This recommends a high aspect ratio blade shape. When the shaft is 90° to the axis of the boat a bigger area would theoretically be best to maximise the drag type propelling forces that predominate. The last 30° of the drive again trends toward a high aspect ratio shape as lift forces reestablish themselves toward the finish.

Ideally, to optimise the blade size you would require a variable sized blade. The Aero blade/shaft system is as close as one can come to an adjustable area blade when the blade is buried deeper at mid-stroke. Here the foil section of shaft can act as an extension in blade area to the shaft.

The hydrodynamic blade shape seamlessly combined with the aerodynamic shaft results in the water not being able to distinguish where the blade ends and the shaft begins.

The blade is exceptionally quiet with little splash at the catch caused by the small profile and seamless transition from blade-to-shaft.

Aerodynamic Advantages

A true aerodynamic profile seamlessly mated to a hydrodynamic blade profile provides for the ultimate in wind resistance on the recovery when the boat speed and the oar’s angular velocity are both at their maximum and in the same direction.

The aerodynamic profile is used on the shaft and blade where it will do the most good, toward the end of the recovery where the angular velocity is the greatest. The aerodynamic profile offers the least resistance at the time when the boat is traveling at it’s fastest – on the recovery, when the oars are out of the water.

Performance

Lowered wind resistance on the recovery and improved stability equates to the potential for greater speed for the same effort. The more efficient the sculler and the faster the boat class, the greater the potential for speed improvement.

A side benefit of the aerodynamic shape is a thinner, but much wider shaft where the blade attaches to the shaft, resulting in much more resistance to twist (torsion) than a circular shaft.

Variable blade area provides the potential for greater speed potential through the water.

Specifications

Two shaft stiffnesses - standard and less stiff (soft)
Red SRS sleeve with Black collar
Two handle sizes - medium and small
"Row-Wik" grip wrap or Stampfli grip
High modulus prepreg carbon construction
Each scull will weigh 1.25 kgs (the lightest of our range)
Length adjustment +/- 5 cm
Adjusts under sleeve - the strongest part of the oar and close to pivot point
100% pitch guarantee
Seamless blade:shaft transition

Timescales

The Dreher Aero Sculls are available now; the Dreher Aero Sweep Oar will follow in Spring 2009. Demonstration Sculls and Oars will be available for our customers to try. Register your interest by emailing us your details for future updates.