Pin diameters and pitch insert colours

[Stewie]

Does anyone have a source of information that correlates different sculling/sweep pin diameters to countries and to the colour of swivel pitch insert that suits them?

E.g. 13mm - UK/EU typical sculling pin - blue inserts

And so on?

Related Can anyone tell me the diameter of pin used in a typical US sculling boat, which requires white pitch inserts?

Thanks
Stewie

[2potsin...@gmail.com]

I don't know if there is an international color scheme or country-based color scheme, but it you are using a Concept2 oarlock, the manufacturer's color scheme for sweep oarlocks is: black-9/16 inch pin, blue-13mm pin, white-1/2 inch pin. For sculling oarlocks, the color scheme is: black-1/2 inch pin, blue-13mm pin, white-7/16 inch pin.

As for "typical US sculling boat," there is no "typical." Each manufacturer decides what size pin they want to use and the corresponding pitch insert is installed. In our fleet, the Peinert singles are all 1/2" black inserts, the Hudson doubles are all 13mm blue, and the Vespoli quads are 7/16" white.

[carl]

One thing that disappoints me is the trend towards 13mm diameter pins
for scull and sweep - "'cos it's convenient".

Why? the amount of bend on a cylindrical bar under a given load is
proportional to the cube of its diameter. That makes the 9/16"
(14.28mm) pin 33% stiffer than the 13mm pin.

Obviously rowers want the most rigid possible pin alignment. And their
greatest force is applied around mid-stroke (when the magic of the
backstay/topstay has limited effect), so the trend towards 13mm pin for
sweep and scull is neither well thought out nor smart.

Similarly, the 13mm scull pin is a whole 60% stiffer than the 7/16" pin

We make very stiff riggers, we value that stiffness (which exceeds that
of the pin - especially when the rower has the oarlock near the top of
the pin - so it is disappointing to encounter pressure to switch from
9/16" to 13mm for sweep pins just because a major oarlock maker may have
dropped 9/16" bushes from their inventory (if indeed they have?).

It gets me wondering how many engineers we still have in rowing. As a
sailing friend said to me not long ago (and I paraphrase slightly), "You
rowers work so much harder than we do, but you'd go faster if only you
took the trouble to understand the engineering science behind what you do"

Cheers -
Carl

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[madmar...@gmail.com]

Bushing Color Sweep Scull
Black 9/16 in 1/2 in (and adapter*)
Blue 13 mm 13 mm
White 1/2 in 7/16 in



The table doesn't quite line up, but I think you'll work it out.

Copied from http://www.concept2.com/service/oars/pitch/adjusting-pitch-with-bushings.

If the boat is from the last 15 years then it is probably 13mm. I can't think of the last time I had to deal with the older size pins (especially the white bushings).

[andymck...@gmail.com]

Carl

I'll bite - my 'back of google' calculations suggests that for a sculler the difference in 'give' is 0.25 mm; a deflection of about 0.5 mm for a strong sculler on a 9/16" pin, against maybe 0.75 mm on a 13 mm pin, generously assuming the centre of force is applied 150 mm above the attachment to the rigger. I can accept that some rowers fetishise rigidity, though i'll still argue that a little pin flex acts as a mechanism to assist clean entry/extraction while maintaining blade depth though the middle of the stroke. While at mid-stroke the geometry isn't perfect for a topstay, it should still help resist the bending to some extent. If you bring the centre of pressure down to within 10 cm of the attachment the difference in stiffness starts to be so small you can hardly see it - 1/10 of a mm?

The 9/16" pins will also add 60 grammes of weight to the boat! That is the equivalent to forgoing 3 and a half chocolate digestive biscuits before each outing!