RandallFoil

[Stelph]

There is an ongoing discussion of the RFs on rec.sport.rowing, with some interesting points and evidence. I wasn't sure how to pose my question there, so I'll try here.

What if we turned the question around. Evidence of massive, 5%, speed gains looks shaky, more like fool's gold. But the tests don't suggest that the RFs make you slower, mostly no difference. Perhaps "RF's don't slow you down" is not a good marketing slogan.

Its a good question, but to focus on one part of it - are we sure that the foils don't slow you down? The profile of the foils when feathered increases the surface area during the recovery at the point where the blade is travelling the fastest (i.e. the spoon) - Concept confirmed from testing that a decrease in shaft width decreased drag so it is not too much of a leap to predict that an increase in spoon thickness would cause an increase in drag. The most recent public testing showed slower times, specifically time into a headwind without foils matched times in calmer conditions with foils, but this is just one test so not to be taken as fact

https://analytics.rowsandall.com/2019/0 ... all-foils/

Yes I realise this was done with 4 degrees pitch, I still can't quite see how such a small change in pitch would have such a massive difference in the performance of a blade, but further testing is expected to come with adjusted pitch which will be interesting

But they may prevent some technical flaws at the catch/entry in less skilled rowers. For example I worked for years to maintain relaxed shoulders at the catch, to avoid taking the catch by engaging too stiff shoulders. I've mostly fixed this bad habit but will admit that it returns sometimes at higher stroke rate. I quickly recognize the problem by digging at the catch. Fixing this technical problem also eliminated nagging shoulder pain.

So here's my question: will the RFs fix problems in technique that encourage diving at the catch or do they allow you/me to continue poor technique without the negative effects at the catch?

Id agree with you that I think this may be where the potential benefit comes from - we all know erg monkeys with monster 2k's who cannot move a boat for love nor money, there is a technical aspect to rowing that means only a percentage of what you can pull on an erg can be applied on the water, for the more technical that percentage is high, for others it is lower. My theory is that for those who have a lower percentage/less confidence sculling the foils act to balance, and so help increase the rowers confidence and allow them to input a higher percentage of their total power - that would explain why some report massive gains, yet telemetry testing at matched power input fails to show any benefit in boat speed etc. That does make it harder to test with telemetry, and means only some would see the benefit which you could only check by testing a set

[Stelph]

Slight edit

Field testing - Currently underway, marketplace continuing to challenge the yet unproven claim of 5% speed gain, or roughly 20 seconds over 2K for elite 1x ,testing using matched power and telemetry unable to demonstrate benefit of foils, claim that 1 degree pitch change would demonstrate benefit, to be tested

[KitD]

Hypthosises - The application of a hydrofoil will restrict blade depth and have a positive influence on speed

Are RandallFoils hydrofoils? The blade itself acts as a foil, ie creating lift. But AIUI RandallFoils are extensions that separate the low and high pressures on each face of the blade, a bit like a wing tip on an aircraft wing. They don't create lift per se.