Indeed. You don't see dimples on the wings of aircraft, for a good
reason...
Graham Collins
CS 36T
On 2021-11-30 3:50 p.m., Dreuge via CnC-List wrote:
On Nov 30, 2021, at 1:47 PM, Doug via CnC-List
<cnc-list@cnc-list.com> wrote:
This is the reason golf balls have dimples. Aides in better flight,
less resistance.
Yes (if spinning) and No (as it adds lateral resistance).
Going with a smooth surface is the overall best approach as it
promotes smooth laminar flow. There are times when a ruff surface
helps maintain laminar flow. For example, the dimples on a golf ball
create a thin turbulent layer which drags air and helps keep the
lamina flow closer to the surface behind the ball. The dimples add
resistance to the flow but reduces the air wake behind the ball which
reduces the overall drag force. The laminar flow around a smooth ball
does not wrap around the back of the ball as well and leaves a larger
wake. The larger the wake, the larger the drag.
I think it would be foolish to add dimples or an orange peel bottom,
unless you have the resources to model and measure the effect for a
particular boat. Maybe adding some aft ruffness as the hull as turns
inward, but this will strongly depend on the individual hull shape and
likely have a positive effect at high water speeds (and a negative
effect at low). Of course, a great way to reduce one's wake is to foil.
Most may recall that dimples of a spinning golf ball help in another
and bigger way by providing lift(i.e. aids in better flight). The
spinning dimples drag air towards incoming flow and drag air away from
the flow on the opposite side causing a high/low pressure difference
(i.e. lateral lift force). This latter effect has not yet been
exploited by sailors. Who knows, maybe we’ll see a spinning belted
keel in the future driven by Kiwi’s pedal power.
-
Paul E.
1981 C&C Landfall 38
S/V Johanna Rose
Fort Walton Beach, FL
http://svjohannarose.blogspot.com/
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costs involved. If you want to show your support to the list - use PayPal to
send contribution -- https://www.paypal.me/stumurray Thanks - Stu
