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Old 24-05-2012, 08:37   #1
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Thumbs up 78 pearson 30 maximum allowable prop size

i have a sweet pearson 30 (78) and recently repowered with a yanmar 15. does anyone know the maximum prop i can use? a prop shop said a 15x9 would power it well if it fits. any halp? thanks!! i look forward to being part of this community!
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Old 24-05-2012, 08:52   #2
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Re: 78 pearson 30 maximum allowable prop size

All that matters in terms of "fit" is that the upper most tip of the prop has adequate clearance from the bottom when the prop is installed. If there is a prop on the boat now, measure that clearance and try to find out the size of the prop. That should tell you if the new prop will fit.

There is a ton of info on this great boat on the net.. I don't know if prop size is discussed anywhere, however.. Google "Spartina" to find a great site for upgrade info.
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Old 24-05-2012, 08:55   #3
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Re: 78 pearson 30 maximum allowable prop size

boat is on mooring, weather crappy. i guess their are no shortcuts in sailing...thought someone might have that info....thanks!!
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Old 24-05-2012, 09:03   #4
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Re: 78 pearson 30 maximum allowable prop size

Is the 15 x 9 a 2 blade prop? If you will be doing a lot of cruising, you might be better off with a 3 blade.. I think a 3 blade will have smaller diameter but more thrust, better backing, etc.
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Old 24-05-2012, 09:47   #5
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Re: 78 pearson 30 maximum allowable prop size

Yes, if you're changing props anyway, definitely go fo rthe 3 blade. Did an Atomic 4 come out of it? Maybe try the existing prop and see where you are at. The engine should reach with in a few hundred RPM of maximum wide open. I believe 15% of diameter is the clearance required between prop tip and the hull. For a 15" prop that's about 2.25 inches.
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Old 24-05-2012, 10:58   #6
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Re: 78 pearson 30 maximum allowable prop size

it had an english-made westerbeke single cylinder diesel that sounded like the african queen. the prop belongs on a beanie not a sailboat.
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Old 24-05-2012, 13:01   #7
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Re: 78 pearson 30 maximum allowable prop size

Quote:
Originally Posted by simplynick912 View Post
it had an english-made westerbeke single cylinder diesel that sounded like the african queen. the prop belongs on a beanie not a sailboat.
I hope you did not repower because you did not like the way the Westerbeke sounded.. Nothing wrong with a 1 cylinder for powering a P30, and the prop had to be small for that engine.
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Old 25-05-2012, 07:21   #8
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Re: 78 pearson 30 maximum allowable prop size

I took possession of vivace with a blown cylinder and bartered my carpentry skills for a rebuilt yanmar15 and gear box. The shaft and prop, however remained. I have long held the view that if it's not broke don't fix it. That said I am still interested in learning what is the largest prop size she will take. Thanks for your input!
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Old 26-02-2013, 17:11   #9
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Re: 78 pearson 30 maximum allowable prop size

I have a 1974 pearson 30, repowered with an 18hp volvo diesel. (was A4 originally)

I have on it a 14x12 2 blade. There is maybe an inch of clearance from the hull, certainly less than optimal.

IMHO, the prop doesn't give enough thrust. The engine is never under stress, and I must rev high to get any speed. I don't like revving over 2000 (noise, vibration, wear, etc), so I end up going less than 5knots most of the time, and less if there is a headwind.

I'd like to get a bigger prop, but there's no space for more diameter. I'm considering going 3 blade. Any suggestions?
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