DearJon
Well-known member
Ok fellas,
This one has been debated for a long, long while, but I'm going to open another thread on it. I am not getting exactly the performance I want from my boat/motor with my current prop. Maybe someone on here can give me a few pointers. I had a 1994 Honda 35 hp four stroke on the back of my G3 1548. When it finally gave up the ghost, I repowered with a 2012 Yamaha F40. When I installed the new motor, it did not come with a prop. Much to my amazement, the old prop off the Honda fit perfectly. It was an old aluminum Michigan Wheel 10.75" dia X 13" P that was pretty worn and had lots of dings in it. I suspect it might have measured 11" in diameter when it was new. I went out and did all the break in with this prop. After break in, my top speed was 32 mph at about 5800 RPMs. Sounds pretty good, right? Well, I thought that if I bought a new prop, it might do even better. So, I purchased a Solas aluminum 11" dia X 14" P prop. I figured if the old beat up 13 pitch prop was spinning at 5800, I could stand to lose 200 RPMs by going to the new 14 pitch prop. If my motor could still spin this new 14 P prop at 5600 RPMs, then I expected to gain 1-2 mph. Well, nothing could be further from the truth. When I installed the new 14 P prop and test ran it, it performed terribly. I couldn't get my RPMs above 4500. Top speed was 23 mph. So much for only losing 200 RPMs per inch of pitch increase. I purchased another Solas aluminum prop that measured 11" dia X 13" P. I figured that this prop would most closely replicate the performance of my old, beat up michigan prop, but without all the dents and dings. When I installed this prop and test ran it, then numbers were better, but not awesome. Max RPMs were around 5400 and top speed was 29 mph. I finally decided to bite the bullet and get a SS prop. I thought the thinner blades would net me a few RPMs, and maybe a few mph too. I bought a Solas SS in 11" dia X 13" P, the same size as my aluminum one. Well, I just ran it today and I was disappointed again. Max RPMs was 5100 and top speed was 30 mph. I can't explain why the RPMs were lower, but they were. I just ordered another SS prop that measures 11.75" dia X 11" P. Hopefully, it won't send my RPMs over 6000. If it does, then I'll have to order a 11.75" dia X 12" P. This is getting expensive! BTW, I guess I have a few props for sale and they are all in mint condition, save the old Michigan. BTW, I ran the motor today without the throttle linkage connected. I used my finger to accelerate, because I wanted to make sure that the throttle linkage didn't need adjusting. Throttle linkage/remote cables are working fine and are adjusted properly. Any ideas why I got such a wide range of results?
Boat: 2003 G3 1548 (weight unknown, but it's pretty heavy. I've got 10 gallons of fuel and three batteries on board. Me and my wife weigh 350 combined. Trolling motor, Yeti cooler, side console etc.)
Motor: 2012 Yamaha F40 (Runs flawlessly as should be expected from a new motor)
Manufacturer recommended RPM range: 5000-6000
*All speed tests were done down and back, with the current and against the current and then averaged to get the most accurate reading from the GPS. I even double checked my Lowrance with a hand held to make sure.
This one has been debated for a long, long while, but I'm going to open another thread on it. I am not getting exactly the performance I want from my boat/motor with my current prop. Maybe someone on here can give me a few pointers. I had a 1994 Honda 35 hp four stroke on the back of my G3 1548. When it finally gave up the ghost, I repowered with a 2012 Yamaha F40. When I installed the new motor, it did not come with a prop. Much to my amazement, the old prop off the Honda fit perfectly. It was an old aluminum Michigan Wheel 10.75" dia X 13" P that was pretty worn and had lots of dings in it. I suspect it might have measured 11" in diameter when it was new. I went out and did all the break in with this prop. After break in, my top speed was 32 mph at about 5800 RPMs. Sounds pretty good, right? Well, I thought that if I bought a new prop, it might do even better. So, I purchased a Solas aluminum 11" dia X 14" P prop. I figured if the old beat up 13 pitch prop was spinning at 5800, I could stand to lose 200 RPMs by going to the new 14 pitch prop. If my motor could still spin this new 14 P prop at 5600 RPMs, then I expected to gain 1-2 mph. Well, nothing could be further from the truth. When I installed the new 14 P prop and test ran it, it performed terribly. I couldn't get my RPMs above 4500. Top speed was 23 mph. So much for only losing 200 RPMs per inch of pitch increase. I purchased another Solas aluminum prop that measured 11" dia X 13" P. I figured that this prop would most closely replicate the performance of my old, beat up michigan prop, but without all the dents and dings. When I installed this prop and test ran it, then numbers were better, but not awesome. Max RPMs were around 5400 and top speed was 29 mph. I finally decided to bite the bullet and get a SS prop. I thought the thinner blades would net me a few RPMs, and maybe a few mph too. I bought a Solas SS in 11" dia X 13" P, the same size as my aluminum one. Well, I just ran it today and I was disappointed again. Max RPMs was 5100 and top speed was 30 mph. I can't explain why the RPMs were lower, but they were. I just ordered another SS prop that measures 11.75" dia X 11" P. Hopefully, it won't send my RPMs over 6000. If it does, then I'll have to order a 11.75" dia X 12" P. This is getting expensive! BTW, I guess I have a few props for sale and they are all in mint condition, save the old Michigan. BTW, I ran the motor today without the throttle linkage connected. I used my finger to accelerate, because I wanted to make sure that the throttle linkage didn't need adjusting. Throttle linkage/remote cables are working fine and are adjusted properly. Any ideas why I got such a wide range of results?
Boat: 2003 G3 1548 (weight unknown, but it's pretty heavy. I've got 10 gallons of fuel and three batteries on board. Me and my wife weigh 350 combined. Trolling motor, Yeti cooler, side console etc.)
Motor: 2012 Yamaha F40 (Runs flawlessly as should be expected from a new motor)
Manufacturer recommended RPM range: 5000-6000
*All speed tests were done down and back, with the current and against the current and then averaged to get the most accurate reading from the GPS. I even double checked my Lowrance with a hand held to make sure.