best propeller pitch

TinBoats.net

Help Support TinBoats.net:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

boater55

Member
Joined
May 7, 2012
Messages
9
Reaction score
0
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
 
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.
 
PATRIOT2 said:
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
 
Johny25 said:
PATRIOT2 said:
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.
 

Attachments

  • MY PROP CHART.JPG
    MY PROP CHART.JPG
    74.6 KB · Views: 6,946
1987 Nissan NS15
 

Attachments

  • ManualCover1.JPG
    ManualCover1.JPG
    31.6 KB · Views: 6,933
  • ManualCover.JPG
    ManualCover.JPG
    47.3 KB · Views: 6,933
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
 
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
 
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.
 
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
 
Johny25 said:
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.
 
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:
 
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.
 
Pappy said:
Johny25 said:
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
 
bcbouy said:
Pappy said:
Johny25 said:
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

Really not a question of "lighten up" ......When someone offers information that really doesnt't have a clue what they are talking about it could cost the OP money if he takes that incorrect advice. The only similarity between the two 15hp engines is the numbers on the cowling.
 
I fish a lot of bedrock, ledges and shoals, so that was something else I figured into MY equation. I need to get the assend up in a hurry sometimes, so a lower pitch was my preference. I don't need WAO on my boat.
 
the motor is a 1976 evinrude it will be the main motor on my 12 ft v hull boat i am looking for the propeller that will deliver the most speed the motor does not have a propeller on it and i don't know what it had on it i only wanted a 4 bladed propeller because i assumed id would increase the speed
 
A 4 blade will not increase speed, it will take away from top end. Since it is a 76' model and does have the 2.41:1 gear case and RPM range 5500-7000k I would recommend a 3 blade 10 pitch prop if your putting it on a 12' tin. This would probably be a safe starting point to get some info. From there you can adjust in pitch to get optimum performance. But you have to start somewhere and cannot expect to get the perfect prop on the first try with out any data to go by. All we can do is give you an educated guess from our experiences.

If you can turn a 10pitch at 6250-6500rpm you should see numbers around 20-22mph assuming a 15%-18% slip
 

Latest posts

Top