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  1. #1
    rosey's Avatar
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    loss of top speed. Could it be the hull?

    So after putting the Solas impeller and a housing with a wear ring on I was tapping 71 on the speed o. that was in the intercoastal waterway with just slight chop as I would call it. Not white caps or glass just small little waves. I did not have my camera on me and no GPS yet. Last weekend out on the lake the wave conditions were just ever so slightly choppier, but I found a shoreline that was basically the same as intercoastal as far as i could remember. I could only hit about 62 on the speed o but the GPS registered 64.5. probably around 5 mph drop. The main difference is my Hull is all scratched up from sending it onto the beach at 70 mph...oops. My question is would the scratched up hull decrease top end that much? I mean it is like 80 grit from stern to keel. or maybe it is a combo of hull conditions and water conditions. i guess it could also be the dang little speed o that is messin with me.


    here is a picture of the water conditions on the lakeClick image for larger version. 

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  2. #2
    Jarrett's Avatar
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    Might have cracked the exit nozzle. Do you know it the ski was in the recall? Check that nozzle. Do you know what RPMs you are running and what was the air quiality like?

    I've heard racers say they sand the hull to get the gloss off of it to improve speed and handling. Who knows it that is true or not, but I've heard it said.

  3. #3
    Jarrett's Avatar
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    The more I think about it, it might just be the speedo. Depending on water, air quality, rider weight, riding style, gas level, 64.5 might be right for the ski.

    The trick with props is you have to pitch them for the RPMs that your ski produces in your environment. And environment makes a big diff. You can put a new "better" prop on and go slower if its not pitched right. If its knocking your RPMs down to say 7400, then it would go slower. But if you had it pitched to where it would spin at 7900-7950 RPM, you would be getting the most out of the ski/engine/prop. How do you know RPMs? Get an aftermarket tachometer. I use Tiny Tach, others use PET.

    Propping correctly is a big part of getting performance out of a ski.

  4. #4
    rosey's Avatar
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    Quote Originally Posted by Jarrett View Post
    The more I think about it, it might just be the speedo. Depending on water, air quality, rider weight, riding style, gas level, 64.5 might be right for the ski.

    The trick with props is you have to pitch them for the RPMs that your ski produces in your environment. And environment makes a big diff. You can put a new "better" prop on and go slower if its not pitched right. If its knocking your RPMs down to say 7400, then it would go slower. But if you had it pitched to where it would spin at 7900-7950 RPM, you would be getting the most out of the ski/engine/prop. How do you know RPMs? Get an aftermarket tachometer. I use Tiny Tach, others use PET.

    Propping correctly is a big part of getting performance out of a ski.
    Jerret,
    Thanks for the impeller tips but it had the same impeller on both runs. I did look at the rpm (stock gauge) at max speed and as far as i could tell it was the same, 8000 rpm's or so. I glanced over the nozzel after the beach action but not closely. Perhaps that is the problem because it did jump a couple of drift logs on the way up the beach. I will check it closer when I get home friday. Will it be obvious like at bolt mounts?
    The air quality was same. Only 2 weeks difference in texas... Still 95 deg and 80% humidity. I am thinking maybe the speed o got damaged if the nozzel is good.

  5. #5
    Jarrett's Avatar
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    Yeah, easy to throw off stock speedometer.

    I haven't seen a broken exit nozzle so far, so not exactly sure what they look like. The ones I've seen have been splits going from front to back.

    So you had a 71 MPH speedo reading with no GPS reading, then 62 MPH speed reading with a 64.5 MPH GPS reading? If so, it might have been going 64.5 both times on GPS. Or maybe a little higher on the 71 run if water and air were better. I ran with my brother's stock VXRs on the river last weekend and it was around 102-104 degrees and they were topping out around 64-65 MPH on GPS I think. This time of year in Texas makes skis sloooow. I'm ready for that first cold front in October/November to see what they do. One of my favorite days to GPS is the day after Thanksgiving. No one on the water at all and sometimes the air is around 65-70 with low humidity. Makes for some good GPS numbers

  6. #6

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    You might be scrubbing a few MPH with the Mickey Mouse ears.

  7. #7
    rosey's Avatar
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    Quote Originally Posted by Jarrett View Post
    Yeah, easy to throw off stock speedometer.

    I haven't seen a broken exit nozzle so far, so not exactly sure what they look like. The ones I've seen have been splits going from front to back.

    So you had a 71 MPH speedo reading with no GPS reading, then 62 MPH speed reading with a 64.5 MPH GPS reading? If so, it might have been going 64.5 both times on GPS. Or maybe a little higher on the 71 run if water and air were better. I ran with my brother's stock VXRs on the river last weekend and it was around 102-104 degrees and they were topping out around 64-65 MPH on GPS I think. This time of year in Texas makes skis sloooow. I'm ready for that first cold front in October/November to see what they do. One of my favorite days to GPS is the day after Thanksgiving. No one on the water at all and sometimes the air is around 65-70 with low humidity. Makes for some good GPS numbers

    Sadly i am thinking you are right. The ski prolly always topped out at 65, but i did not have the gps on the initial runs. The speed o is just not even worth having if thats the case. Its not like there is speed limits on the water. And it has a 5 mph bummer feeling when compared to gps. Day after thanksgiving will be here soon.

  8. #8
    YoYamma's Avatar
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    Quote Originally Posted by rosey View Post
    So after putting the Solas impeller and a housing with a wear ring on I was tapping 71 on the speed o. that was in the intercoastal waterway with just slight chop as I would call it. Not white caps or glass just small little waves. I did not have my camera on me and no GPS yet. Last weekend out on the lake the wave conditions were just ever so slightly choppier, but I found a shoreline that was basically the same as intercoastal as far as i could remember. I could only hit about 62 on the speed o but the GPS registered 64.5. probably around 5 mph drop. The main difference is my Hull is all scratched up from sending it onto the beach at 70 mph...oops. My question is would the scratched up hull decrease top end that much? I mean it is like 80 grit from stern to keel... it did jump a couple of drift logs on the way up the beach. I will check it closer when I get home friday.

    Rosey;
    if you ran the ski up on the beach and bounced over logs at 70 mph you may have damaged your:

    1. Impeller; get a flashlight and inspect closely for nicks, dings, etc.

    2. Intake grate; possibly cracked or damaged a bolt may be sheared or loose

    3. Speedo where is comes out of the ride plate

    4. Ride plate; inspect closely double-check all bolts, etc.

    5. Hull? Could be a hairline crack or something else you missed; inspect closely with flashlight

  9. #9
    rosey's Avatar
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    Quote Originally Posted by Corey R. View Post
    You might be scrubbing a few MPH with the Mickey Mouse ears.

    Lol. That was my brother wearing his brand new scorpions bandana... He lost it.

  10. #10
    rosey's Avatar
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    Quote Originally Posted by YoYamma View Post
    Rosey;
    if you ran the ski up on the beach and bounced over logs at 70 mph you may have damaged your:

    1. Impeller; get a flashlight and inspect closely for nicks, dings, etc.

    2. Intake grate; possibly cracked or damaged a bolt may be sheared or loose

    3. Speedo where is comes out of the ride plate

    4. Ride plate; inspect closely double-check all bolts, etc.

    5. Hull? Could be a hairline crack or something else you missed; inspect closely with flashlight

    The impeller looks prestine
    i did get a spall of the gelcoat about golfball size on the hull but put new resin on it and sanded. It is the smoothest part of the hull bottom now.
    i did not check the grate or the ride plate. I will definately do that.
    Thanks YoYamma

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