Polebrother
Recruit
- Joined
- Apr 2, 2010
- Messages
- 1
I just put a 10 1/2 pitch prop on my Merc 60 hp four-stroke, replacing a 12-pitch prop to help get my 16ft Tracker Targa up on plane when the boat's passenger capacity is maxed out. As for performance, the new 10 1/2 pitch prop does exactly what I'd hoped it would do. I can now get up on plane with three people in the boat with RPM now reaching 6000. Previously, with the 12-pitch prop, RPM maxed out at 5200 with three people in the boat and the boat would never get up on plane, max speed 10 mph. I solved the problem but apparently created another one in the process.
My new prop makes a loud, squealing or whirring noise when RPM is between 1800 and 2000. When RPM is below 1800 or above 2000 the noise goes away. This poses a tremendous/unacceptable problem for me because I love to troll for stripers on the delta and more often than not I troll at speeds that put my RPM between 1800 and 2000, i.e., between 3.5 and 5 mph. Not only is the squealing noise distracting to me and other anglers in the boat, it cannot be appealing to the stripers I'm trying to entice. Also, when the prop squeals, my fish finder/sonar is rendered useless because the screen becomes totally cluttered with static/interference signals. When the squealing noise disappears, my fish-finder returns to normal with clean, crisp signals of what's below.
The rest of the story. This is the second 10 1/2 pitch prop I've had on the motor in the last two weeks. The first one made the same squealing noise the first time I trolled after installing it. I returned to the launch ramp early, recovered the boat to check the prop. Upon removing it I saw that 1/3 of the prop's circumference was scratched where it mates with the circular housing of the motor's lower unit, indicating it had been rubbing against the housing's wall. Scratch marks also appeared on the inner housing wall of the lower unit where it mates with the prop. I put the prop back on the motor and turned it slowly by hand and sure enough I could see where the prop was rubbing against the housing. It appeared that part of the prop was out-of-round. My immediate fix was to put the 12 pitch prop back on the motor so we could continue trolling. That's what I did and the 12-pitch prop made no noise whatsoever which allowed us to continue trolling effectively, even though we couldn't get up on plane to run between trolling spots. The dealer graciously replaced the defective prop without charge after observing the scratch marks and installed a new 10 1/2 pitch prop in my presence. We hand-checked the new prop and it spun quietly without making any contact with lower unit housing.
Back to where I am today. The new prop squeals like the first prop but there is no evidence of it rubbing against the housing. I took the new prop off after trolling yesterday and it looks perfect...no scratches, the painted black finish looks untouched, fully in tact without blemish.
Well, I said all that to say this...what's causing the squealing between 1800-2000 RPM and how can I fix it? Will appreciate any help offered. Thanks.
My new prop makes a loud, squealing or whirring noise when RPM is between 1800 and 2000. When RPM is below 1800 or above 2000 the noise goes away. This poses a tremendous/unacceptable problem for me because I love to troll for stripers on the delta and more often than not I troll at speeds that put my RPM between 1800 and 2000, i.e., between 3.5 and 5 mph. Not only is the squealing noise distracting to me and other anglers in the boat, it cannot be appealing to the stripers I'm trying to entice. Also, when the prop squeals, my fish finder/sonar is rendered useless because the screen becomes totally cluttered with static/interference signals. When the squealing noise disappears, my fish-finder returns to normal with clean, crisp signals of what's below.
The rest of the story. This is the second 10 1/2 pitch prop I've had on the motor in the last two weeks. The first one made the same squealing noise the first time I trolled after installing it. I returned to the launch ramp early, recovered the boat to check the prop. Upon removing it I saw that 1/3 of the prop's circumference was scratched where it mates with the circular housing of the motor's lower unit, indicating it had been rubbing against the housing's wall. Scratch marks also appeared on the inner housing wall of the lower unit where it mates with the prop. I put the prop back on the motor and turned it slowly by hand and sure enough I could see where the prop was rubbing against the housing. It appeared that part of the prop was out-of-round. My immediate fix was to put the 12 pitch prop back on the motor so we could continue trolling. That's what I did and the 12-pitch prop made no noise whatsoever which allowed us to continue trolling effectively, even though we couldn't get up on plane to run between trolling spots. The dealer graciously replaced the defective prop without charge after observing the scratch marks and installed a new 10 1/2 pitch prop in my presence. We hand-checked the new prop and it spun quietly without making any contact with lower unit housing.
Back to where I am today. The new prop squeals like the first prop but there is no evidence of it rubbing against the housing. I took the new prop off after trolling yesterday and it looks perfect...no scratches, the painted black finish looks untouched, fully in tact without blemish.
Well, I said all that to say this...what's causing the squealing between 1800-2000 RPM and how can I fix it? Will appreciate any help offered. Thanks.
