Dreher introduced its next generation Aerodynamic
sculls at the beginning of 2012! The Aero EH
and Aero EHX
replaced our previous models of Aero and Aero2
. The change was done to offer a more affordable aerodynamic oar to manufacture, a full 10 centimeters of handle adjustment and less expensive to ship.
Dreher is adding to its blade shape offering for Aerodynamic Sculls with Aero EA and EAX The blade is cross between are Apex shape and the original Aero Shape and was first shown at the 2013 HOCR. It is almost identical to the blade on the original Aero sculls, which had strong following. The blade shape will be appreciated by people who learned how to scull with the hatchet blade shape. Anyone that likes the Apex or the original Aero Shape will like this blade.
Now we have two blade design at two different price points driven by the materials of construction selected (i.e., standard modulus EH and EA and those two blade shapes with high modulus carbon: EHX and EAX). Both are on the same elliptical designed shaft to provide the aerodynamic effect on the recovery. Now that we have two blade shapes from which to select, be the first in your club to purchase either of these new sculls!
The Design and Manufacturing Method:
Both the EH and EA design draws on 25 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 EH and EA sculls make use of the same material of construction as standard adjustable length sculls, while the EHX and EAX uses the same materials as our high modulus sculls.
Hydrodynamic Advantages of EH or EHX:
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.
Advantages of EA or EAX:
For those people use to the hatchet shaped blades, these blades will feel familiar and easy to use row with even in rough water. The blade is quiet with little back splash at the catch. Both blades styles have the same smooth blade-to-shaft transition and all have clean extraction. These blades will perform best when used shorter as the attack and angle is designed for a shorter inboard setting.
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.
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 or the customer can request an epoxy adhesive, where the blade and shaft can no longer be replaced separately if one is damaged.
- 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 finish. Some of our competitors have a large step joint at the blade shaft interface that creates excessive drag at 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.
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 design, 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.
This entire family of aerodynamic sculls seems to make people with good blade-work row faster and this design is worthy of your serious consideration. As with all oars: A late square up quick vertical speed of entry is desired for best performance.