robalo evinrude setup

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  • robalo evinrude setup

    ken
    looking for some input with the setup of my boat. boat is a 2017 robalo 227 with an evinrude g2 250. here are latest performance numbers

    prop evinrude rx4 16p
    max rpm recorded 5850
    speed on gps 45mph

    This boat from new has had vibration issues which was greatly improved with the rx4 4 blade. However there is still a resonating sound in the hull which sounds like a low hum. the motor height is now at the top hole which puts the ventilation plate 1 3/4 inch above the keel.

    One thing that concerns me is there is a groco scoop which was installed by Robalo that is located 8 inch from the keel. I checked other r227's and they are located in the same spot which may be ok with the typical Yamaha that comes with this boat. The Yamaha vent plate as setup from factory is 1/2" above keel putting the prop a little deeper in the water. let me know what you think

    any input would be appreciated

    Tim
    Attached Files

  • #2
    Is it throughout the RPM range, or just at specific RPM?

    The RX4 is a very aggressive prop, and can tolerate high engine heights and dirty water, but it may just be humming cause the blades are breaking the surface, or that pickup is getting a little dirty water to the prop.

    What was the old prop? was that vibration worse? was it also slipping before. (I ask, because you said the RX4 is doing a lot better)

    Ken Reeves
    [email protected]
    941-735-5808

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    • #3
      Ken
      thanks for the response. The hum is through out the Rpm range, does mellow out about 4000 and then gets real loud when you open it up. the original prop was a 18p rebel and would vibrate and cause the back door to rattle. Did settle down above 4000 rpm. The 4 blade was a big improvement.

      from the photo what do you think of the engine height?

      also was thinking the 16p rx4 is not enough pitch for this boat was thinking of going up to 17 or 18 in a merc prop

      tjm

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      • #4
        ken, here is a photo of the water scoop. I was thinking of grinding the scoop section off as a first step.

        tjm
        Attached Files

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        • #5
          I wouldn't "think" that is close enough to cause it, but its close.
          I guess if you buy another intake, if you grind that one off and it doesn't solve anything, you could just reinstall a new one.
          Height looks pretty high, so it might just be breaking the surface. (runs fine, but makes noise)
          dropping the motor a hole would be interesting.

          Ken Reeves
          [email protected]
          941-735-5808

          Comment


          • #6
            ken
            at the lowest setting as it is. do you have a recommendation for a prop?

            tjm

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            • #7
              photo of side with groco scoop

              tjm
              Attached Files

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              • #8
                I don't have anything that is going to have better traction then that RX4, they are good props.
                You could try a higher pitch one, to get your RPM down if needed.

                Ken Reeves
                [email protected]
                941-735-5808

                Comment


                • #9
                  the next size up with an rx4 is an 18p. would that be to much?

                  i was thinking along the line of a merc rev4 or q4 17p

                  giving the performance numbers i have now where do think a 17p and 18p would bring me?

                  tjm

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                  • #10
                    I'd be looking carefully into the slip% numbers when it comes to Rev-4/Q4 and RX-4. I have a Suzuki-engine, and have played with some Suzuki and Solas props. I also think Solas is the actual maker of the Evinrude-props. I could be wrong, but that's what seems to be the case as far as i can see from number posted and other "things". They even come in exact the same box/packaging as a standard Solas/Rubex-prop. I also have a stock Rev-4- 21". Despite lower speed, it turns about 150 rpms more than a stock 21"pitch/15"dia 3-blade Solas prop. The same ratio goes for the oem Zuke 3x14,75x23. I think that also goes for the RX-4.

                    That said: I'm very excited with the Bravo1 versions from Merc Racing on my Suzuki. Currently I'm playing with height on a -FS. The XC-version (extra cupping) would probably beat even a Rev-4 in most regards. One bonus is the pitch-increments. (Or the XP (extra pitch) version of Rev-4) Easy to dial in, but costly.🙄

                    Fun fact: I'm slightly underpropped with my 21" Solas props. I'm a bit overpropped with my 26" FS -but it's not that bad: I'd probably reach 5700-5800rpm with the engine raised..(6K redline). And that was the plan: Not to hit the rev-limiter, but to have some solid numbers.(Couldn't find anybody running a Bravo 1 FS on a DF150 Zuke posting some decent numbers - hehe.) But I didn't expect this low slip% on a 2,50:1 Suzuki. Well ,well:..The bowlift combined with grip makes it worthwhile.( I/the boat liked it). Don't trust your pitch, nor your slip.😎

                    For the record:
                    Suzuki DF-150/20ft "bayboat"/moderate-V/2800lb: Bravo 1 FS 26"/ AV-plate 20mm/4/5" above keel: [email protected] 10-11% slip. The prop feels
                    "smooth" and do "lift" the bow/holds the bow up. I'm gonna rise the engine, and rpms should increase. Hopefully speed to. Slip also probably rise by a couple %.

                    And also for the record: Rev-4/21": [email protected] (underpropped): 7% slip.(Altough speed of boat has increased since new bottompaint - this was pre-paint and probably 1 mph off - but slip probably the same) - but I was close to the limiter with the 21" Rev-4.
                    Click image for larger version  Name:	image_10351.jpg Views:	6 Size:	1.63 MB ID:	88673
                    Attached Files
                    Last edited by Ibiza; 07-10-2020, 03:38 PM.

                    Comment


                    • #11
                      Ibiza is definitely correct, on all of that.
                      I kinda suspected Solas was making Evinrude props as well, they are really soft, and get super low slip numbers, but I have no knowlege of that being true, just suspicion based on performance. And now knowing they have the same boxes ha ha.

                      I would expect a 17 Q4 or Revolution 4 to get the same RPM as your 16 RX4. the 17 might actually turn more.
                      Would be interesting to try a 17 or 19, doesn't matter, just something different to see if that vibration goes away.

                      Did you grind off that intake yet?

                      Ken Reeves
                      [email protected]
                      941-735-5808

                      Comment


                      • #12
                        Ken thanks for the reply
                        need to get the boat out of the water to get at that scoop. just so happens i hit some submerged wood the other morning and now have small bend on one blade. really don" want to sink money into this prop for a repair

                        i would like to get the RPM down to about 5650 or 5700. you think my best shot is an 19p? My slip with the rx4 is about 6% what would you expect with an rev 4?

                        also seen on merc site the rev 4 has an 18p. if that info is correct could be the right fit.

                        let me know cost of prop and shipping to NJ. and exchange cost. May want to get two and send one back if that is possible.

                        tjm

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                        • #13
                          Ken certainly knows alot more abouts props than me, but I agree: First priority is to see if a Rev-4 adresses the main issue - vibrations.Secondly, I think Ken's right: A Rev-4/Q4 17" might turn more rpms - but it's not that important: You need a baseline with the Rev-4. The 18" is from Merc Racing and it's XP-range. Slightly more $, but it would be "zero-balanced" wich is a good thing. Your engine is good for 6K rpms, so you could probably try both 17"/19". And I think you're right: An 18" Rev-4 XP might just be spot on. It would probably not be a new 18" casting, but a worked 17" with sligtly more cupping - wich probably would be good with this high enginemounting. My wote goes for a 17" for a baseline.

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                          • #14
                            Here's my take on boxing: Evinrude vs. Solas:
                            Click image for larger version

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                            Attached Files

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                            • #15
                              Or the TBX-hub-kit versus the RBX-hub-kit:
                              Click image for larger version

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