9x9 or9x10?

[7173george]

What would the performance diference be between these two props? i have a 14 foot mod. v jon boat. i run an old 1975 evinrude 25 hp motor.I always have myself and another person in the boat plus two batteries, baitwell and gear. i'm estimating total weight to be 1200 lbs.that includes boat, motor, gas, anchors, all of it. Right now it has a 9" dia.x10" pitch.What would a 9 x9 do? right now boat goes 21 mph on my gps.

 

[pootnic]

Re: 9x9 or9x10?

Should plane quicker,hard to tell what it will do to the top-end.
Maybe slower but could be the same or quicker depending on rpm.
Rpms are key when finding the right prop and life of a motor.

 

[steelespike]

Re: 9x9 or9x10?

Not knowing the rpm you can't really tell much.A 9" will definately have better hole shot
and will increase rpm.I do suspect that your slip is probably high; The 9" may imptove slip
numbers.The motor is rated for 5000 to 6000 rpm and at 1200 lbs a 9" isn't likely to exceed
that number. A Tinytach is reasonable and easy to install and will work on almost any motor
that has a spark. If the motor can make 5000 with the 9" it could manage speeds up to "about" 22.
If it makes 6000, not likely at 1200 lbs, with a normal slip number speeds could reach about 26.
A 25 on a light fast boat could reach "about" 32 at 6000 rpm with an 11" prop with 9% slip.

 

[damnskippy]

Re: 9x9 or9x10?

I have a 14' Starcraft V hull with a 1969 20 HP Johnson, it had a 9 1/4 x 11 prop, I switched up to a 10 pitch, added a homemade planing aid, between the two changes it made an incredible difference, for the better, I don't have any data to support my claims, but you could feel it "by the seat of your pants", guessing I picked up 8 or 10 mph, that is myself at 200 lbs, my buddy at 250lbs, all our gear, coolers, ect. Total weight around 900 lbs, and I would say the motor was not turning the max RPMs it was designed for, just my 2 cents, Skip