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 Post subject: best propeller pitch
PostPosted: 16 Sep 2012, 17:35 

Joined: 07 May 2012, 19:50
Posts: 9
i am thinking about buying a 15 hp evinrude motor but it needs a propeller
i want to get a 4 bladed propeller and was wondering what pitch to get they are 9.25x 7,8,9,10 or 11
Thank You


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 Post subject: best propeller pitch
PostPosted: 16 Sep 2012, 18:55 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
Far to little info to even begin to give advice. What year motor? What prop was on it? What are you putting it on? What is the purpose, trolling or main motor? What were the RPMs before and why do you want a 4 blade.....etc.

A 4 blade will give more lift to a boat and better holeshot but will take away from top end. Also they bite harder and have more drag than a 3 blade so always go down in pitch.But since you don't have any data from any prop you are just peeing into the wind and guessing.



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 Post subject: best propeller pitch
PostPosted: 17 Sep 2012, 00:34 

Joined: 28 May 2011, 15:06
Posts: 175
Put me down for the 3-blade 8 pitch. (middle of the road)


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 Post subject: best propeller pitch
PostPosted: 17 Sep 2012, 01:07 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
PATRIOT2 wrote:
Put me down for the 3-blade 8 pitch. (middle of the road)


Did you mean 4 blade 8 pitch? Stock props for a 15hp are usually 9.5X10 so in theory an 8 or 9 pitch 4 blade could be the right solution but once again we have no info to start from and it is merely guessing



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 19 Sep 2012, 14:00 

Joined: 28 May 2011, 15:06
Posts: 175
Johny25 wrote:
PATRIOT2 wrote:
Put me down for the 3-blade 8 pitch. (middle of the road)


Did you mean 4 blade 8 pitch? Stock props for a 15hp are usually 9.5X10 so in theory an 8 or 9 pitch 4 blade could be the right solution but once again we have no info to start from and it is merely guessing

Nope, I'm just going by the owners manual for my 15HP.


MY PROP CHART.JPG
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 Post subject: best propeller pitch
PostPosted: 19 Sep 2012, 14:03 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
Huh what year and brand motor is that for?



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 19 Sep 2012, 23:30 

Joined: 28 May 2011, 15:06
Posts: 175
1987 Nissan NS15


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 Post subject: best propeller pitch
PostPosted: 20 Sep 2012, 00:18 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
You have a 1.85:1 gear ratio. That is why you have to run such a low pitch prop. Johnson/Evinrude 15's have a 2.41:1 gear ratio and can turn a higher pitch prop.

With your gear ratio and RPM and range (4750-5500) you can turn an 8 pitch 3 blade at 5500rpm and hit 19mph with a 15% slip but if you stick that same 8 pitch on the J/E you will only get to 15mph at 5500rpm at 15% slip. See what I am saying, two completely different motors and setup needs. Fact is the J/E would turn that 8 pitch at way too high an RPM unless it is on a pontoon or a heavy boat. The J/E is rated for 5500-7000rpm. I am assuming he has a 70's, 80's or 90's Evinrude mind you.

His J/E most likely came with a 9.5X10 prop which is typical for these motors. Basically he has to turn a 10pitch at 5500 with his gearcase to get close to what you get with an 8 pitch



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 20 Sep 2012, 00:26 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
Usually the 7 and 8 pitch props for the J/E's are for when you use the motor as a kicker on a heavy boat for trolling. The 9 and maybe 10 pitch would be for a heavy tin boat (14-16') and the 11 pitch and up would be for light applications on 10-12' lightly loaded tins. Hell even a bare bones 14' tin would fly with a 11 pitch on a 15hp J/E.

This is not set in stone, just a generalization of what these different pitched props could be used for. To get real technical I need to know the motor year and brand, GPS readings of current prop, prop specs (pitch, number of blades and diameter), RPM readings from a reliable tachometer and boat setup/brand/model



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 20 Sep 2012, 18:50 
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Joined: 03 Jan 2011, 12:29
Posts: 902
Location: british columbia canada
9 1/4 x 11 j. i have a 2011 15 2 stroke yami.when i bought it i asked them what prop will be best,and they told me its on there now.didn't even try to upsell me.keep in mind a 15 hp is not exactly a monster in the power department.



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 Post subject: best propeller pitch
PostPosted: 20 Sep 2012, 19:53 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
YOU CANNOT RECOMMEND A PROP FOR SOMEONE WHEN YOU ARE TALKING ABOUT A COMPLETELY DIFFERENT MOTOR WITH A COMPLETELY DIFFERENT GEAR CASE!!!!!!

You have a 2.08:1 gear case on that Yamy and a totally different RPM range so your input about your motor has NO bearing on the OPs question.......I just got done explaining this 2 posts above. Your giving bad info to someone with a totally different engine



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 21 Sep 2012, 00:26 
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Joined: 15 May 2010, 00:38
Posts: 1266
Location: Central Florida
Johny25 wrote:
YOU CANNOT RECOMMEND A PROP FOR SOMEONE WHEN YOU ARE TALKING ABOUT A COMPLETELY DIFFERENT MOTOR WITH A COMPLETELY DIFFERENT GEAR CASE!!!!!!

You have a 2.08:1 gear case on that Yamy and a totally different RPM range so your input about your motor has NO bearing on the OPs question.......I just got done explaining this 2 posts above. Your giving bad info to someone with a totally different engine


You learn well, grasshopper!! Keep it up.


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 Post subject: best propeller pitch
PostPosted: 21 Sep 2012, 01:58 
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Joined: 14 Feb 2012, 22:46
Posts: 1117
Location: North Idaho
I am not sure if you are applauding my grouchy response or that my prop info was good :lol: Now that was funny right there :mrgreen:



_________________
BOATS:
2002 Lowe 1467t
1988 Bluefin Sportsman 1900
1989 Spectrum 1900

MOTORS:
69' 6 hp Evinrude
71' 6 hp Johnson
85' 90 hp Evinrude
87' 9.9 hp Johnson (modified to 15hp)
88' 25 hp Johnson (modified to 30hp)
93' 120 hp Johnson
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 Post subject: best propeller pitch
PostPosted: 21 Sep 2012, 20:44 

Joined: 24 Dec 2011, 22:06
Posts: 342
Location: 72032
For that matter, an accurate prop suggestion would almost impossible without knowing the boat, how much weight, how it's loaded, motor height, current pitch/dia/ and RPM-among other things.

Find a stock 3 blade, get a tach and go run around on the water. Then tell us what the RPM is and we can get pretty close.

Dad's 1432 J/E 15 runs a Solas Aluminum 9" 4 blade. 4 blade for getting it out of the hole quickly because sometimes it's loaded down pretty good.


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 Post subject: best propeller pitch
PostPosted: 21 Sep 2012, 20:55 
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Joined: 03 Jan 2011, 12:29
Posts: 902
Location: british columbia canada
Pappy wrote:
Johny25 wrote:
YOU CANNOT RECOMMEND A PROP FOR SOMEONE WHEN YOU ARE TALKING ABOUT A COMPLETELY DIFFERENT MOTOR WITH A COMPLETELY DIFFERENT GEAR CASE!!!!!!

You have a 2.08:1 gear case on that Yamy and a totally different RPM range so your input about your motor has NO bearing on the OPs question.......I just got done explaining this 2 posts above. Your giving bad info to someone with a totally different engine


You learn well, grasshopper!! Keep it up.

holy crap dude,lighten up



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