which prop for better performance and wot

[lime4x4]

I have a 1986 searay 268 weekender. The boat when fully loaded and on the water is real close to 9000 lbs.After having numerous engine issues over the last 2 years i pulled the old engine and installed a 350 vortec engine. Performance is way better but still have room for improvement. Current prop is a mercury mirage 3 blade ss 15.75X15 pitch can hit 4100 rpms.I should be at around 4600 rpm's at wot.

 

[junior1113]

Re: which prop for better performance and wot

4 blade 13pitch would work good and increase rpms about 150 or a 13 3blade would bring it up about 300. four blades have more torque another blade pushing water is alwways better with a big load

 

[hwsiii]

Re: which prop for better performance and wot

Lime, this is the information I have on your boat listed below with my best guesses for weight, the base weight should be right, look in your boat for the tag that shows base weight. What I don't have is the HP, Gear Ratio and deadrise in the hull, if you will give me this information I will run an analysis to see which prop you need.

Boat and Motor Info

H

 

[lime4x4]

Re: which prop for better performance and wot

300 hp 21 deg deadrise and a 1.5 gear ratio

 

[hwsiii]

Re: which prop for better performance and wot

Will you give me the speed at 4,100 RPm so I can figure out your Prop Slip. I would also like to know the RPM and MPH with this same prop and the old motor.

H

 

[lime4x4]

Re: which prop for better performance and wot

31 mph according to gps

 

[TilliamWe]

Re: which prop for better performance and wot

My dad had an 87 268 with the 330hp 454Magnum. And he used a 15pitch prop. So you would need less pitch than that.