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Prop size for Mariner 40hp

jsoriano

New member
"I bought a 15 foot Zodiac kin

"I bought a 15 foot Zodiac kind with a Mariner 40 HP, 4 cyl, short shaft, auto oil mix, elec star. It didnt came with the manual. I cant get it to speed even with 3 people. It has a 16´ prop, a mechanic told me that it is to big for this motor. Anyone knows what prop size and pitch are good for these motor.
Thanks."
 
"hi ive got a mariner 40 long

"hi ive got a mariner 40 long shaft, i can tell u but i keep the boat and engine over my dads ive recently changed the prop for a lover pitch wich gives me faster exceloration but a slightly lower top speed ill take a look tomorrow and send u the size and pitch on both props, hope this helps"
 
"Hi Javier,I put the info you

"Hi Javier,I put the info you posted,guessed a little and got 10-3/4x12 or 10-1/2x14.Post a little more info on weight and rpms. Even at that these calculators aren't always accurate."
 
"Thanks. It weight around 300

"Thanks. It weight around 300 pounds with out the motor, I have no idea whats the motors weight, my guess is 170 pounds. Do these motors say somewhere the range of prop that they can use?"
 
props are like tires on a car

props are like tires on a car and depending on your load some will work and other wont but what is important is knowing what you wave on it now other wise ......
 
"Javier, Cliff is absolutely c

"Javier, Cliff is absolutely correct. The "range" of pitches (and diameters) that you could potentially run on that motor is only limited by what various prop mfgs produce.

Noel notes two of the "more common" pitches (12 and 14) that you would see on that horsepower, but correctly matching a prop to a particular rig is not something you can find on a chart.

Even two identical boats, with identical motors could run significantly different props.

Depending on how the boat is used and what it's normal "displacement" weight is, will dictate which prop to run.

Additionally, the time of year and the altitude at which the boat is operated also effect what prop should be used.

Just as an example, I have a 14' Aluminum Princecraft with a full console powered by 15 horse Merc/Mariner with a 2.5 horse (twin)Evinrude kicker.

So boat weight is 225 pounds dry, plus 110 pounds worth of motors, plus 60 pounds of battery, plus 50 pounds of fuel (average) and maybe 15 pounds of safety gear (anchor, spare prop, fenders etc) - then add me and the wife (about 300 pounds - we are both skinny
) and the displacement weight is between 750-800 pounds.

In the spring and the fall, when the air is cooler and humidity is low I run a 4 blade, 10 pitch prop.

In mid summer when temp/humidity is high I swap out for a 3 blade, 9 pitch.

And if the boat is further loaded up near it's max displacement (or anywhere above about 1000 pounds - so an extra person with gear/junk for the day) I will swap out the prop for a 3 blade 7 pitch.

So one boat/motor combo = 3 different props, and actually it would still take one or two more to really cover all the ways I use the boat.

You can't get that information from a chart AND my example demonstrates that there is no "one size fits all" prop for your boat in every situation.

Every boat owner should sit down with a dealer "well versed" in props and determine what is best to fit the needs of their individual boat/motor combination...."
 
"sorry i havent got back soone

"sorry i havent got back sooner javier, but im snowed in , and unable to get to my dads , as soon as weather permits ill check prop sizes, but saying that the tremendous guys on this site have got it covered,all the best mr thomas"
 
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