I own a 1979 Hunter 25ft using a 9.9 Mercury outboard for auxilliary power. I have no trouble attaining hull speed with this size outboard; however, even though the prop stays in the water, it does not have much push in a heavy seaway. The blade that I am using came with the boat/motor and I have no idea of its pitch, etc.; however, it does seem to have a lot of pitch. At the Detroit Boat Show (Jan 2001), I noticed that all the long shaft outboards shown (2 or 4 cycle) had relatively flat props (low pitch). Would appreciate knowing what type of prop should I be using (low or high pitch) and what the majority of you are using (low or high pitch).
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Ike Cook
Stamped
The diameter and pitch should be stamped on the prop in the respective order __x__. If you can find that out it'll be easier to lead you in a direction. Good Luck Ike
The diameter and pitch should be stamped on the prop in the respective order __x__. If you can find that out it'll be easier to lead you in a direction. Good Luck Ike
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Daniel H. Pitman
15 hp Force with a low pitch prop.
I use a low pitch prop. It moves the boat at hull speed and keeps the motor in it's proper power rpm range. 2 cycle engines have very little hp and torque at low rpms. Running the 2 cycle engine with a low pitch prop will stop the boat from exceeding hull speed while keeping the engine in it's designed rpm range for the hp it's rated. The other advantage of running a 2 cycle engine at a higher rpm is that it will keep the top of it's pistons clean, if the pistons carbon up the exhaust gases don't evacuate completely and the engine will lose power. Most smaller hp engines come with a high pitch prop because the majority of the time they are used to power a rowboat which is a light planing hull and needs to obtain and stay at a higher speed. The h25 is a displacement hull and will never be able to use all of a high pitch prop so for power and the engines sake it makes sense to use a low pitch prop. Hope this helps! Daniel H. Pitman s/v Essayons
I use a low pitch prop. It moves the boat at hull speed and keeps the motor in it's proper power rpm range. 2 cycle engines have very little hp and torque at low rpms. Running the 2 cycle engine with a low pitch prop will stop the boat from exceeding hull speed while keeping the engine in it's designed rpm range for the hp it's rated. The other advantage of running a 2 cycle engine at a higher rpm is that it will keep the top of it's pistons clean, if the pistons carbon up the exhaust gases don't evacuate completely and the engine will lose power. Most smaller hp engines come with a high pitch prop because the majority of the time they are used to power a rowboat which is a light planing hull and needs to obtain and stay at a higher speed. The h25 is a displacement hull and will never be able to use all of a high pitch prop so for power and the engines sake it makes sense to use a low pitch prop. Hope this helps! Daniel H. Pitman s/v Essayons
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Ray Bowles
Less prop size.
John, We have a 95 H26 with a Honda 9.9 hp outboard. This motor moved the boat at max speed while at very low RPM. We dropped 2 prop sizes and now it cruises nicely in mid RPM range which also raises the charge into the battery and runs the engine in the higher RPM range it was meant for. Any prop shop can help you. Your prop should have pitch numbers on it in mm,s. Good luck, Ray
John, We have a 95 H26 with a Honda 9.9 hp outboard. This motor moved the boat at max speed while at very low RPM. We dropped 2 prop sizes and now it cruises nicely in mid RPM range which also raises the charge into the battery and runs the engine in the higher RPM range it was meant for. Any prop shop can help you. Your prop should have pitch numbers on it in mm,s. Good luck, Ray
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Bernie
I have a 1999 Mercury 9.9 4-stroke Bigfoot Sailpower outboard. It needs a low pitch prop (usually called a "workboat" prop) so that you can be at the upper end of the recommended rpm range when at hull speed. If you are achieving hull speed at midway in the rpm range, your outboard is only able to provide about 1/2 its rated power or roughly 5 horsepower. Unfortunately, the Bigfoot model is fairly new, and Mercury has not yet provided a "workboat" prop (although I have heard that they will begin offering one later this year). My first attempt to resolve the problem was to replace my prop with a low pitch composite prop. Unfortunately, it was a slightly smaller diameter and that caused it to cavitate too much. What I currently have is the original prop that I had modified by a prop shop to lower the pitch by a couple of inches. The rpms are still not as high as they should be, but they are higher than they were before. I will likely order the workboat prop (with a pitch of around "6" whenever it is offered by Mercury.
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John Allison
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Steve
Michigan Wheel will solve you problem
Michigan Wheel makes many replacement props. I have a Johnson Saildrive, which had an OEM prop with a 9.5x8 configuration. I replaced with a Michigan Wheel 10x5 which gives much better performance with my Hunter 25. They have info on their website that will give you the details on the prop you need. (miwheel.com)
Michigan Wheel makes many replacement props. I have a Johnson Saildrive, which had an OEM prop with a 9.5x8 configuration. I replaced with a Michigan Wheel 10x5 which gives much better performance with my Hunter 25. They have info on their website that will give you the details on the prop you need. (miwheel.com)
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