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Posts: 176
| So I love my new motor, I have my 10 hours break in period done;
I'm getting 400% better gas mileage, quieter-much quieter, no smoke, trolling feature is awesome, but....
It's a 4 bladed 19 pitch stainless, it jumps on plane instantly without exaggeration, It tops out at 40mph at 5400 rpm's. That is the top rpm I get. I'm going to raise it up a hole, but other suggestions are welcome. Don't get me wrong, I love how it's working but I think I should be around 6000 for top rpm's.
Any suggestions?
Kevin
Edited by Nomadmusky 5/30/2019 9:55 PM
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
I would say you could potentially move it up 2 holes, then drop down in pitch to a 17. The move up 2 holes will get you roughly 200 rpms, then the drop in pitch by 2 inches will get you another 400 RPMs given you are getting the same prop brand and model.
Just curious...are you running a steel prop or aluminum?
Your motor is right on the cusp of seeing nice improvements going steel. Steel will flex less, the blades are thinner and are able to be cast into more aggressive designs. Also, you could also try a good 3 blade that has decent trailing edge cupping (michigan ballistic would be a decent example) to help lift the stern and keep your pitch a little higher as well.
Lots of possible options and if you post your numbers as you try things, it could be very interesting to see what results you come out with.
Steve |
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Posts: 176
| Steve,
Thanks for your input. I have a 4 blade stainless steel prop. I moved it up two holes last night, but didn't get to run it yet. I started looking at 17's last night. I am heading out today for a weekend trip, which will get me some time on the water. If the 17 would get me 400 and the two holes get me 200 that would put me right in the sweet spot of 6000 rpm's.
I will let you know my numbers this weekend.
Kevin
Edited by Nomadmusky 5/24/2019 11:14 PM
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Posts: 176
| Here are my weekend numbers: So it was at 5400 rpm's with a 40.0 top speed. I raised it two holes and now I'm getting 5700 and 41.7, it did touch 5800 on a long stretch, tailing wind, with a slight set of chop, but it was a "blip".
Hole shot was just as instantaneous.
I'm happy where it is at, but...It seems wise to get full performance since I have the motor. |
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Posts: 44
| If more speed is what you are after, you most likely need to go to a 3 bladed polished stainless prop. A good prop guy can take your numbers along with the make and model prop you are currently running and get you dialed in on the correct 3 blade. |
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Posts: 176
| I'm not sure that more speed is actually what I'm after as much as peek efficiency. I would assume that is met by having a prop that allows my rpm's to get into the sweet spot of approx. 6000 rpms. Maybe I'm wrong in my thinking.
Edited by Nomadmusky 5/31/2019 8:45 AM
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
I don't think you are wrong in your thinking at all. Much of what somebody desires out of their rig is really dependent on how they plan to use the rig. Some people are out for the flat out max speed, while others prefer to have a boat that handles really well in rough conditions. Other people might want their rig to work as a family fish/ski as well.
It all comes down to how you want your rig to perform for you.
Efficiency-wise, you can reach a maximum efficiency with a 4 blade, or a 3 blade. There will be differences in that efficiency, though. With a 4 blade, efficiency comes with handling and mid-range cruising speed. In rougher conditions, the 4 blade will stay hooked up better as there is more blade surface area in contact with the water. Given the rig is not over propped, it will most often result in better fuel mileage at midrange, have wonderful accelleration...but the sacrifice is top speed.
With a 3 blade, efficiency is better at the top end because the boat may be faster for the same RPM as the 4 blade. Handling will go down a touch because of the reduced surface area, and in most cases, an increase in prop slip. Holeshot and midrange might be a bit different as it most likely will take more rpm to keep the boat on plane as compared to the 4 blade.
All in all, setting up a boat with the best prop possible is literally a compromise between handling and speed. Find the balance that suits your needs the best and you will have a rig that performs efficiently in the way you want it to perform.
At this point, if you reached that 5700 with just you in the boat, your gear, and a full tank of gas, the only way to make it reach that 6000 now is to repitch... I'd go 1 inch in pitch up if you can, (either have the prop re-pitched or buy a different one, keeping the current as a spare). Then, when you get another body in the boat, you will still have the ability to get the boat out of the hole and have solid midrange cruising speed.
Steve |
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Posts: 176
| @VMS Thanks for your recap. I was able to duplicate the 5700 with another fisherman with me and I didn't lose any performance. I agree with you. I think I will keep what I have and opportunistically find another 4 blade stainless as you recommend one inch in pitch up. (by the way which way is up)? If I'm at 18 now does that mean go to 17 or 19, sorry for what may seam like a silly question.
Kevin
Edited by Nomadmusky 5/31/2019 8:47 PM
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Posts: 386
| My advice is to save your $ and get a 17p aluminum. You're not going to see appreciable gains with ss on a 90. I run a 15p on my Warrior 1890 which weighs 1700 lbs empty and can run 6,000 RPM'S and I max out around 36mph. With a 17p I turn 5800 and can get 38mph
Edited by Pat Hoolihan 6/1/2019 5:41 AM
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
If you are at 18 pitch, up would be 19 as the pitch value stands for the theoretical number of inches the prop would move foreward in one revolution of the propeller.
Steve |
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Posts: 176
| @VMS
Steve,
Thanks, I would have went the other way.
I appreciate it.
Kevin |
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