Introduction:
Dreher has introduced its next generation
Aerodynamic sculls at the beginning of 2012! The
Aero E-H and
Aero E-HX replaced our previous models of
Aero and Aero2. The change was done to offer a more affordable aerodynamic oar to manufacture as well as to ship. In addition, we offer the new design with a blade shape that we have been testing for over two years and that we believe to be more efficient. We have two versions (i.e., standard modulus and high modulus carbon) with the same elliptical designed shaft to provide the aerodynamic effect on the recovery, but with two different price points driven by the materials of construction. The blade shape that we selected for these sculls is what we call the
Hydro or the
H blade.
The Design and Manufacturing Method:
The E-H design draws on 23 years of oar/scull design and carbon prepreg manufacturing experience. The major departure from previous designs is an elliptical aerodynamic shaft and hydrodynamic blade system that is more efficient by optimizing the oar shaft and blade shape as they move through the water and the air.
The elliptical shaft profile blends exactly into the matching blade profile and also assures that the blade pitch will always remain the same. The high-pressure compression molding process results in the same high quality parts that Dreher Carbon Parts are known for. We are able also to produce the elliptical shaft in our roll wrapped construction with a specially designed mandrel. All of our shafts are made on mandrels that allow tape wrapping and most importantly autoclaving. The autoclaving results in superior carbon fiber compaction and resin transfer both of which result in increased longevity of the shafts.
Materials Of Construction Method:
The E-H sculls make use of the same material of construction as standard adjustable length sculls, while the E-HX uses the same materials as our high modulus sculls.
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 maximize the drag type propelling forces that predominate. The last 30° of the drive again trend toward a high aspect ratio shape as lift forces re-establish themselves toward the finish.
This blade shape has a the shape starting narrow closest to the blade/shaft interface and ends up the widest near the tip of the blade. The shape of the blade makes it easy to row with even in rough water. The blade is quiet with little splash at the catch do to a small profile and seamless transition from blade-to-shaft and is quite clean on the extraction.
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.
The elliptical aerodynamic profile is used on the shaft and blade where it will do the most good, toward the end 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:
Less 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 slightly wider shaft where the blade attaches to the shaft, resulting in much more resistance to twist than a circular shaft.
The Integrated Modular Design:
As with the entire family of Dreher Sculls and Oars the Dreher Aerodynamic Sculls, these oars have a true integrated modular design where:
- The blades are installed using low temperature hotmelt requiring no pitching and is removable.
- Based upon the lock and key principle, the elliptical blade receptacle mates to the shaft’s elliptical appendage to fit exactly into the blade. As with all our oars, this transition from shaft to blade is very smooth, and does not generate extra drag at finsih. Some of our competitors have a large step joint at the blade shaft interface that creates excessive drag at the the finish of every stroke.
- The pitch of the oar will remain constant until the sleeve wears out and then it can be easily changed with only a screwdriver.
Testing:
Comparative testing has been conducted using a Force Measurement system at various distances at varying stroke rating over the past two years. Also, subjective testing was done in variable wind and water conditions by different levels of scullers and our feedback to date has been very favorable.
Most of our best feedback has come from our customers. They like to do their own testing and when they convince themselves it is a better deisgn, we are rewarded with additional orders.
However, just as with any of our oars and sculls, the equipment will reward those with the greatest skill.
Conclusions:
These E-H or E-HX sculls seem to make people with good blade-work row faster and this design is worthy of your serious consideration.
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Dreher E-HX Showing Back, Front and Side Views 
Dreher E-HX In Action Just Before the Catch 
Dreher E-HX In Action At the Start of the Catch 
