i am looking to buy a stainless prop for my 2007 tidewater cc 19’ i need some information on what pitch would you suggest for this. i have a 2006 115 4strk yamaha. with the aluminum prop now it is running a little over six thousand rpms at approx 35mph. i am thinking that is over revving the engine. any thoughts or help would be appreciated. thanks
Some shops have test props. Try different pitches. The experts can correct me if I’m wrong but if your motor revving to high, you’d want to try a prop with a smaller pitch. You basically want to pick one that can bring your motor to max rpm without exceeding it. My yammer max is 6000. My prop, at full throttle, and boat trimmed up will rev to 6000. Over revving isn’t a great idea. Different pitches can change your max and provide different performance gains and losses. Relative to what you’re after.
Pursuit 2470 CC w/ Yam F250TXR
“Follow The Leader”
Pitch represents how many inches of travel will occur with one revolution of the prop. Example. A 15 pitch prop will propel the boat 15 inched with one revolution at zero slip. If you are running on the upper end of the RPM range with say a 15 pitch prop, moving to a 17 pitch will load the motor more and reduce the RPM’s. You may gain top end speed and loose hole shot. Going up in pitch lowers the max RPM’s, going down in pitch raises the max RPM’s at full throttle. Hope this is helpful. I have two props for my Yamaha F150, 17pitch and 18 pitch. I get a little more top end with 18 pitch, but 17 pitch has more hole shot and carries a load better.
What is the pitch and diameter of your current prop.
What Oneal said is correct.
He mentions the diameter of your prop.
You need to calculate the amount of “slip” you experiencing.
Generally speaking, larger diameter props slip less than props of the same pitch that are smaller in diameter, if the prop design is similar.
I have a brand new 17 pitch SS prop that runs slower at WOT than my current 15 pitch SS prop. Main difference is the diameter of the wheel.
Try to get as much efficiency first, that means calculating the amount of slip. You may need a larger diameter wheel. Shoot for the least amount of slip as possible, then move up and down in pitch to adjust the Max rpm.
I believe you can expect about 200 rpm change for each inch of pitch with similar design props.
218WA Sailfish
200 Verado
The "Penn"sion Plan
What Ari angler stated about test running some different props. I’ve had two identical props out of a box do slightly different. Get a few props if you are able and pick a warm day and a good know sandbar and do several test runs.
Ari angle got it wrong on the rpms though, more pitch equals higher top end if your engine can pull it and less rpms. lower pitch higher rpms quicker getting on plain but less top end.
I’ve done all the math when I used to own a few glitter boats and the numbers don’t always match up to real world application, close but not always on the money due to slippage, bow lift desired, etc.
Another option is to see John at skips prop shop and tell him what you are looking to do, he’s customized several props for me. might get him do just add a little cup to it.
IF ITS OVER 6000 RPMS, YOU ARE MOST LIKELY HITTING THE REV LIMITER.
YOU SHOULD BE 40 MPH OR MORE.
BASED ON YAMAHA PERFORMANCE BULLETINS FOR SIMILAR BOATS, A 17 PITCH STAINLESS PROP SHOULD PUSH THAT BOAT 40 MPH AT 5900-6000 RPMS.
www.teamcharlestonmarine.com
www.bombislandboats.com
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Thanks everybody for the tips. i am not that interested in going really fast; just want to get the right prop for the boat/motor. i am not sure what pitch is on it now. it is an aluminum prop. i need to find a good deal on a 17 pitch stainless for this 115 4strk yammy.
quote:
Originally posted by Fred67Ari angle got it wrong on the rpms though, more pitch equals higher top end if your engine can pull it and less rpms. lower pitch higher rpms quicker getting on plain but less top end.
As far as having it reversed with pitch, I apologies. To much going on at one moment. I did state that backwards. As far as RPM’s go, wouldn’t a higher pitch cause a reduction of peak RPM’s? So say I have a 17 @ 6000. If I went 15, I’d lose top end but motor would rev to 6200. (not accurate numbers, just example). If your over revving, going a step or two higher would help limit peak rpms.
Pursuit 2470 CC w/ Yam F250TXR
“Follow The Leader”
Before you do anything take it to Skips Prop Shop in North Charleston. He will tell you what the best course of action is.
Rebuild, repair, replace.
He should be able to tell you exactly what prop and pitch it is.
If you replace, recommend going with the exact same prop but in stainless steel.
Operating RPM for that motor is 5000-6000. I think your propped correctly it’s just old and lost it’s edge/cup and is slipping.
i am a little far away from n. charleston here in lexington but thanks for all of the info. i am going to find a 17 pitch stainless and give it a try.
CB, here is the performance bulletin for my Sportsman 20 Bay with 2017 115 Yam. They are real close with just me. You may have a little more deadrise and weight if yours is a traditional CC. If you want to try my prop, you can.
50
60
MPH
RPM MPH GPH MPG
1000 4.0 0.4 10.00
1500 5.8 0.8 7.25
2000 7.0 1.3 5.39
2500 10.0 1.9 5.26
3000 16.1 2.6 6.19
3500 22.0 2.9 7.59
4000 26.7 3.9 6.85
4500 31.0 5.0 6.20
5000 35.0 6.4 5.47
5500 38.3 7.8 4.91
6250 44.4 10.5 4.23
Sportsman® Island Bay 20
Length 20’ 1"
Beam 7’ 8"
Dry Weight (Boat Mfr. Pub) 1,500 lbs
Maximum HP 115
Fuel Capacity 34 gal
Weight as Tested 2,412 lbs
F115XB
Horsepower 115 HP
Induction EFI
Displacement 111.8 cu in
Weight 386 lbs
Gear Ratio 2.15:1
PROPELLER/S
Series Aluminum
Diameter/Pitch 13 x 19
Yamaha Part # 6E5-45941-00-00
Propeller Material Aluminum
TEST CONDITIONS
Number of People 2
Air / Water Temperature (Fahrenheit) 75 / 60º F
Elevation (in feet above sea level) 85’
Wind Velocity 0-5 mph
ENGINE MOUNTING HEIGHT
Mounting Hole Position #3
Ventilation Plate Height 1/2" Above Boat Bottom
Also, I know it’s an '06, but this may help.
http://www.yamahapropselector.com/propSelector/web/inner.html
I have a brand new 13.75" X 17P Stainless Yamaha prop that you can try if you want.
I bought it and ran it about 10 minutes. Too much slip for my boat but it may work for you.
PM me if you want to try it, I’m in Saluda.
218WA Sailfish
200 Verado
The "Penn"sion Plan