Benefit of Radius on leading edge?

[Strainer]

I'm thinking of putting a radius on the leading edge of my 20 year old Crokers. They came with squared edge but have worn down some over the years. Any benefits? Any pitfalls?

Strainer

[carl]

On 03/03/2022 04:42, Strainer wrote:
> I'm thinking of putting a radius on the leading edge of my 20 year old Crokers. They came with squared edge but have worn down some over the years. Any benefits? Any pitfalls?
>
> Strainer
>

Makes sense.

There's never any advantage in having square edges to an oarblade -
beyond it being easier to manufacture that wsy. An oarblade acts as a
'foil', moving within the water at different speed & along different
axes at different parts of the stroke, so any of its edges may at
different times become a leading or trailing edge to that flow. Sharp
corners on leading edges encourage flow separation, which you don't
need. Since the angle of attack will vary as considerably as the flow
across any edge, optimisation is not possible & the best compromise, in
order to optimise performance, will be to radius all edges.

Cheers -
Carl

--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
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[Strainer]

Carl,

Thank you for your quick response. I'm hoping to gain a little speed from the lower resistance to water flowing over the leading edges (and maybe even a little less drag when feathered during recovery). Likely not significant or measurable with a stopwatch...

Strainer

[carl]

You'd probably reduce aerodynamic drag more by adding trip-strips to the
oar-shafts, helping to induce better boundary layer attachment on the
trailing side of the shaft & prevent formation of a more turbulent wake.
But any measure that reduces aero drag is worthwhile (as long as it
doesn't come with unintended consequences), while enhancing flow over
the blade surface during the early and later phases of the stroke makes
good sense.

[James HS]

why doesn't anyone do that?

estimates of 0.1% advantage (2 metres) in calm conditions seem worth pursuing?

Are there details of what they should be like - I am a bit curmudgeonly and tend to like to try thing out :)

James

[James HS]

Found a product called Turbulator tape and will have a go at fixing to my sculling blades :)

[Strainer]

James, how did it go with the Turbulator tape?