Not sure if this is the right place but have Another prop question here. I know enough to know I don’t know enough about props without seeking advice for my situation. I have called a couple of places and I even emailed Solas with no response from them. So first some info about the boat which is aluminum built for a 25 HP max lake near us. It is a 1982 Smoker Craft Big Fisherman that is 15’4” long, I think 72” wide and a 21” transom. It has a v bow that transitions to being flat at the stern. It came factory with a splash well, pedestal seats, bow storage, a live well(used for a soft sided cooler and storage) and a storage compartment on the port side with a rod locker on the starboard side. It had a side console and wood floor. The console and controls were removed to lighten and to make more room for fishing. The plywood transom core and rotted wood floor were replaced with Nida Core that was glassed and marine epoxied. The floor carpet and alum railing on the bow were removed to lighten it some more. There isn’t very much info on the net about the boat and Smoker Craft never replied to my inquiries about it. I believe the hull dry weight was about 540lbs but I don’t know what it is after being modified. A 12v Terrova trolling motor is on the bow now with a 27 group battery in the bow compartment. A 2018 Yamaha F25 tiller that is electric start with manual tilt hangs on the back. The starting battery and a 6 gallon gas tank tuck under the splash well. The transom is 21 degrees and the motor would only tilt 15 degrees so some wedges were added to tilt the motor out to provide more bow lift. The motor was raised up so the AV plate is about even or a little above the bottom of the boat. With the motor in the last pin out and while under plane the AV plate is above the water line. I’m guessing that the total weight of the boat as it’s ran is over 11-1200 pounds. The motor has a 5-6000 RPM operating range with a 6200 rev limiter.
Now the details for the three props I have that were tested the same day on a lake that was flat calm . I had 200 pounds of sand in the boat to simulate the wife and our dog. The motor came with a Yamaha 9 7/8” x 11 ¼ pitch prop. At wot it ran at about 5140 RPMs and 21.7 MPH. I tried a Solas Amita three 9.9” x 9 prop. It will hit the 6200 RPM rev limiter with throttle left over and tops out at about 20.8 MPH. Next was a Solas Amita three 9.9” x 10 prop. Top RPMs were about 5850 at about 22.7 MPH. I then took the sand bags out and with the 9.9” x 10 Solas prop I hit about 6040 RPMs and 24.8 MPH which is perfect when I’m by myself. All the props got up on plane good and I could turn as sharp as I dared with no blowout.
Now the issue. I’m trying to be as close as possible to 6000 RPMs at wot to be in the best power band of the motor. I seldom go out on the boat without the wife and dog. With them the Solas 9 is to small and always hits the rev limiter leaving a unknown amount of throttle left over. The 10 drops out of the best power band RPMs especialy when it’s windy and or we go up the head rivers against the current. There is at least 350 or probably like 500 or more RPMs difference between the Solas 9 and 10 pitch props. I need something that would be somewhere in between them. I have no prop shop near me. One place I called said I could ship them my Solas 9 pitch and they could add some ?cup? to it to lower the RPMs. I want to keep that prop in case I have a bigger load and need the smaller prop. Forgot to ask if they could get at least 200 more RPMs out of a Solas 10 pitch. The factory Yamaha 11 ¼ prop is too far off and is completely useless to me. I tried doing some kind of trade with it at my nearest dealer which is almost an hour away. Even though it’s still like new they wouldn’t do any kind of trade for a 10 ½ pitch. I wasn’t willing to pay the $150 + tax they wanted for the Yamaha 10 ½ pitch just to try it. Thinking I’m going to have to sell the 11 ¼ on *bay. Any thoughts/ advice from anyone with more prop experience on small horse power motors. What would be the best route to go? Have a Solas 10 reworked for more RPMs or get a 9 reworked to get less RPMs? Try the Yamaha 9 or 10 ½ or some other brand? From what I understand a four blade will lose me top end which I’d like to keep as much as possible so I feel a four blade is out. Don’t want stainless because of the cost and I’m always exploring skinny waters so afraid of hitting things. Thanks .
Now the details for the three props I have that were tested the same day on a lake that was flat calm . I had 200 pounds of sand in the boat to simulate the wife and our dog. The motor came with a Yamaha 9 7/8” x 11 ¼ pitch prop. At wot it ran at about 5140 RPMs and 21.7 MPH. I tried a Solas Amita three 9.9” x 9 prop. It will hit the 6200 RPM rev limiter with throttle left over and tops out at about 20.8 MPH. Next was a Solas Amita three 9.9” x 10 prop. Top RPMs were about 5850 at about 22.7 MPH. I then took the sand bags out and with the 9.9” x 10 Solas prop I hit about 6040 RPMs and 24.8 MPH which is perfect when I’m by myself. All the props got up on plane good and I could turn as sharp as I dared with no blowout.
Now the issue. I’m trying to be as close as possible to 6000 RPMs at wot to be in the best power band of the motor. I seldom go out on the boat without the wife and dog. With them the Solas 9 is to small and always hits the rev limiter leaving a unknown amount of throttle left over. The 10 drops out of the best power band RPMs especialy when it’s windy and or we go up the head rivers against the current. There is at least 350 or probably like 500 or more RPMs difference between the Solas 9 and 10 pitch props. I need something that would be somewhere in between them. I have no prop shop near me. One place I called said I could ship them my Solas 9 pitch and they could add some ?cup? to it to lower the RPMs. I want to keep that prop in case I have a bigger load and need the smaller prop. Forgot to ask if they could get at least 200 more RPMs out of a Solas 10 pitch. The factory Yamaha 11 ¼ prop is too far off and is completely useless to me. I tried doing some kind of trade with it at my nearest dealer which is almost an hour away. Even though it’s still like new they wouldn’t do any kind of trade for a 10 ½ pitch. I wasn’t willing to pay the $150 + tax they wanted for the Yamaha 10 ½ pitch just to try it. Thinking I’m going to have to sell the 11 ¼ on *bay. Any thoughts/ advice from anyone with more prop experience on small horse power motors. What would be the best route to go? Have a Solas 10 reworked for more RPMs or get a 9 reworked to get less RPMs? Try the Yamaha 9 or 10 ½ or some other brand? From what I understand a four blade will lose me top end which I’d like to keep as much as possible so I feel a four blade is out. Don’t want stainless because of the cost and I’m always exploring skinny waters so afraid of hitting things. Thanks .