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Old 03-09-2018, 18:06   #46
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Re: Max Prop Issues -cavitation and poor performance

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Doing it in the water is theoretically possible but practically virtually impossible.
Gosh, I wish I'd known that before I did it 50 or 100 times.
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Old 03-09-2018, 18:24   #47
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Re: Max Prop Issues -cavitation and poor performance

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What is the email address for whoever PYI are please?

Last time, a few years ago, when I wrote to whoever about the setting for my three bladed MaxProp I had a very pleasant conversation which got me precisely nowhere. The suggestion to try different settings seemed to overlook the fact that the prop was underwater and lifting a 49' boat is wallet damaging.

BTW, one thing that I can pass on about MaxProp is to only buy the genuine anode. It has a steel plate in it. The cheaper copies fall off in no time leaving just the set bolts. That is because the lugs erode away first.
Thanks, you might have solved my anode issue!
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Old 03-09-2018, 18:48   #48
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Re: Max Prop Issues -cavitation and poor performance

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Originally Posted by Alita49DS View Post
BTW, one thing that I can pass on about MaxProp is to only buy the genuine anode. It has a steel plate in it. The cheaper copies fall off in no time leaving just the set bolts.
There are aftermarket Max Prop anodes that are made this same way. In fact, the Reliance brand cast their Max Prop anodes with a retainer ring long before Max Prop did.
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Old 03-09-2018, 19:11   #49
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Re: Max Prop Issues -cavitation and poor performance

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There are aftermarket Max Prop anodes that are made this same way. In fact, the Reliance brand cast their Max Prop anodes with a retainer ring long before Max Prop did.

I also dab some enamel around the screw holes. Keeps the zinc from getting eaten away there. A bit of extra insurance.
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Old 04-09-2018, 11:04   #50
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Re: Max Prop Issues -cavitation and poor performance

Which feathering props do not require cutting off the prop shaft?
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Old 04-09-2018, 11:19   #51
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Re: Max Prop Issues -cavitation and poor performance

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Which feathering props do not require cutting off the prop shaft?

Hunh? What do you mean? Most that I have seen fit on a standard tapered end with threads.
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Old 04-09-2018, 21:00   #52
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Re: Max Prop Issues -cavitation and poor performance

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Which feathering props do not require cutting off the prop shaft?
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Originally Posted by Suijin View Post
Hunh? What do you mean? Most that I have seen fit on a standard tapered end with threads.
When fitting a Max Prop to an SAE shaft, part of the threaded shaft end must be cut off to accommodate the cone gear. Not so with metric shafts. Not aware of any other feathering props with this issue.

Go to 3:35

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Old 05-09-2018, 03:36   #53
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Re: Max Prop Issues -cavitation and poor performance

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Originally Posted by fstbttms View Post
When fitting a Max Prop to an SAE shaft, part of the threaded shaft end must be cut off to accommodate the cone gear. Not so with metric shafts. Not aware of any other feathering props with this issue.

Go to 3:35



That’s crazy. Ruin the shaft to install a particular prop. Then you can’t carry a spare standard prop and nuts in case you bend a blade on the feathering prop.
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Old 08-09-2018, 15:06   #54
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Re: Max Prop Issues -cavitation and poor performance

There is a good chance that you are over-pitched
Many boats have wrong pitch props.
One Max Prop feature we like (and have used) is that the pitch is adjustable.
In our VP it is easy. Some models need disassembly
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Old 25-01-2019, 16:45   #55
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Re: Max Prop Issues -cavitation and poor performance

Hello all,
Sorry I did not respond sooner - usually I get a notice that someone responded but it did not show up in my e-mail.
Anyway, here are some of the answers to your questions. The engine can hit max rpm of spec 3000. I do not like to run my engine at max rpm and typically stay at about 2500-2600. At these rpms I only get 5.5 - 6 knots with a clean bottom.
I spoke to PYY and they said that the two blade classic was not the correct prop for my boat if I was doing cruising and that I should go to the 3 blade folding (18x14) they wanted $3,000 and would only give me a $200 for mine as trade in.
Flexofold was my real choice but I am replacing sails and electronics and this fixed prop 18x22 came up on craigslist that is right hand rotation and set for a 1.5 inch shaft so I was looking for some input from possibly other Cal 39 owners to see what they have for fixed prop specifications. The engine is fairly new and only has 740 hours on it and runs beautifully.
Thank you all for your input
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Old 26-01-2019, 09:53   #56
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Re: Max Prop Issues -cavitation and poor performance

Our fixed three blade prop (17 in) with (I think 14 pitch) is either too big or or too much pitch. The boat has an old Perkins 4-108 and it will not get to rated full RPM (even if I really don't want to use it that high) and it is supposed to. The engine just reaches 2700-2800rpm and that is all she'll do in calm water with no wind. It also has black smoke which is a good indicator that the prop is not right. There can be other reasons for that but I ruled them all out. PYI and Flexofold gave me recommendations for a lower pitch and they both have a lot of experience specifying props. I felt better that the recommendation from each was the same despite the designs being very different. I went with a four blade Max-Prop for off shore cruising. That would be overkill for inshore. I think highly of the PYI folks. They will give you honest answers based on long experience and a huge number of happy customers.
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Old 01-02-2019, 17:38   #57
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Re: Max Prop Issues -cavitation and poor performance

Well Folks I have news,
after spending 1.5 hours under the boat this morning in <10F weather I discovered something, the PO of my boat had mis-installed the Maxprop Classic 2 blade and made a very reasonable mistake.
Since standard props list diameter and Pitch distance in inches, they mis-interpreted the degrees (as listed by Maxprop for a feathering prop) for pitch in inches and set my Maxprop at 17in. by 16 degrees (9.1 pitch inches) instead of 17 in. by 16 pitch inches (26 degrees). This explains quite a bit regarding the issues I had my first season with the boat related to poor performance.
Talking with PYI and researching this further - this is a standard problem with feathering props because they list the degree angle along with the inches of pitch traveled.
So after talking with PYI regarding what the pitch inches travel should be and what the degree pitch would relate to, and dis-assembling in 8F weather (grease was like wax), I have solved the performance issue and plan on staying with the MaxProp classic 2 blade for a second season but change the pitch inches from 9.1 to 15.7 as recommended by MaxProp.
A very reasonable mistake that took me a week to figure out (not as smart I would like to be)
Best regards
Andy
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Old 01-02-2019, 18:56   #58
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Re: Max Prop Issues -cavitation and poor performance

Excellent, I hope this solves your performance issues.

My only question would be......If you maxed out at 3000RPM with 9" of pitch, what will your max RPM be after adding 7" more pitch?

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Old 02-02-2019, 02:41   #59
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Re: Max Prop Issues -cavitation and poor performance

To be honest Doug
I never went to full throttle (OK call me a chicken turd), I only took the throttle to 3000 rpm (max rating for engine). I understand that with the incorrect pitch that I would have seen a higher max rpm, however after rebuilding 7 sailboats in the last 17 years, most with older engines, I am really conservative about pushing an engine. Additionally my last engine was a Ford Lehman Diesel that cruised at 1600 rpm so revving and engine over 3000 rpm seemed crazy at the time. So I may have been able diagnose potentially this error on the prop set up while on the water, I was not willing to potentially damage my engine in the process (or so was my concern).
Thank you for all your great input. My intent now is to clean up the components of the prop at home and when the weather warms, I will re-install with a pitch degree of 26 and a pitch travel of 15.7 inches.
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