208 with an F200. Currently running a 17 X 14 1/4. Can only get 5300 or 5400 rpm max. What prop would get me to the recommended 5800-6000 range and what would be given up?
Prop question
- Thread starter ric2352
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Has it always been this way since you've had the boat (how long?) and are you trimming up as far as possible? What type of load is on the boat when you've gotten that 5400? Is the boat hull VERY clean? Any damage to the prop?
engine and prop 3 years old. Hull perfect,trimmed correctly, load is usually 2 guys and fishing gear, no damage to prop. Thinking I didn't choose the optimum prop for this engineDennisG01 said:
If you drop down to a 15", you should gain about 300RPM, give or take. Maybe 400. That still doesn't get you to your upper limit and it's always better to be at (or even slightly higher as you control that with throttle) the upper limit for those times when you load up the boat even heavier. It could be the type/brand of prop you have, too. Another thought is that if it's a cheapie prop, then you have wonder how accurate the rating is. Take a look at Merc's sight - they have a prop picker tool. Also... although I've never personally needed to use him, I hear really good things about Ken at PropGods. If you have a decent shop near you, that would be another thought as they might work with you (loaners) to get the right prop.
Very generally speaking, what a lower pitch prop gives you is a better hole shot and the ability to raise your RPM towards the max of it's range (this is also good for the engine). A lower pitch prop equals slower top end speed for a given RPM, but because you will be gaining RPM, top end speed might be about the same. You will, however, decrease your cruising speed - in other words, for a given RPM - say 4,000 - the lower pitch prop will lower your speed. Meaning, to keep the same 25mph cruise speed (for example), your RPM's will be higher. That's the basics in a nutshell.
Very generally speaking, what a lower pitch prop gives you is a better hole shot and the ability to raise your RPM towards the max of it's range (this is also good for the engine). A lower pitch prop equals slower top end speed for a given RPM, but because you will be gaining RPM, top end speed might be about the same. You will, however, decrease your cruising speed - in other words, for a given RPM - say 4,000 - the lower pitch prop will lower your speed. Meaning, to keep the same 25mph cruise speed (for example), your RPM's will be higher. That's the basics in a nutshell.
Thank you......I have a Yamaha Reliance.....best I could get I think.....want to buy a cheap 15.25 X 15 to see the difference....what do u think?
I am. Running a 15p Reliance on my 208 no hard top with a Yam F200 i4. 2 on board with fishing gear etc, getting 43 mph at 5800 rpm WOT, Pacific Ocean Vancouver Island. Good luck, trapper 
Just double check that you have the clearance (anti-ventilation plate) for the larger diameter, but it sounds good.
What year hull?
I assume that the motor is a 6 cyl not the inline 4. Is that correct?
The factory WOT spec for F200 is 5000 to 6000. So you are not really off. What is more important is what revs you typically operate at and how the performance is in those conditions. As DennisG mentioned, you can compare several props all with the same spec and get quite different performance characteristics.
Personally, I rarely run at WOT on my 208. Once in a while I will open it up to max but just for a short amount of time just to blow things out and 'scrub' the hull.
I assume that the motor is a 6 cyl not the inline 4. Is that correct?
The factory WOT spec for F200 is 5000 to 6000. So you are not really off. What is more important is what revs you typically operate at and how the performance is in those conditions. As DennisG mentioned, you can compare several props all with the same spec and get quite different performance characteristics.
Personally, I rarely run at WOT on my 208. Once in a while I will open it up to max but just for a short amount of time just to blow things out and 'scrub' the hull.
Hull is a 95, with a hardtop, F200 4 cyl. 4 stroke. O n the west coast we can almost never run wot due to water conditions......25 mph is typical cruise speed. Think I'm tacking around 4000 to 4200 now at that sp eed.seasick said:
What's the diameter of your prop?trapper said:I am. Running a 15p Reliance on my 208 no hard top with a Yam F200 i4. 2 on board with fishing gear etc, getting 43 mph at 5800 rpm WOT, Pacific Ocean Vancouver Island. Good luck, trapper
You are overpropped.
Puts a heavier load on the engine throughout the entire operating range.
General rule of thumb is 300-400 RPM change for 2" pitch change. But that assumes same prop, i.e., no other variables changed.
Get the same prop in 15" PITCH and enjoy.
Puts a heavier load on the engine throughout the entire operating range.
General rule of thumb is 300-400 RPM change for 2" pitch change. But that assumes same prop, i.e., no other variables changed.
Get the same prop in 15" PITCH and enjoy.
From my experience, it is more like 200 rpms on a pitch change, especially with the reliance prop. You should not consider a 15 inch or larger dia. Prop on the f200 i4 Stay with the 141/4 dia.. trapper
I ran the Mercury prop calculator app using the following data:
Pitch 17in
gear ration 1.86 (Yamaha spec)
speed 25 mph
revs 4100
Calculated slip 30%
The slip is pretty high
Changing the pitch to 15 in lowers the slip to 20%, a more reasonable number.
I did lean something new form the Mercury racing information. When they enter diameter, they use 70% of the measured distance from the hub center to the tip of the blade. It's not clear if that adjustment is taken into account in the Mercury Prop calculator app.
One other thing to check: The pitch of the prop is often stamped on the center portion of the internal hub or on the inside of the hub. Numbers stamped on the outside of the main hub like 17M don't tell the whole story
Pitch 17in
gear ration 1.86 (Yamaha spec)
speed 25 mph
revs 4100
Calculated slip 30%
The slip is pretty high
Changing the pitch to 15 in lowers the slip to 20%, a more reasonable number.
I did lean something new form the Mercury racing information. When they enter diameter, they use 70% of the measured distance from the hub center to the tip of the blade. It's not clear if that adjustment is taken into account in the Mercury Prop calculator app.
One other thing to check: The pitch of the prop is often stamped on the center portion of the internal hub or on the inside of the hub. Numbers stamped on the outside of the main hub like 17M don't tell the whole story
is yours a 4 blade? Like to get an inexpensive prop 15 pitch 14 1/4 diameter to try it and have a spare......best place to shop props online?ocnslr said:
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ric2352 said:
I contacted Ken at Prop Gods, very helpful and informative. I bought a 4 blade from him and it has worked out great. My original 3 blade is now my spare. Might give him a shout.
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ric2352 said:
15 1/4 x 17 three blade was on it, went to a 15 1/4 x 16 Power Tech 4 blade. This is also a F225, a bigger motor than what you're running. I still say get with Ken, his recommendation was spot on with what I wanted from my prop. Prop Gods and Ken have been around awhile and are well respected. They know their stuff.
I believe that the inline F200 and your F225 have different gear ratios. The F225 has a 2.0 ratio and the I4 is 1.86
If so, your prop selection may not be suitable for the I4
If so, your prop selection may not be suitable for the I4