Thrust vectoring
 

Jere Lull wrote:
In article ,
(Gould 0738) wrote:


Something that I've noticed, though I'm not sure if it's universal or
even really true: When I punch it, the prop walk seems to be minor. When
I want maximum prop walk, idle speed is the way to go. It could be just
that the duration is so much shorter, or that the higher thrust
straightens things out.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/


Could it be due to a short duration of a "punch" in reverse, or due to the
factor that sternway (and therefore rudder effectiveness) increased enough at
the higher RPM ? :-)


I've been tending toward that explanation except that a few seconds of
near-idle reverse can slide the transom over a foot without moving very
far; punching it for a few seconds (2000 rpm out of 3600), we don't seem
to pivot at all. When I shift to neutral, we don't have authoritative
steerage way yet.

Our prop (16x10x3 AutoProp) is pretty close to the rudder... Could we be
getting enough flow across it to counteract the walk?

G Take your wife's mixer, turn it on full and plunge it in a bowl of
milk. Basically, all you're going to do is splash milk all over the
kitchen. After you clean up the mess, refill the bowl an put the mixer
in and start it slowly ... no splashing and the milk will start to flow
smoothly i.e. the mixer will be working more efficiently at it's
intended task.
Since i think propwalk is a function of the prop rotation and pitch,
start it slowly and let it work as it is intended and it will do it's
thing and you will get more prop walk right off the bat, unlike you
might when you "punch" it and basically sit there and throw water until
the boats movement catches up to the props speed.
G I know .... totally unscientific, but waddahey.....

otn