The Secret of Blade Type and Gearing

Susan submitted this question about oar length:

I just received your “Nuts & Bolts guide…” from Amazon.com I bought the book because I’m getting alot of conflicting feedback about my rigging.
When I learned to scull, it was in a VanDusen racing 1x with club rigging: 160 spread, 289/88 C II big blades. My technique is good, but I’m not very strong (hence the reason why I work technique). I now own a 2004 Hudson LWT 1x. I have not been able to use these same rigging settings on my Hudson. I cannot get to the pin to save my life.
I’ve been playing around with measurements. I still have a 160 spread, but had to shorten my oars to about 287 with an 87.5 inboard on C II smoothies. I’m almost at the pin, but the boat is feeling heavier.
I looked at the chart in Chapter 15 of your book and I have to say that I’m even more confused. I’ve never seen scull lengths over 290. In fact, when I looked at Volker Nolte’s charts (Rowing Faster) and at the recommendations given for Fluidesign, they had me moving the oars shorter, citing a difference between the CII smoothie and big blade sculls.
What’s a good length and does the particular blade type make a difference?

Susan:

A great question. There certainly is a relationship between blade type and oar length. The physics of why can be tedious, but if you would like some insight into how blade shape, design, and length all work together you may want to check out this page.

Back to your question . . . as blade shapes have morphed into new shapes, blade lengths typically have shortened. In your case, going from a CII Big Blade to a CII Smoothie, you should shorten your blade only about 1 cm or so. Now this is based on CII’s testing, and is just a guideline. It looks like that is what you did. Please refer to the chart below for some guidance.

Here is the secret of selecting the correct rigging adjustments for you—testing. Slow, methodical testing can get you where you want to go. I would suggest that where you are now with your lengths might fine, and your inboard seems okay. I would not go any wider with your span (you are at 160 now). I would suggest that you might try testing your work-through.

01-07-13 - oar length guidelines.jpg

I have noticed that scullers seem to have difficulty finding the right work-through measurement for them. (This is the distance from a perpendicular through the pin to a perpendicular across the front stops.) Scullers tend to need negative work-through with their hips at or behind the pin.You can make this adjustment on the water by moving the footstretchers. (Please refer to the book for more into on this).

Here is what I would do (on a no- or low- wind day).

  1. Set up a SpeedCoach for average pace (the average is taken from the moment you hit “Start” until you hit “Stop”. You can use GPS. More on that in a later post.
  2. Row 300-500 meters
  3. Take average speed of piece
  4. Make slight adjustment to footstrechters
  5. Row and average piece again
  6. Repeat a few times with small adjustments
  7. Compare averages of each piece, noting footstretcher placement

This information should give you some insight into your hip placement against the pin. Also, record how you “feel” after each piece. These subjective evaluations are also important for someone who has rowed as long as you.

Try this and let us know what you come up with.

Readers, anyone want to pipe in for suggestions for Susan?