backs like a pig
 

Back to more questions somewhat related to the Perkins 4-108. This sailboat
is a pig to back up. It really wants to prop walk to starboard. According to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What do
you think?

--
"j" ganz @@
www.sailnow.com

backs like a pig
 

"Capt. JG" wrote:

Back to more questions somewhat related to the Perkins 4-108. This sailboat
is a pig to back up. It really wants to prop walk to starboard. According to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What do
you think?

We have a Perkins 4-154 which had a fixed three blade prop. It also
backed poorly and had a prop walk. We replaced the prop with a Max
Prop (not because of that, but because the noise made by the shaft
spinning when we were under sail sounded like we were next to an
expressway). The Max Prop feathers (doesn't really fold), and the
blades are flat instead of cupped so that it will feather flat. This
meant that the boat backed better - the cupped blades only increase
the bite of the water when going forward. So

Not being an engineer or anything, and not even playing one on TV ...

My guess would be that yes the folding prop would help. Why is it
stored in a locker?



grandma Rosalie

S/V RosalieAnn, Leonardtown, MD
CSY 44 WO #156
http://home.mindspring.com/~gmbeasley/id1.html

backs like a pig
 

Capt. JG wrote:
Back to more questions somewhat related to the Perkins 4-108. This
sailboat
is a pig to back up. It really wants to prop walk to starboard.

Try pulsing the prop when in reverse.

Set engine speed relatively low, then shift into reverse for maybe
5-10 seconds, then back to neutral for maybe 30 seconds.

You will have to experiment with times.

Place rudder in desiored position.

Not perfect, but it will help.

Lew

backs like a pig
 

On Fri, 12 May 2006 10:30:00 -0700, in message

"Capt. JG" wrote:

Back to more questions somewhat related to the Perkins 4-108. This sailboat
is a pig to back up. It really wants to prop walk to starboard. According to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What do
you think?

I swapped a large blade two-bladed fixed prop for a smaller blade Gori
folding prop of the same pitch and diameter. I didn't notice any
change in the walking behaviour. (But the boat sailed faster... )

Ryk


--
NewsGuy.Com 30Gb $9.95 Carry Forward and On Demand Bandwidth

backs like a pig
 

I was in Port Townsend, WA about 5 years ago. Talking to a guy who had
same problem so he called the designer of his production boat. Can not
remember the designer's name but he was someone legendary type.

The designer's response was, "I did not design my boats to sail
backwards."
Bob

backs like a pig
 

Prop walk is a function of 'tip clearance' to the hull and other hull
projections (aperture, etc.) , blade tip shape, , etc. etc. etc.

Just learn to 'back and fill' to steer going in reverse when there is
NO flow over the rudder ... and be prepared to use your rub-rails.
Especially if this is a full keeled boat with an aperture, you will
need LOTS of practice in 'backing and filling' to get it right; but,
once you 'learn', you will not want less prop-walk.

If you want to see exactly how to use prop-walk, go down to the
commercial docks and watch the prop-walk wizards / watermen fishermen
when they are about to land with a single screw boat -- always in a
hurry, LOTS of 'rpm burst', and precise maneuvering ... and all without
touching the wheel !!!!!.



In article , Capt. JG
wrote:

Back to more questions somewhat related to the Perkins 4-108. This sailboat
is a pig to back up. It really wants to prop walk to starboard. According to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What do
you think?

backs like a pig
 

On Fri, 12 May 2006 10:30:00 -0700, Capt. JG wrote:

Back to more questions somewhat related to the Perkins 4-108. This sailboat
is a pig to back up. It really wants to prop walk to starboard. According to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What do
you think?

Prop walk is caused by the design of the boat, mostly the downward angle
of the prop shaft. The more downward angle, the worse the walk will be.
Other factors contribute too, but that's the main one.

Changing the prop may cause a noticeable difference, but not enough to
matter.

Folding props reverse poorly, and won't help. Feathering props, such as
Max-prop's, actually reverse better than fixed props. This won't stop the
walk but it will give you more control.

On some boats I just put the wheel hard over and pulse the throttle, or
goose the tranny in and out of gear. The alternate turning forces cancel
each other, and with luck (and no wind) the boat goes straight back.

Practice!

Matt O.

backs like a pig
 

"Rosalie B." wrote in message
...
"Capt. JG" wrote:

Back to more questions somewhat related to the Perkins 4-108. This
sailboat
is a pig to back up. It really wants to prop walk to starboard. According
to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What
do
you think?

We have a Perkins 4-154 which had a fixed three blade prop. It also
backed poorly and had a prop walk. We replaced the prop with a Max
Prop (not because of that, but because the noise made by the shaft
spinning when we were under sail sounded like we were next to an
expressway). The Max Prop feathers (doesn't really fold), and the
blades are flat instead of cupped so that it will feather flat. This
meant that the boat backed better - the cupped blades only increase
the bite of the water when going forward. So

Not being an engineer or anything, and not even playing one on TV ...

My guess would be that yes the folding prop would help. Why is it
stored in a locker?



grandma Rosalie

S/V RosalieAnn, Leonardtown, MD
CSY 44 WO #156
http://home.mindspring.com/~gmbeasley/id1.html

I guess the owner felt that coming up the west coast he would have more
power with the fixed prop. That was the reason he gave, although I'm not
sure that makes sense.

Thanks for the thoughtful response. I appreciate it.

--
"j" ganz @@
www.sailnow.com

backs like a pig
 

"Lew Hodgett" wrote in message
nk.net...
Capt. JG wrote:
Back to more questions somewhat related to the Perkins 4-108. This
sailboat
is a pig to back up. It really wants to prop walk to starboard.

Try pulsing the prop when in reverse.

Set engine speed relatively low, then shift into reverse for maybe 5-10
seconds, then back to neutral for maybe 30 seconds.

You will have to experiment with times.

Place rudder in desiored position.

Not perfect, but it will help.

Lew

Lew, I'm familiar with this technique. My question was how to correct it
from a mechanical view, not how to correct it by technique. Thanks though.
It's nice to hear the technique mentioned.

--
"j" ganz @@
www.sailnow.com

backs like a pig
 

"Rich Hampel" wrote in message
...
Prop walk is a function of 'tip clearance' to the hull and other hull
projections (aperture, etc.) , blade tip shape, , etc. etc. etc.

Just learn to 'back and fill' to steer going in reverse when there is
NO flow over the rudder ... and be prepared to use your rub-rails.
Especially if this is a full keeled boat with an aperture, you will
need LOTS of practice in 'backing and filling' to get it right; but,
once you 'learn', you will not want less prop-walk.

If you want to see exactly how to use prop-walk, go down to the
commercial docks and watch the prop-walk wizards / watermen fishermen
when they are about to land with a single screw boat -- always in a
hurry, LOTS of 'rpm burst', and precise maneuvering ... and all without
touching the wheel !!!!!.



In article , Capt. JG
wrote:

Back to more questions somewhat related to the Perkins 4-108. This
sailboat
is a pig to back up. It really wants to prop walk to starboard. According
to
the owner, it's got a fixed, 3-blade prop. I believe the boat also has a
folding prop aboard in a locker. Would that help? Would tuning help? What
do
you think?

Rich, as I mentionen in a previous response, I'm familiar with the
technique. I was looking for a mechanical solution. Thanks though.

--
"j" ganz @@
www.sailnow.com