Top Speed

[JeffRad54]

I've only been able to achieve 37 mph with about 30 gallons of fuel, 30 gallons of water, an empty waste tank and just me onboard (another 175 lbs.).

I've played with the motor trim (Yamaha 300 OB) and find the best setting is full down.
My dealer said not to use the trim tabs except for unbalanced loads because they will just kill my mpg.

Any advice?

 

[baz]

My 2018 R27/OB (Yamaha F300) gave me a WOT speed of 38 mph with just me onboard. The boat had bottom paint and a full cockpit enclosure as well as an inflatable kayak installed on the cabin's roof rails. I always had the trim set at 3 bars and never ever changed it.

What exactly are you wanting wrt "advice" ?

 

[JeffRad54]

Well, the advertised best speed is 41, with more weight than I had. So I want to know how to best achieve that speed. Also, regarding trim tabs, was my dealer correct with his advice not to use them except for lateral balance?

 

[baz]

Goto https://yamahaoutboards.com/en-us/h...300-(4-2l)/pb_rgt_r-27_f300uca_2017-06-28_owa for the info you probably need as a comparison. It shows at 5900 RPM the speed attained was 42.3 MPH. As I said, I was only able to get around 38 MPH as best I can recall. Now if I made a mistake here thinking the display was in MPH but was a GPS speed of 38 kts then this would mean 42.6 to 43.7 MPH, and that does closely correlate to the Yamaha's performance data for the RT27/OB with the F300 motor.

I quite likely did not have a full tank of fuel and there was little to no wind and a very calm sea. I was solo as well.

When I mentioned trim of 3 bars I was referring to the motor trim up/down and not the trim tabs which I had in the fully up position.

 

[ixlr8]

With clean hull, no bottom paint, full fuel, full water, no black water, with 2 people on board I attained 41 mph several times with my 27OB. I was trailering the boat at that time. I then put the boat in a slip and after 6 weeks in the water, the growth on the hull reduced my top speed to 28 mph. It doesn't take much 'stuff' on the hull to slow the boat down.

 

[Matty]

A few mph coould easily be attributable to conditions. Wind? Water moving with or against you? Do you have a generator and test boat did not? Easily could come up with a few factors to impact the top speed.

Cannot resist - ixlr8 says he was trailing the boat at the time he got 41 mph. Seems you should have been able to get over 60 while trailering! :lol:

 

[ixlr8]

Cannot resist - ixlr8 says he was trailing the boat at the time he got 41 mph. Seems you should have been able to get over 60 while trailering! :lol:

Trailing??? I was trailering the boat to and from the water, I didn't have the boat in a slip or on a mooring. 🙂

 

[Matty]

I need to check my typos and spelling when making jokes. Good comeback though.

 

[JeffRad54]

Goto https://yamahaoutboards.com/en-us/h...300-(4-2l)/pb_rgt_r-27_f300uca_2017-06-28_owa for the info you probably need as a comparison. It shows at 5900 RPM the speed attained was 42.3 MPH. As I said, I was only able to get around 38 MPH as best I can recall. Now if I made a mistake here thinking the display was in MPH but was a GPS speed of 38 kts then this would mean 42.6 to 43.7 MPH, and that does closely correlate to the Yamaha's performance data for the RT27/OB with the F300 motor.

I quite likely did not have a full tank of fuel and there was little to no wind and a very calm sea. I was solo as well.

When I mentioned trim of 3 bars I was referring to the motor trim up/down and not the trim tabs which I had in the fully up position.

My max RPM has been 5600. My GPS speed was in MPH.

 

[JamesTXSD]

Goto https://yamahaoutboards.com/en-us/h...300-(4-2l)/pb_rgt_r-27_f300uca_2017-06-28_owa for the info you probably need as a comparison. It shows at 5900 RPM the speed attained was 42.3 MPH. As I said, I was only able to get around 38 MPH as best I can recall. Now if I made a mistake here thinking the display was in MPH but was a GPS speed of 38 kts then this would mean 42.6 to 43.7 MPH, and that does closely correlate to the Yamaha's performance data for the RT27/OB with the F300 motor.

I quite likely did not have a full tank of fuel and there was little to no wind and a very calm sea. I was solo as well.

When I mentioned trim of 3 bars I was referring to the motor trim up/down and not the trim tabs which I had in the fully up position.

My max RPM has been 5600. My GPS speed was in MPH.

If the WOT redline is 5900 RPM and you are getting 5600, you are likely slightly over-propped.

 

[JeffRad54]

Goto https://yamahaoutboards.com/en-us/h...300-(4-2l)/pb_rgt_r-27_f300uca_2017-06-28_owa for the info you probably need as a comparison. It shows at 5900 RPM the speed attained was 42.3 MPH. As I said, I was only able to get around 38 MPH as best I can recall. Now if I made a mistake here thinking the display was in MPH but was a GPS speed of 38 kts then this would mean 42.6 to 43.7 MPH, and that does closely correlate to the Yamaha's performance data for the RT27/OB with the F300 motor.

I quite likely did not have a full tank of fuel and there was little to no wind and a very calm sea. I was solo as well.

When I mentioned trim of 3 bars I was referring to the motor trim up/down and not the trim tabs which I had in the fully up position.

My max RPM has been 5600. My GPS speed was in MPH.

If the WOT redline is 5900 RPM and you are getting 5600, you are likely slightly over-propped.

WOT in the Yamaha Manual is a range... 5000 to 6000. What does that tell me?

I must assume (?) that the boat, motor, and prop have been properly matched.

 

[BB marine]

WOT in the Yamaha Manual is a range... 5000 to 6000. What does that tell me?

I must assume (?) that the boat, motor, and prop have been properly matched.

If your rpm of 5600 is, just you in the boat, lightly loaded, tabs up motor trimmed for optimal performance. Your over propped. Light load, boat trimmed properly ( Did your dealer demonstrate proper trimming for different rpm ranges?) the rpm should be in the upper range of specification even 100rpm over 6100rpm would be completely acceptable. The reason for this is when your loaded, extra passengers, full water, gas, beer and ice, your rpm will then be still in the recommended rpm range preferably in the middle 5500/5600 would be perfect full load. Under propping by a couple hundred light load is fully acceptable in larger outboard powered boats. Honestly before I would change props, I would advise playing with the boat, change trim angles on the engine while cruising and trim tab adjustments. You may find that you are able to pickup 300rpm or more if you air the hull out a little more. You should be able to feel it when it's right. If your rpm is still 5600rpm theoretically dropping 2" of pitch should give you 300 rpm more.

 

[JeffRad54]

WOT in the Yamaha Manual is a range... 5000 to 6000. What does that tell me?

I must assume (?) that the boat, motor, and prop have been properly matched.

If your rpm of 5600 is, just you in the boat, lightly loaded, tabs up motor trimmed for optimal performance. Your over propped. Light load, boat trimmed properly ( Did your dealer demonstrate proper trimming for different rpm ranges?) the rpm should be in the upper range of specification even 100rpm over 6100rpm would be completely acceptable. The reason for this is when your loaded, extra passengers, full water, gas, beer and ice, your rpm will then be still in the recommended rpm range preferably in the middle 5500/5600 would be perfect full load. Under propping by a couple hundred light load is fully acceptable in larger outboard powered boats. Honestly before I would change props, I would advise playing with the boat, change trim angles on the engine while cruising and trim tab adjustments. You may find that you are able to pickup 300rpm or more if you air the hull out a little more. You should be able to feel it when it's right. If your rpm is still 5600rpm theoretically dropping 2" of pitch should give you 300 rpm more.

Wow. Good info there and I appreciate it!
No, the dealer did nothing about demonstrating how trim affects speed, RPM or anything like that. I will speak with him about that.
Finding my 'sweet spot' is a bit difficult for me. I'm on the Mississippi with a 3 to 4 knot current in spots. Confused waters, you know. I will do as you say, play with the motor trim and trim tabs and get back to you.
By airing out the hull, I think you mean more bow up?
Not to disagree with anything you are saying, but the prop pitch is what the factory supplied. Would I be wrong in thinking they know best what prop is suitable? Please advise.

 

[BB marine]

By airing out the hull, I think you mean more bow up?
Not to disagree with anything you are saying, but the prop pitch is what the factory supplied. Would I be wrong in thinking they know best what prop is suitable? Please advise.

Airing out is trimming the bow up using the engine trim. Reducing wetted surface contact normally increases speed.

You are correct that the prop supplied by the Factory should be the right prop. Unfortunately that still requires a check. That is part of the delivery process. The servicing technician confirms that the correct prop was sent with the boat, the engine mounting elevation is correct ( Engine mounting hole used determines how high the ventilation plate sits above the bottom of the boat) The question is did the technician at the factory mount the engine in the right mounting hole? Did the technician install the right prop for the R27 ? The answers to this are probably yes but did the dealer give you the information stating when the boat was rigged and test run it performed maintaining ???? rpm. Do you feel confident that the dealer did all pre delivery inspections? From your comments on TugNuts I would say no. Verify prop installed Dia X pitch, Verify ventilation plate height above the bottom of the boat and record the mounting hole used. Test run the boat recording wind, current, water conditions (waves). Record WOT with current and against current. Adjust Trim tabs and engine trim to get the best rpm and speed. Trim tabs down and motor tucked down can reduce max RPM by 400 to 500 RPM WOT. This makes a planing hull plow a lot of water. After you record the information and if you find the numbers are below the publicized performance data equivalently rigged and weight. Talk to your dealer. Every boat built is not always the same. I worked for a Sea Ray dealer and delivered a lot of 26' Sundancers (Very popular model in the 90's) Sea Ray provided the correct tested prop with every boat. Most of the time the designated prop performed flawlessly. There were a few that this was not the case. Some required re-propping. My guess is you have the right prop, engine is mounted correctly, you just need to get use to the boat. I would still go through the steps to confirm that.

 

[JeffRad54]

By airing out the hull, I think you mean more bow up?
Not to disagree with anything you are saying, but the prop pitch is what the factory supplied. Would I be wrong in thinking they know best what prop is suitable? Please advise.

Airing out is trimming the bow up using the engine trim. Reducing wetted surface contact normally increases speed.

You are correct that the prop supplied by the Factory should be the right prop. Unfortunately that still requires a check. That is part of the delivery process. The servicing technician confirms that the correct prop was sent with the boat, the engine mounting elevation is correct ( Engine mounting hole used determines how high the ventilation plate sits above the bottom of the boat) The question is did the technician at the factory mount the engine in the right mounting hole? Did the technician install the right prop for the R27 ? The answers to this are probably yes but did the dealer give you the information stating when the boat was rigged and test run it performed maintaining ???? rpm. Do you feel confident that the dealer did all pre delivery inspections? From your comments on TugNuts I would say no. Verify prop installed Dia X pitch, Verify ventilation plate height above the bottom of the boat and record the mounting hole used. Test run the boat recording wind, current, water conditions (waves). Record WOT with current and against current. Adjust Trim tabs and engine trim to get the best rpm and speed. Trim tabs down and motor tucked down can reduce max RPM by 400 to 500 RPM WOT. This makes a planing hull plow a lot of water. After you record the information and if you find the numbers are below the publicized performance data equivalently rigged and weight. Talk to your dealer. Every boat built is not always the same. I worked for a Sea Ray dealer and delivered a lot of 26' Sundancers (Very popular model in the 90's) Sea Ray provided the correct tested prop with every boat. Most of the time the designated prop performed flawlessly. There were a few that this was not the case. Some required re-propping. My guess is you have the right prop, engine is mounted correctly, you just need to get use to the boat. I would still go through the steps to confirm that.

You've given me a lot to think about and do. Thanks very much for the advice. Much appreciated.

 

[JeffRad54]

BB Marine,

I've found the best trim for top speed and top RPM. As you suggested, I experimented.
With a 5 mph current, I achieved 38 mph upstream and 43 mpg downstream averaging 40.5 with a dirty hull.
I'm good with that.

Thanks very much for your help.

Jeff