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Old 13-07-2015, 23:28   #1
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Proper Prop pitch for Maxprop

Need information from cruisers with experience on setting Maxprops.

I have a 20,000 lb 42ft US Yacht with a 14ft beam 32.5 Water Line with a 17" Maxprop. The engine is a Perkins 4-108 with 50HP driving a Hearth 2.5:1 transmission. I would like to know the pitch to set the Maxprop for cruising offshore.

Thanks, Jim
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Old 13-07-2015, 23:43   #2
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Re: Proper Prop pitch for Maxprop

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Originally Posted by boatrips View Post
Need information from cruisers with experience on setting Maxprops.

I have a 20,000 lb 42ft US Yacht with a 14ft beam 32.5 Water Line with a 17" Maxprop. The engine is a Perkins 4-108 with 50HP driving a Hearth 2.5:1 transmission. I would like to know the pitch to set the Maxprop for cruising offshore.

Thanks, Jim
Ask PYI http://www.pyiinc.com/

Address: 12532 Beverly Park Rd, Lynnwood, WA 98087
Phone425) 355-3669

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Old 13-07-2015, 23:46   #3
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Re: Proper Prop pitch for Maxprop

If you email, call, or stop by the people at PYI they will tell you exactly what is correct for your setup.


-- PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D --

I emailed them last year with my details and they got back to me fairly quickly with the info.
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Old 14-07-2015, 00:17   #4
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Re: Proper Prop pitch for Maxprop

Remember too, PYI can recommend a diver to do the repitch while the boat is in the water. No need to haul for this.
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Old 14-07-2015, 09:35   #5
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Re: Proper Prop pitch for Maxprop

We just had our maxprop rebuilt by PYI. They did an excellent job and were super easy to work with. It came back looking like new. There is a photo of the before/after in our album on CF and FB.


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Old 14-07-2015, 10:00   #6
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Re: Proper Prop pitch for Maxprop

Whilst PYI offer an excellent service, their recommended pitch does not take account of the age of the engine. We have a 48ft Wauquiez, with a 100hp Yanmar. The engine was overheating at 2500 rpm, we reduced the pitch to 18 degrees, now it is perfect.
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Old 14-07-2015, 10:02   #7
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Re: Proper Prop pitch for Maxprop

Adding my kudos for PYI. We bought one for them years ago for out Pearson365. Their instructions were very succinct, but when we did need help on the pitch question they were able to help us over the phone.

Currently saving up for my next Maxprop - 26 inches. Ouch.....this is gonna hurt.
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Old 14-07-2015, 10:13   #8
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Re: Proper Prop pitch for Maxprop

PYI is absolutely tops...but in my experience they tend to make recommendation that are over pitched. e.g for my boat with a Volvo 2003 them recommended 22*, but the correct(?) answer for me was 18*.

So take their recommendations with a grain of salt. It might be helpful to go to your owner group web site, if there is one, and ask what experience others have had.
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Old 14-07-2015, 10:17   #9
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Re: Proper Prop pitch for Maxprop

Any recommended pitch is just a starting point. Set it to the recommended pitch, get some sea time and if required change the pitch to fine tune it.
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Old 14-07-2015, 10:24   #10
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Re: Proper Prop pitch for Maxprop

Here is a link.

Propeller Recommendations from Yanmar at Marine Diesel Engine from Torresen Marine's Marine Diesel Direct
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Old 14-07-2015, 10:51   #11
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Re: Proper Prop pitch for Maxprop

If a boat with a healthy engine and a clean hull cannot reach maximum governed engine speed, then it is over-pitched. That's the bottom line.
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Old 14-07-2015, 11:37   #12
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Re: Proper Prop pitch for Maxprop

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If a boat with a healthy engine and a clean hull cannot reach maximum governed engine speed, then it is over-pitched. That's the bottom line.
.

It ain't necessarily so. The 4108 max governed speed is 4000 rpm--WAY TOO HIGH! That was done so marketing could call it a 50 hp engine. However, at over 3000 rpm the engine is incredibly noisy and leaks twice as much oil.

In reality it is a 35 hp engine, and is happiest cruising about 2500 rpm with WOT of 3000. If you are long distance cruiser and primarily motor when the winds are light, you can improve noise, vibration, fuel mileage and oil consumption by 'over-pitching' the prop. I started at the recommended pitch and increased it twice over 10 years.
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Old 14-07-2015, 13:07   #13
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Re: Proper Prop pitch for Maxprop

Quote:
Originally Posted by boatrips View Post
Need information from cruisers with experience on setting Maxprops.

I have a 20,000 lb 42ft US Yacht with a 14ft beam 32.5 Water Line with a 17" Maxprop. The engine is a Perkins 4-108 with 50HP driving a Hearth 2.5:1 transmission. I would like to know the pitch to set the Maxprop for cruising offshore.

Thanks, Jim
I obtained data from Supplier; however, in spite of my, what I thought, careful attention installed the unit backwards, easily done. Set throttle in reverse to go forward & vice versa. Dangerous situation.
Eventually had a contractor install properly.
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Old 14-07-2015, 13:33   #14
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Re: Proper Prop pitch for Maxprop

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I obtained data from Supplier; however, in spite of my, what I thought, careful attention installed the unit backwards, easily done.
Easily done but easily checked for as well. The curved blade edges should be facing aft when the prop is feathered fore and aft.

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Old 14-07-2015, 15:35   #15
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Re: Proper Prop pitch for Maxprop

Just remember, changing the Max-prop pitch under water is not easy. Few divers can do it, and you can't check it. Another option is a short haul for the change. Neither is cheap, so getting it right the first time is highly desirable.
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