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  1. #1
    way2fast's Avatar
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    Questionable GPS ??

    Our club had it's second annual River Rally this past weekend. A couple of local dealers brought skis for the public to demo. I had my Garmin etrex GPS unit with me. I had used this same unit along with the in dash Norskog GPS digital speedometer in my STV race boat. Both units were always right on the money, reading identical speeds. The etrex also reads the same speed as does my car speedometer.

    I had the etrex with me when I tested a few of the skis at the rally. A Yammi VX 110 hp ski ran at 52mph with a nearly full tank. The Yammi FX HO ran 59mph. The air temp was in the mid 80's, water temp the same and the sea had a 1 foot chop. These speeds recorded seem to be in the realm of what these skis should run. Then I took a friends red Ultra 250 out. He had a Garmin GPS attached to the glove box. It was an upper level model compared to my etrax. The top speed of his Ultra was 62.8 on his GPS while mine read 67.3 (not 100% sure of the tenths..bad memory) He had 1/2 tank of fuel. Now here is where it gets interesting. The dealer demo blue Ultra 250 that was there was faster than my friends ski. I didn't get to GPS it but I ran another friends stock 15F against this quicker Ultra and couldn't believe how close the race was. The Ultra jumped me by a ski length from a dead stop, then slowly pulled about 3 lengths ahead....and kept that distance for the length of the race. My GPS said that the 15F was running 68.3 !! That seems hard to believe ! I would never have thought a 15F could run so close to the big boys if I wasn't the one riding it. The question is, whos GPS was giving the right speeds? Was mine reading 4 1/2 mph fast or was his slow?? Either way, the 15F was a real surprise.

    The Yammi FX HO (160hp) rode a lot higher in the water than did the Ultras, yet it was dry and comfortable. With 250 hp, I think this would be the ski to beat in a battle of the barges !!



    Richard


  2. #2

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    Yeah, my buddy's FX HO is enjoyable to ride. I could fall asleep sitting in that seat, it's the cruiser model, but it still hauls decent ass for what it is.

  3. #3
    Silence! I Keel You! earthshaker's Avatar
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    Quote Originally Posted by way2fast View Post
    Our club had it's second annual River Rally this past weekend. A couple of local dealers brought skis for the public to demo. I had my Garmin etrex GPS unit with me. I had used this same unit along with the in dash Norskog GPS digital speedometer in my STV race boat. Both units were always right on the money, reading identical speeds. The etrex also reads the same speed as does my car speedometer.

    I had the etrex with me when I tested a few of the skis at the rally. A Yammi VX 110 hp ski ran at 52mph with a nearly full tank. The Yammi FX HO ran 59mph. The air temp was in the mid 80's, water temp the same and the sea had a 1 foot chop. These speeds recorded seem to be in the realm of what these skis should run. Then I took a friends red Ultra 250 out. He had a Garmin GPS attached to the glove box. It was an upper level model compared to my etrax. The top speed of his Ultra was 62.8 on his GPS while mine read 67.3 (not 100% sure of the tenths..bad memory) He had 1/2 tank of fuel. Now here is where it gets interesting. The dealer demo blue Ultra 250 that was there was faster than my friends ski. I didn't get to GPS it but I ran another friends stock 15F against this quicker Ultra and couldn't believe how close the race was. The Ultra jumped me by a ski length from a dead stop, then slowly pulled about 3 lengths ahead....and kept that distance for the length of the race. My GPS said that the 15F was running 68.3 !! That seems hard to believe ! I would never have thought a 15F could run so close to the big boys if I wasn't the one riding it. The question is, whos GPS was giving the right speeds? Was mine reading 4 1/2 mph fast or was his slow?? Either way, the 15F was a real surprise.

    The Yammi FX HO (160hp) rode a lot higher in the water than did the Ultras, yet it was dry and comfortable. With 250 hp, I think this would be the ski to beat in a battle of the barges !!



    Richard
    Y Richard, i also suspect wierd readings. Here's the novice scoop on GPS models within Garmin as i understand it: The plain jane etex has a wafer antenna and can only pick up a few sattelites, unlike the 60hcx (or whatever the top 60 series letters are) has Quad antenna which apparently pics up more sat's. Then there is the more featured etrex models such as the vista cs that has the wafer antenna, but is "WAAS" capable....the vista csx however has one of those quad antenna's as well.

    I suspect slightly diff readings, but who knows. I do know the more sat's you're linked to, the more accurate for position, but dunno if it can affect a reading for speed.

  4. #4

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    I believe it could cause an error in speed. If I'm locked in on 8 sats I can get a location of + or - 16 feet. If your only getting 4 sats, that's usually around + or - 50 feet location.

    That's standing still, adding motion of 65mph in there, you might be talking more of a difference with the one carrying 4 sats.

    Might be a question to ask Garmin or Lowrance.

  5. #5

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    Lightbulb

    I have a Street Pilot 2720 and a 60CSx and they both read the same.
    I know the 60CSx will pickup anywhere from 4 to 9 sattilites at a time.
    I think your etrex would be less accurate compared to the higher end units due to the antennas..

  6. #6
    Silence! I Keel You! earthshaker's Avatar
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    Quote Originally Posted by Big Red Monster View Post
    I have a Street Pilot 2720 and a 60CSx and they both read the same.
    I know the 60CSx will pickup anywhere from 4 to 9 sattilites at a time.
    I think your etrex would be less accurate compared to the higher end units due to the antennas..
    One of these times we need to hook up at the lake and check'em.

  7. #7

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    Cool

    Quote Originally Posted by earthshaker View Post
    One of these times we need to hook up at the lake and check'em.
    What lake. Only on Saturday too. My honey doo day is Sunday...

  8. #8
    Silence! I Keel You! earthshaker's Avatar
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    Quote Originally Posted by Big Red Monster View Post
    What lake. Only on Saturday too. My honey doo day is Sunday...
    I'll pm you tomorrow or the next with the tour schedule.

  9. #9

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    Wink

    Quote Originally Posted by earthshaker View Post
    I'll pm you tomorrow or the next with the tour schedule.
    Well alrighty then....

  10. #10
    Beagleman62's Avatar
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    I have the Etrex Vista cx. I don't know how accurate it is compaired to other units but when mounted in my truck, it reads dead on with my speedo. It is supposed to be able to lock onto 12 satilites but don't ever see it lock onto more than 6 or so. It's also WAAS enabled.

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