By Mark Mills, a prominent sailor and yacht designer, on hull shapes
and drag issues. Nice overview.
Very interesting, so I awaited comments. And I waited......
Actually, I think the article was confusing & bitty.
It ignored the bugbear of shell design - the fluctuating velocity -
while making passing reference to pitching. WRT pitching, it appeared
to favour a more flared bow section
It left the reader confused on wave drag. It said wave drag was tiny,
so surface area should be reduced bringing shorter hulls: “If you do
something that increases your wetted surface by one square foot you
better be good because that is a price you will be paying.” It got into
a bit of a knot over semicircles without explain what stopped us from
using hemispherical hulls. And that came after noting Lazauskas &
Tuck's evidence that wave drag, while relatively small, did matter &
indicated longer hulls with inevitably higher wetted surface: "their
work suggested that even longer and crucially narrower hull shapes than
currently popular theoretically appeared to be the way forwards".
It mentioned the effect of beam on stability, then advocated removing
the rudder. Did it mean removing rudder & fin? The fin enhances roll
stability, while the varying effects of wind & imbalances of
individuals' rowing forces affect steering at all times. A very little
yawing off-line will cost far more in parasitic drag than the possible
drag of the decent steering foils which would keep the boat straight.
There was worthwhile mention of aerodynamic drag; sailors know well
that you get a faster boat through lift enhancement & drag reduction.
We rowers know we go slower into a headwind, but ignore all known ways
of meaningfully reducing wind drag (e.g boundary layer trips on
oar-shafts) & do nothing to address the other sources of windage.
I'd be interested to know which "recent shell designs appear to be
looking to exploit new solutions". Don't think we saw any of that in
the last Boat Race.
Maybe the problem is that you can't cover any of that meaningfully in a
few hundred words?
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Email: ca...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)
We were all waiting too. For you :-)
> Actually, I think the article was confusing & bitty.
I too was confused, not that I know much about hull design, but if the
intention was for me to know more about it when I'd finished reading the
article pretty much failed.
Nor was I any the wiser about what, if anything, the author was
advocating as a response to the various factors outlined. Disappointing.
Henry Law Manchester, England
Wasn't this article on-line last year? Or something very very
similar? I seem to remember reading something on boat design by a
yacht designer on the boat race website last year. I seem to remember
not being very impressed with it then.
This article only showed up on my computer on April 2. If that
happened elsewhere, it might explain the wait.
I'd kind of expect flared bow and stern sections above equilibrium
waterline to be an advantage, since they seem to be forbidden by the
no-convex-hull-sections rule. I'm pretty sure that the extra drag of a
directionally-stable hull shape would cost more than a proper fin. A
drop-in rudder might very well be worth trying.
Me, I'm fixing up my Frontrower. Nearly hit a swimmer last year.