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-   -   Prop walk with a Max Prop (http://www.sailnet.com/forums/gear-maintenance/4981-prop-walk-max-prop.html)

ikent 09-10-2002 07:40 AM

Prop walk with a Max Prop
 
I recently purchased a Max Prop for my ketch and am still experiencing substantial prop walk. I bought it mostly for the improved speed while under sail but was expecting a decrease in prop walk as well. Has anyone else had this experience? If so, was there a solution?

thx
Ike

Sailmc 09-10-2002 09:47 AM

Prop walk with a Max Prop
 
Don''t know what your problem coould be. I went from a 36'' boat with a folding prop to a 43 with a 3 blade MaxProp and there was a huge reduction in prop walk. I back the 43'' into places I would never have dreamed of trying with the 36''. The only thing I can think of is that you might be overpitched. I also developed the the habit with the 36'' of giving the throttle a good shot of reverse to get the boat moving and then backing off after it starts to move. I do this with the MaxProp and it works beautifully.

ikent 09-10-2002 04:45 PM

Prop walk with a Max Prop
 
I''m confused also, I went from a 3 blade fixed to a MaxProp (at a considerable premium) and expected to see some change but no luck. Thanks for advice (gun n'' coast) have tried it as I used to do with fixed blade but she is really walking before I''m making sternway. re: pitch, based on the boat''s performance in forward I am underpitched and need to increase it (PYI concurs with this assessment). Still confused but will have to re-assess after pitch change.

Thanks for the advice sailmc.

WHOOSH 09-14-2002 05:34 AM

Prop walk with a Max Prop
 
Ikent, what performance improvement did you find under sail with your Max Prop? (Did you measure this in a controlled enough fashion to feel some certainty with the measurements?) And who are you working with at PYI - Frederick? How''s the after-sales support you''re getting?

I ask because you''re ahead of me but I may be following the same path. Thanks!

Jack

JEFryar 09-15-2002 11:09 AM

Prop walk with a Max Prop
 
I''m confused. What ever happened to recognizing the characteristics of your vessel and using them to your advantage?
Sailorat50

windship 09-15-2002 11:16 AM

Prop walk with a Max Prop
 
Are you getting proper rpm''s? Does your engine smoke eccessivly since the change? Can you have a different pitch in reverse? Is the angle of your prop shaft at an extreme angle to where the prop wash is forced up against the underbody?

Dennis

EscapeArtist 09-17-2002 05:54 AM

Prop walk with a Max Prop
 
I love prop walk. It lets me manuever the boat in ways that I could never duplicate if it were significantly reduced.

For example, most single-screw boats will turn left inside their own length, because of prop walk effect.

Rather than spending two thousand bucks on a propeller, Drop $20 for Chapman''s and read the section on boat handling under power. Make it work for you.

svindigo 09-17-2002 08:34 AM

Prop walk with a Max Prop
 
Thanks all for the responses - Please note I didn''t say I couldn''t manuever. I do work with the characteristics of the boat. I am seeking to understand why the more common experience of reduced prop walk with this prop was missing in my case. To answer a few of the questions, my pitch is the same in forward and reverse although PYI suggested that they could remachine the hub to give differing pitches. We''re not going down that road because I can maneuver the boat just fine. The angle in relation to the underbody is not extreme but my shaft resides in an underbody fairing that could be causing the "push". Sailing performance has been enhanced relative to the old fixed blade prop by about .5-.75 knots by our notes when sailing in 12-18 knots depending on point of sail. PYI service has been exemplary and I have worked with both Frederick and Kevin. They are both valuable sources of information.

Thx
Ike

RichH 09-17-2002 09:08 AM

Prop walk with a Max Prop
 
Prop walk has as much to do with tip clearance from the prop to the hull, and the hull configuration (shape of aperture, skeg. etc.) where the prop wash impinges.
So if you want to reduce prop walk, consider to reduce the diameter of the prop and change the pitch. If you can master ''backing and filling'' when going astern .... you''ll eventually actually desire MORE propwalk.

awaghorne 05-24-2011 01:14 PM

Prop
 
I noticed a mention of excessive smoking when discussing the props. I have a s/v Gulfstar 36 with a prop that has no markings. At the higher end of the RPM range I get backwash on my transom of un burned fuel. At about three quarter RPM very little is on the transom.

My mechanic says no problem run the engine. Tired of cleaning my rear end.

Am I missed proped?

Thanks in advance.


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