Jackplate question

[dbw1968]

I have a 98 Ranger 518 DVS. My 150 optimax blew so I just bought a 20 175 Pro XS. I also added a 6 in jack plate. Guys that installed said it was all set. I took it out and runs great but I could only get 5400 RPMs and a speed of 54. My 98 150 did this. I measured where they set they JP and it was 4.75 from pad to center prop. That seems way too low. I got out of the hole quick but no top speed even trimmed up as high as I could. Was u stable trimmed up. I could only hit 4900 RPMs at WOT trimmed all the way down. Also running a 4 blade 21P offshore prop which was perfect for my older motor. Any suggestions where to set all this. This motor should push mid 60's.

[jimsch]

Seems way too deep but I would start by raising it about 1/2" and see what it does. Keep an eye on water pressure, if good, raise 1/4" at a time until you get the RPM's up or see the water pressure drop.
I run my 2014 518/200 Pro XS at 3".

[dbw1968]

What water pressure am I looking for? 20psi? It's my 1st jack plate. Is 1/4 in 1 full turn?

[mdtritn21]

If you are sure it's at 4.75 raise it to 3.5 and test it there 4.75 is way too low. Your probably going to have to buy another prop but test it with what you have on it for now. Keep your water pressure over 15 Lbs. at WOT.

[dbw1968]

I raised it to 3.75. Gained 100 RPMs, water pressure still 25. I'm gonna raise it again

[dbw1968]

Update. I finally got my throttle at 100%. Went and ran it. RPMs at WOT are 5900 and 58.3 MPH with my 4 blade 21p. My water pressure is still over 20. Should I continue to raise until my pressure starts dropping? P2P is still at 3". Then if my RPMs hit rev limit I can try my 3 blade Tempest 22p. I usually gain a few RPMs with the 22p 3 blade over my 4 blade. I then can start pitching up from there until I hit the sweet spot. You guys have really taught me a bunch and I appreciate everything.

[KYRANGERMAN]

I would definitely look at going up in prop pitch. I had a 96 Javelin 379 DC with an Evinrude Intruder 150 and a Slidemaster 6" jack plate and I was running a 24p Raker 3 blade prop. When I moved to my 2000 Ranger R83 with an Evinrude Ficht 150 and the same jack plate I went, at the dealers suggestion, a 25p Renegade 4 blade prop. I've never moved the jack plate since I bought the boat 20 years ago and I've always run at about 5700 RPM and somewhere in the mid 50's as far as speed.

It sounds to me as you are under propped as far as pitch. See if any of your buddies has a 23 - 25 pitch prop you can try. My feeling is that you can get the RPM's down and the top speed will stay the same or maybe go up a bit.

[dbw1968]

I would definitely look at going up in prop pitch. I had a 96 Javelin 379 DC with an Evinrude Intruder 150 and a Slidemaster 6" jack plate and I was running a 24p Raker 3 blade prop. When I moved to my 2000 Ranger R83 with an Evinrude Ficht 150 and the same jack plate I went, at the dealers suggestion, a 25p Renegade 4 blade prop. I've never moved the jack plate since I bought the boat 20 years ago and I've always run at about 5700 RPM and somewhere in the mid 50's as far as speed.

It sounds to me as you are under propped as far as pitch. See if any of your buddies has a 23 - 25 pitch prop you can try. My feeling is that you can get the RPM's down and the top speed will stay the same or maybe go up a bit.

I have a Tempest plus 23p I can try. Gonna give that a shot.

[Dubee]

I would definitely look at going up in prop pitch. I had a 96 Javelin 379 DC with an Evinrude Intruder 150 and a Slidemaster 6" jack plate and I was running a 24p Raker 3 blade prop. When I moved to my 2000 Ranger R83 with an Evinrude Ficht 150 and the same jack plate I went, at the dealers suggestion, a 25p Renegade 4 blade prop. I've never moved the jack plate since I bought the boat 20 years ago and I've always run at about 5700 RPM and somewhere in the mid 50's as far as speed.

It sounds to me as you are under propped as far as pitch. See if any of your buddies has a 23 - 25 pitch prop you can try. My feeling is that you can get the RPM's down and the top speed will stay the same or maybe go up a bit.

If he isn't hitting the limiter he doesn't need his rpm's to go down

[dbw1968]

If he isn't hitting the limiter he doesn't need his rpm's to go down

I agree. I'm gonna raise my JP 1/4" and get my RPMs up. Then try the props. I replaced all of my fuel Lines. My motor was starving for fuel pretty bad. This alone may give some more RPMs. I'll give her a test this weekend.

[KYRANGERMAN]

If he isn't hitting the limiter he doesn't need his rpm's to go down

If it was me and I could get the same speed but at a lower RPM then I would definitely go up in prop pitch. My theory is that I'm putting less stress on the engine to get the same result. But that's just the way I look at it.

[Dubee]

If it was me and I could get the same speed but at a lower RPM then I would definitely go up in prop pitch. My theory is that I'm putting less stress on the engine to get the same result. But that's just the way I look at it.

But that's not how it works. You want it propped so you reach the redline at full throttle. If your motor is designed to turn 6k and you prop it to turn 5500. You are actually putt more stress on it

[dbw1968]

But that's not how it works. You want it propped so you reach the redline at full throttle. If your motor is designed to turn 6k and you prop it to turn 5500. You are actually putt more stress on it

Exactly. Better for the motor and more efficient if u get full RPM capability at WOT.

[dbw1968]

Update. Replaced all of my fuel Lines. Purrs like a kitten now. I tried a Tempest plus 23p. I was at 5500 RPMs at 61MPH. Water pressure was 24. Raised UP 1/4" and I was at 5630 RPMs at 62 MPH. Water pressure still at 24. I put my 4 blade just to see and I was at 6010 RPMs and 59.3 MPH. Do y'all agree with me keep raising 1/4" at a time and stay with the 23p until I lose speed or water pressure drops and then lower a bit after that. If my RPMs don't go up enough I'll try my 22p again.

[mdtritn21]

What shape is the 23" prop in, is it new or used and how many hours do you have on the motor? You can keep raising until you gain rpm's but not speed, lose water pressure or lift. As far as rpm's that motor is designed to have max hp at or near top rpm's but you may not make it there on that boat. I don't think it will run very well above 3" under. I hope your trying all this loaded not running light.

[dbw1968]

What shape is the 23" prop in, is it new or used and how many hours do you have on the motor? You can keep raising until you gain rpm's but not speed, lose water pressure or lift. As far as rpm's that motor is designed to have max hp at or near top rpm's but you may not make it there on that boat. I don't think it will run very well above 3" under. I hope your trying all this loaded not running light.

I have 9 hours on the motor. 1 hour left to break in. I can hit WOT for 5 minutes at a time. I ride around at cruising speed, then open her up for Maybe a minute at a time. Boat is pretty much loaded minus rods and some tackle. 20 gallons of gas, live wells full, 4 batteries, ultrex, and graphs. I am running it by myself though, so I am missing some weight for sure. I'm using my sons 23p. It's in good shape though. I tried a 22p from the prop place that was in great shape and I gained RPMs over my 4 blade a couple of weeks ago. With me hitting over 6000 with my 4 blade I didn't want to try it again in fear of hitting rev limit only having 9 hrs. I'm at 2 3/4" p2p right now. I'm getting closer to optimal setup every move I make. Don't Think I'm gonna get much more speed, but I'm happy with 60mph in that heavy boat. If i can get RPMs up with the 23p, I think I may hit around 65. Watcha think?

[lpugh]

^^^^^ that is you best information on this page
Use the height to adjust for the best speed and handling, while making sure the water pressure does not go below 16 psi, do not use height to change rpm as that is done with the correct prop

[dbw1968]

^^^^^ that is you best information on this page
Use the height to adjust for the best speed and handling, while making sure the water pressure does not go below 16 psi, do not use height to change rpm as that is done with the correct prop

So what prop should I use on to get my best speed and handling? I have my 4 blade on it now, and my speed keeps going up and handles well. I was just worried about my RPMs getting too high before I reached max speed with this prop. Am I wrong to switch to 3 blade 23p during this step? I figured if I max speed out on this one and my RPMs are under max I can down pitch to gain my desired RPMs?

[mdtritn21]

Just keep using the 23 tempest to break it in and once you can run it WOT all the time then put the rider in with you and see how bad it drops off. You may end up with the 22 tempest on it.

[dbw1968]

That's what I'm Thinking too. 22p may be perfect.