THEORY OF OAR PERFORMANCEgreenspun.com : LUSENET : Open-water rowing : One Thread
WHAT MAKES ONE OAR SHAPE PERFORM BETTER THAN ANOTHER, IE. A SPOON BLADE IS EXPECTED TO GIVE MORE "POWER" AND IS BETTER FOR RACING,AND A LONG NARROW BLADE IS BETTER FOR GENRAL ROWING. IS THE ENERGY THAT IS PUT INTO THE OAR HANDLE CAUSING THE BOAT TO MOVE BECAUSE OF THE MASS OF THE WATER "MOVED" OR "CARRIED" BY THE BLADE, OR BY THE TURBULENCE MADE BY THE OAR BLADE, OR A COMBINATION OF BOTH. (THINK OF THE PERFECT ROWS OF SWIRLS LEFT BEHIND IN THE WATER ON A CALM DAY) I KNOW I'M GETTING INTO PHYSICS AND THEORY HERE BUT I THINK MOST PEOPLE WOULD HAVE AN (INFORMED?) OPINION.
-- JOSH WITHE (FEET.WET@JUNO.COM), February 16, 2002
Josh, There is no simple explanation as to what oar is best or what makes an efficient oar. And to make matters more complex, oar efficiency varies with craft and rower. Get Andy Steevcer's book on the subject from the bookstore at Mystic. There's more that a casual explanation there but if you spend some time with this book you will have a better understanding of what makes a good oar.
-- Jon Aborn (JonEAborn@aol.com), February 25, 2002.
I agree with Jon Aborn that it is a complicated subject. However, I have a Master's in Naval Architecture so I love this stuff.
The quick form of the answer is that fixed seat oars are pretty much just straight drag resistance. You put them into the water and when you pull on them, the water is trying to move out of the way and it creates drag. In a sliding seat boat, the oar actually acts a bit like a wing so there is drag, but there is also lift on the oar blade as it arcs out away from the hull. Hence, these oars tend to "stick" a bit better in the water. The perfect rows of swirls are what are referred to as "tip vortices." Basically, you pull on an oar, one face of the oar has high pressure, the other side has low pressure, the water tries to move from high to low pressure and a vortex gets formed.
As to what makes a "better" oar is pretty subjective. It turns out that physiology has a lot to do with it. Theoretically, the stiffest possible oar with the best bite in the water is best. Problem with the theory is that backs give out in a hurry that way.
This is too long anyway so I'll stop. Let's just stick with Jon and say it's really complicated.
-- Doug Kidder (firstname.lastname@example.org), February 28, 2002.