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  #11  
Old 04-29-2018, 12:50 PM
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mr yukon mr yukon is offline
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Unhappy answer about boat speed

I have a 2018 1900 TYEE with 200 L4 VERADO full tank and 3 people with gear 42 MPH GPS WOT standard aluminum prop! Should I be getting higher speed or is it because motor only has 2.5 hrs on it?
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  #12  
Old 04-29-2018, 06:01 PM
Darrenf442 Darrenf442 is offline
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Originally Posted by mr yukon View Post
I have a 2018 1900 TYEE with 200 L4 VERADO full tank and 3 people with gear 42 MPH GPS WOT standard aluminum prop! Should I be getting higher speed or is it because motor only has 2.5 hrs on it?
From everything ive ever read you have to much boat and hp for an aluminium prop. Your likely flexing the blades . Run your numbers on a prop slip calculator. ideally you want no more then 10% slip.



http://www.mercuryracing.com/prop-slip-calculator/
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  #13  
Old 04-29-2018, 06:45 PM
Waxy Waxy is online now
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Originally Posted by JohnN View Post
I'm not an expert by any stretch, but if one setup has more prop slip than the other it will be slower. Plus, it rarely seems like you can get two boats that are setup "exactly the same" to go the same speed.
This is the answer.

Go to a prop slip calculator and punch in the numbers. You might be surprised at how much the slip percentage affects max speed. It can easily be 5 mph or more.

http://www.mercuryracing.com/prop-slip-calculator/

Reducing slip is partially a hull and setup issue, but bottom line is that it takes HP.

Waxy
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  #14  
Old 04-29-2018, 06:59 PM
Darrenf442 Darrenf442 is offline
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You do NOT need to run max rpm to get max speed. I only run a 115 but my rpm range is 5800-6400. I was hitting a max speed of 42 mph at 5850 rpm with only 7% slip. so right at the bottom of the rpm range.

For some reason i now run 6050 rpm and still 42 mph.
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  #15  
Old 04-29-2018, 07:58 PM
Kevin23 Kevin23 is offline
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Originally Posted by Waxy View Post
This is the answer.

Go to a prop slip calculator and punch in the numbers. You might be surprised at how much the slip percentage affects max speed. It can easily be 5 mph or more.

http://www.mercuryracing.com/prop-slip-calculator/

Reducing slip is partially a hull and setup issue, but bottom line is that it takes HP.

Waxy

Hmm. Something fishy is going on here. Either the GPS on both of my sonars and my phone is off, my tach is off, or merc is off. It says with my motor and prop, and 0% slip I max at 45mph but I get 48 with a super light load, it's touched 50 before on a light chop. Interesting. I'm not hitting rev limiter so my RPM can't be that far off, merc says to hit 48 with 0 slip I would be running 6250rpm which should trip the rev limiter (I never go past 6000 on the tach, I am very cautious of that).
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  #16  
Old 04-29-2018, 08:02 PM
Waxy Waxy is online now
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Quote:
Originally Posted by Darrenf442 View Post
You do NOT need to run max rpm to get max speed. I only run a 115 but my rpm range is 5800-6400. I was hitting a max speed of 42 mph at 5850 rpm with only 7% slip. so right at the bottom of the rpm range.

For some reason i now run 6050 rpm and still 42 mph.
True, but maybe not ideal.

Lugging a motor or running at the bottom end of the RPM range at WOT is generally not good for it. In the case of the Verados, they tend to run best at around 6300 RPM.

The biggest reason to be running near the top of the RPM range at WOT is for overall performance. If the top speed is equal at WOT between a 19 pitch prop running at 6300 RPM and a 21 pitch prop at 5850 RPM, your overall performance, especially holeshot, will be better with the 19 and it will be less sensitive to changes in load or conditions.

Waxy
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  #17  
Old 04-29-2018, 08:07 PM
Waxy Waxy is online now
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Originally Posted by Kevin23 View Post
Hmm. Something fishy is going on here. Either the GPS on both of my sonars and my phone is off, my tach is off, or merc is off. It says with my motor and prop, and 0% slip I max at 45mph but I get 48 with a super light load, it's touched 50 before on a light chop. Interesting. I'm not hitting rev limiter so my RPM can't be that far off, merc says to hit 48 with 0 slip I would be running 6250rpm which should trip the rev limiter (I never go past 6000 on the tach, I am very cautious of that).
Gear ratio youíre using correct?

The most likely scenario is your prop isnít true to pitch, or has added cup, which has the same affect as added pitch.

Either way, it sounds like youíre running pretty close to perfect. 0% slip is only possible in theory lol.

Waxy
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  #18  
Old 04-29-2018, 08:10 PM
Kevin23 Kevin23 is offline
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Quote:
Originally Posted by Waxy View Post
True, but maybe not ideal.

Lugging a motor or running at the bottom end of the RPM range at WOT is generally not good for it. In the case of the Verados, they tend to run best at around 6300 RPM.


Waxy
For the 4 strokes as well. Both the dealer and the maintenance shop have been quick to comment how great of a motor the merc 4s is, and to make sure to run it at the top 400rpm if you are above 1/4 throttle. They are designed to run at the top of the RPM range and that's where you will have the least amount of issues regarding longevity.
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  #19  
Old 04-29-2018, 08:49 PM
Kevin23 Kevin23 is offline
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Never mind, I am a confirmed idiot. My gear ratio is 2.07, had to go out and look. Now it comes up 8% slip at 48mph
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  #20  
Old 05-01-2018, 07:02 AM
Waxy Waxy is online now
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Originally Posted by Kevin23 View Post
Never mind, I am a confirmed idiot. My gear ratio is 2.07, had to go out and look. Now it comes up 8% slip at 48mph
Ha. Simple mistake for sure, we've all been there.

Sounds like you've got it really nicely dialed in.

Waxy
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