2011 SUNDANCE B20CCR with 90HP YAMAHA 4 stroke

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  • #31
    interesting that it ran smooth to 34 and the bow "dropped" then the porpoising started.

    You may actually need a bowlifting 3 blade that can hold it bow high and keep it there to avoid the porpoising.

    Possibly a Powertech PTR3, high rake bowlift.

    Ken Reeves
    [email protected]
    941-735-5808

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    • #32
      How would the holeshot be on something like that? I REALLY miss the way it got on plane with the SCD4 prop. This turbo still has a good bit of bow rise to it, similiar amounts of bowrise getting on plane as the michigan wheel aluminum, but it holds the stern up higher than the michigan wheel planing. Since I will be using it on the flats, I want something that will get on plane easily, and keep the stern up as much as possible.

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      • #33
        well the bowlifting prop probably wouldn't do as well down low, but might do better at the faster speeds and not porpoise as much.
        Just have to try it. The issues are a little odd, so its going to be one of those trial and error deals.

        Ken Reeves
        [email protected]
        941-735-5808

        Comment


        • #34
          The RXB4 props tend to pull like a higher pitch correct? I found a 16 pitch one for sale that is supposed to be new, but I'm worried a 16 might be to much pitch. I know the 17 pitch TURBO QUEST 4 is an inch to much pitch topping out at 5550-5600 RPM's, but top speed on it was the slowest of any I've ran. I can spin the 17 pitch 4 blade aluminum SOLAS right up to 5900, at 38 MPH when I'm light, or 5800 at 36 MPH loaded. Wondering if it's worth rolling the dice on this 16 pitch RXB4 or not. Hoping come the 1st of JUNE, I can have some time to use my boat before I have hand surgery.

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          • #35
            Yeah, expect about Zero slip on an RXB4. they are normally between negative 2 and 3% slip

            Ken Reeves
            [email protected]
            941-735-5808

            Comment


            • #36
              I hate to admit it, but I just now got the PERMATRIM installed and ran it. It definately helped with the porpoising. I was running my SOLAS AMITA 4 that ran good before except for some porpoising on the top end, and I oculd plant the bow down solid at WOT, actually picked up a little with the fin VS without. It had no problems pushing it up to 38 whereas it would top out at 36 loaded like I was before. I think the increase in speed is because I can now stay in it without it going on springs and bouncing away. I had to actually trim it up some this time because it planted the bow so tight at WOT. The trim is VERY sensative now as the slightest change moves the bow ALOT. I also found now the engine needs to be 1 1/2 inches higher than before so to get teh plate out of the water and make it run smoothly without alot of spray.

              Now it's time to find the right prop to compliment it as this SOLAS runs OK, but even with the foil has lackluster performance getting on plane. I'm torn between the SCD4 16 pitch or a RXB4 15 pitch. I want a SOLID holeshot out of it as I will be trying to get on plane in shallow water most of the time, but I also want good cruise performance as the majority of my boating will be family cruising with it for now. Which would you reccomend going with. The SOLAS AMITA 4 aluminum I now have on topped out around 38-38.5 at 6000 RPM's once I got the engine height where it wants to be at. The 19 SCD4 I ran before topped out at 36 at 4950, but that was without the foil and just me in the boat. The factory reccomended prop is a 16 pitch YAMAHA 3 blade performance series prop, and the test reports say 39.7 MPH at 5900. So which one would you reccomend?

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              • #37
                The closest thing to the yamaha Performance 3 blade would be the Powertech PTR3 which is a bowlifting 3 blade, and I don't think you've tried one yet.

                But for strong holeshot, the RXB4 would be my choice.

                Ken Reeves
                [email protected]
                941-735-5808

                Comment


                • #38
                  Got out yesterday and ran the rxb4 16 pitch. The prop hooks up, theres no question about that. The holeshot wasn't bad with it, but it still lifts the bow more than I would like, and the stern dropped down some planing. At cruise it ran nice, good hookup, could jack the engine way up with no ventilation problems, but it just doesn't feel right to me. The down side is I lost 3.5MPH top end from the 4 blade aluminum 17 pitch SOLAS. The SOLAS topped out at 38.5MPH at 6000 RPM's, the RXB4 only topped out at 35MPH without porpoising, got it up to 36, but she was bouncing pretty bad doing it. It also took alot of trim to get the speed up, but as soon as it got up to speed, I had to trim down or else it would go to porpoising. Thinking I want to try the SCD4 in a 16 pitch next. I'm leaving the end of next week on vacation, so I'll try and give you a call before I leave to try and work out the details.

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                  • #39
                    Sounds like a plan.

                    Ken Reeves
                    [email protected]
                    941-735-5808

                    Comment


                    • #40
                      I checked my notes, and I was wrong about the RXB4's WOT RPM's, it was 5350-5400 at 35 MPH. I got the SCD4 16 pitch on Friday, hoping I can get out for a quick run tomorrow sometime if I can dodge the rain and try it out. One thing I noticed about the 16 pitch SCD4 is how little cup it has in it. The 19 of yours I tried before had ALOT more cup in it than this 16 has. Hoping it works out, otherwise I'll kick myself for not going with a 17.

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                      • #41
                        yep, they are all a little different.

                        Ken Reeves
                        [email protected]
                        941-735-5808

                        Comment


                        • #42
                          OK, finally got away and ran the 16 pitch scd4. Top speed is 36-36.5 mph at 5900-5950, so prop slip seems to be pretty good around 6%(this was just me, full tank of fuel, and a few fishing poles, so fairly light load). The boat actually gets up on plane now fairly easily. If I ease it up, it just about comes up flat with no stern squat or bow rise, just basically lifts up, but if I hammer down I get a little stern squat and some bow rise, but neither are very much. With the scd4 and permatrim on it, porpoising is hardly noticeable now unless I get ridiculous with the trim. The bow dropping around 34 still happens and will porpoise still, but I can trim it now and keep it under control. Cruise is pretty good as well. A few more rpm's at each given speed than the 17 pitch aluminum, but I can hold it on plane down to about 12 mph now, at 17-18 I'm turning around 3600, and can trim it so it did well in a chop(pretty good for an 8' wide skiff), or on calm waters bump it up and cruise in the 20-25 range easily enough. Another BIG bonus is the reduction in steering torque. Even trimmed in all the way you don't have to fight the wheel to go left. Overall I'm very happy with how the boat feels and handles now, my only comlaint is I lost top end speed vs the 4 blade solas amita aluminum prop.

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                          • #43
                            amazes me that Amita 4 was faster then the Stainless props, but sometimes it just works that way.

                            Ken Reeves
                            [email protected]
                            941-735-5808

                            Comment

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