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posted to rec.boats.building
all thumbs
 
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Default How far should the rudder turn?

I'm wondering if I have the quadrant set up right. At full stop on the
quadrant, looking at the rudder shows it's only turned about 45
degrees. Is this correct? Is that some theoretical limit of effective
angle or something? Thanks.
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jim.blakely
 
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Default How far should the rudder turn?


"all thumbs" wrote in message
...
I'm wondering if I have the quadrant set up right. At full stop on the
quadrant, looking at the rudder shows it's only turned about 45
degrees. Is this correct? Is that some theoretical limit of effective
angle or something? Thanks.


As long as the swing is the same both ways 45 degrees is fine IMHO. Make
sure the travel is smooth, with no binding. I'd only use 'max rudder' for
slow speed maneuvering at low power settings. 45 degrees is a lot of rudder
swing (depending on the vessel).

Is that some theoretical limit of effective.

Not really. A lot of boats don't have that much rudder swing. You may need
ALL of that for some 'backing down' situations when you're trying to
overcome the 'sidewash' of the prop. In reverse the transom always favors
one side (sometimes a LOT). It's better to have more swing than you need.


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Jim
 
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Default How far should the rudder turn?

all thumbs wrote:
I'm wondering if I have the quadrant set up right. At full stop on the
quadrant, looking at the rudder shows it's only turned about 45
degrees. Is this correct? Is that some theoretical limit of effective
angle or something? Thanks.


That would depend upon what you want the rudder to do. . .
Turn the boat? 45 degrees is a good number. Stop the boat, (or keep
the boat from moving after a tack) 45 isn't enough.

I see people trying to tack out of the channel holding the tiller "hard
over" all the time. Often these are the guys who never accelerate after
tacking enough to make it to the other side of the channel.

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Ron Magen
 
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Default How far should the rudder turn?

'Thumbs',

As Jim asked, '. . .what do you want to do?' . If it's a fast turn, it's
actually quicker to 'foot' a little bit for speed, then ease into the turn
and 'meet her' coming out. A *hard* turn to max rudder will actually act as
a 'break' to your forward momentum.

Use some tape and mark 15, 30, and 45 degree locations on your wheel {since
you said 'quadrant' I presume you aren't using a tiller}. Then try tacking
using them, and different entry & exit techniques. Take notes and see which
works best for YOUR boat.

Regards & Good Luck,
Ron Magen
Backyard Boatshop

"Jim" wrote in message
.net...
all thumbs wrote:
I'm wondering if I have the quadrant set up right. At full stop on the
quadrant, looking at the rudder shows it's only turned about 45
degrees. Is this correct? Is that some theoretical limit of effective
angle or something? Thanks.


That would depend upon what you want the rudder to do. . .
Turn the boat? 45 degrees is a good number. Stop the boat, (or keep
the boat from moving after a tack) 45 isn't enough.

I see people trying to tack out of the channel holding the tiller "hard
over" all the time. Often these are the guys who never accelerate after
tacking enough to make it to the other side of the channel.



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Terry K
 
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Default How far should the rudder turn?

Just yanking the tiller over may
serve some, but a sensitive analysis of the dynamics can be
educational. Instead of horsing the tiller, one moves it smoothly,
feeling it's bite in the water so that it is never stalled, using the
foreward momentum acting on the rudder to convert boatspeed efficiently
into angular momentum, one is then apropos actually able to contribute
to accelleration once the head is around, by coupling the rotational
momentum back into the boatspeed, by using the tiller skillfully as a
wing so that once the boat is turning, carefully considered control of
the tiller ensures that it's sideways motion is translated into
foreward thrust instead of stalled drag. It's a seat of the pants
thing, kind of related to driving a car smoothly as opposed to jerking
the wheel around until everyone is carsick.



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Chris
 
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Default How far should the rudder turn?

If you want to see how much 'angular momentum'
a boat does store, let the tiller go in the middle of
what would be the sharpest turn you can manage
and see how much further it turns.
Them long hulls is built for going forward, not for
spinning.

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Chris
 
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Default How far should the rudder turn?

(Not knowing the boat) I would gess that 45 degrees is plenty. I have a
tiller, which would allow 180 degrees, and I think I rarely ever use
more than 30.

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derbyrm
 
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Default How far should the rudder turn?

Most foils stall at between 15 and 20 degrees angle of attack. Of course
that is measured from the chord of the foil to the fluid flow, so when the
boat is rotating the flow is across the transom rather than along the keel.
Once the blade stalls, you could pretty well replace it with a bucket or sea
anchor.

Someone mentioned prop wash. I must admit I keep thinking sail boats.
Prop wash, engine thrust, there may be reasons for turning the rudder
further, but it would be for low speed maneuvering. (???)

Roger

http://home.insightbb.com/~derbyrm

"Chris" wrote in message
ups.com...
(Not knowing the boat) I would guess that 45 degrees is plenty. I have a
tiller, which would allow 180 degrees, and I think I rarely ever use
more than 30.



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Terry K
 
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Default How far should the rudder turn?

My boat has short bilge keels and will happily spin around until it
drills a hole in the water.

I can feel the coupling I mentioned earlier, and if you have a boat
which turns easily, you might too, if you are not er, "insensitive."

My HR28 had a relatively short keel, and it too reacted in the same
way.

I built a wheel steering system from sewer pipe etc for it, and had
about 45 degrees deflection, as I do comfortably with the tiller on the
Tyler 29, and hardly ever need or needed to use full deflection.

The rudder is actually a brake. We steer the boat by adjusting the
sail balance and trim.

Both had counterbalanced rudders, and neither would hold a course
unless very carefully set up in steady conditions and only with the
tiller or wheel lashed. If either started to turn and was let go, it
would just about screw itself right down into a whirlpool.

Management of angular momentum is something to learn, like feeling the
groove, but is more delicate.

Terry K

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derbyrm
 
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Default How far should the rudder turn?

Exlaxly.

Roger

http://home.insightbb.com/~derbyrm

"Chris" wrote in message
oups.com...
Management of angular momentum is something to learn, like feeling the
groove, but is more delicate.

Terry K


Just as physics?



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