Repower prop selection

[Ling king]

I know that there is another thread regarding props. I just didn't want to interfere with original thread.

I have a 2001 282 Sailfish that has twin Yamaha 200 2 stroke with a 4 blade props (OFS4R14PCL200) 15 1/4" diameter x 14 pitch. I replaced the original 3 blade props awhile back because the props were original with the boat and needed an upgrade. You can tell they were tuned a number of times and had a couple of dings when I first got the boat.

With the new 4 blade props I definitely got some serious torque and it planes in seconds. Top RPM's was about 4800. I did lose about 10 MPH top speed and about 1/2 a mile per gallon of fuel efficiency. Which adds up when your talking range.

Now I'm going to repower with Yamaha 4.2L 250 4 strokes and planning on using the same props. I would think that with more power the RPM's will max out around 5500 and 50 mph max.

What do you think? Research tells me it's going to be a good combination. Engines are going on Feb 1, so within a couple of weeks after will be test time. I'll keep you guys posted.

 

[family affair]

Because I don't know your level of experience with prop selection, I could be stating the obvious. Are the gear ratios from the old to the new engines the same? Every engine has characteristics that can make it challenging to find the best performance out of props due to diameter, pitch, engine height on the transom, and gear ratios. 4 blades typically kill fuel economy and top end speeds unless you can raise them high enough by moving your engines up on the transom. Even then water flow off the back off the boat might not allow for this to work well if the water is more turbulent closer to the hull.
Can your plan work? Maybe, but there are a lot of variables that can affect the outcome that might still require trial of different props till you get it right. Ken at Prop God's is the go to guy for things like this. He might even know someone who has already done this. Good luck!

 

[Ky Grady]

I'm repowering also in the next few months, or whenever Yamaha decides to ship motors. I spoke with Ken initially when I bought my boat and I went to the PowerTech 4 blade OFS prop also. Been a great prop, definitely helped with hole shot and mid range grunt that the F225 lacks. Wanting to keep a 4 blade prop on the new 4.2 F250, I gave Ken a call again. He said that I should keep my current prop and I'd be fine with running it on the new motor, said I may loose a couple miles an hour on top end but the 4 blade performance that I'm use to will be there. I'm going to break the new motor in with the factory 3 blade then switch to the 4. Full throttle max is 6000, if you're turning 5500 I'd say you're good to go with your current props. I'd still reach out to Ken and see what his recommendations are for you. He's a great source of knowledge with props.

 

[Keitha]

a 14 pitch prop on those motors is like driving your SUV around in 2nd gear. No doubt you lost 10mph and are sucking gas. I'm really surprised that you are only getting 4,800rpm WOT however. I would imaging you would be overspinning the props and bouncing off your rev limiter.
Did you play around with the Prop selector on the Yamaha website? It actually does a good job of getting you into the ballpark of what you should be running.

 

[wrxhoon]

I know that there is another thread regarding props. I just didn't want to interfere with original thread.

I have a 2001 282 Sailfish that has twin Yamaha 200 2 stroke with a 4 blade props (OFS4R14PCL200) 15 1/4" diameter x 14 pitch. I replaced the original 3 blade props awhile back because the props were original with the boat and needed an upgrade. You can tell they were tuned a number of times and had a couple of dings when I first got the boat.

With the new 4 blade props I definitely got some serious torque and it planes in seconds. Top RPM's was about 4800. I did lose about 10 MPH top speed and about 1/2 a mile per gallon of fuel efficiency. Which adds up when your talking range.

Now I'm going to repower with Yamaha 4.2L 250 4 strokes and planning on using the same props. I would think that with more power the RPM's will max out around 5500 and 50 mph max.

What do you think? Research tells me it's going to be a good combination. Engines are going on Feb 1, so within a couple of weeks after will be test time. I'll keep you guys posted.

Are you sure your rev counters are correct?
Doing simple math ( assuming you have 1.86 gears) at 4400 your theoretical speed is about 31.5 mph, at 4800 34.4 mph . If you allow for some slip you will be going under 30 mph. Do you think that is about the speed you were doing? If that is so it means your engines are down on compression, unlikely if both are at the same RPM at WOT but possible.
Your boat with 14" props should rev well over 5000 rpm. What pitch were the 3 bladers you replaced?
If you retain your 14' props on the 250 's (1.75 gears) you will only do about 40mph, I would think you want a higher pitch prop , more like 17", that would go close to 50 mph.
Contact Grady and ask them what pitch props they recommend for your boat or a prop specialist that has propped Gradys.

 

[fishing-ed]

what props did you end up with and wich ones did you try I am finishing up a renovation and have f300xbs on pallet