Weight adjustment for boat types other than eights?

[GigJaxk]

Hi,
We row Cornish gigs which are 6 man + cox fixed seat craft with pins rather than rowlocks.
Any ideas on what we should make the adjustment for these heavier, less efficient craft?

[jamesg]

What do you want to adjust?

A crew 20% heavier might be able to pull 20% more power, which using the cube law suggests about 6% faster.

[GigJaxk]

Thanks for the reply, I read in other areas of this forum that the adjustment ratio isn’t quite right for other craft other than an 8. I figured given the relative weight and displacement of a Gig over a sliding seat 8, the adjustment ratio would need to be altered. Truth is I have no idea by how much, or if at all, so was looking for some ideas.

I’ve been using the equation shown on the concept 2 website:
https://www.concept2.com/indoor-rowers/ ... calculator
Figured this should be adjusted based on the craft.

[jamesg]

the adjustment ratio isn’t quite right for other craft other than an 8.

If you use the calculator on your crewmen's single Concept2 erg times, you'll get a set of times that refer to an eight, adjusted for their weight. Which presumably is what you want, faster means better. These times have nothing to do with other boats, which will all be slower than an eight.

NB, the C2 ergometer also shows Watts. So if you have your crew's single Power and Weight data for some standard distance, relative to gig racing, just divide W/kg to see what they are doing. You may have to correct weight data for some standard height based BMI, however calculated.

On the erg there's a slide, and the prefered technique uses it, since shells have slides too. Do you use the erg with a fixed seat for gig training and TTs?