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  1. #1
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    Question Has anyone tried this?

    Here is 2 questions to all with GPR's that have done this procedure.

    1Q: If I step my OEM sponsons (front of craft up most position and back most down) What advantages will I see in handling or mph gains?

    2Q: If I put washers under the OEM trim tabs to angle them with the rideplate will this help me achieve a better top end speed?


  2. #2
    philip_gpr's Avatar
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    1Q: If I step my OEM sponsons (front of craft up most position and back most down) What advantages will I see in handling or mph gains?

    ski will bounce less (lees porpoising)

    2Q: If I put washers under the OEM trim tabs to angle them with the rideplate will this help me achieve a better top end speed?

    ski handles terrible, more porpoising

    my suggestion is 2 washers under all 8 bolts -
    ski will bounce less (lees porpoising)

  3. #3
    Like a chimp with a ball-peen hammer smackwave's Avatar
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    What Philip said, just adding that stepping the sponsons scrubs a bit of speed over sponsons in the up position. It's the easiest way to cure porpoising, though.

    Trimming the tabs also helps with porpoising, but also scrubs a bit of speed. I've not had luck with staggering the stock tabs, but there are plenty of setups with staggered stock or aftermaket tabs that work very well.

    Two things about shimming the tabs, though... the stock plastic tabs on the 1300 are wobbly garbage and should be replaced with stock metal tabs from earlier years or after market tabs, and all washers are not created equal. The washers I ordered with the longer allen bolts I use when shimming tabs are .055" thick. Since the stock tabs can't be shimmed much more than .110" before hitting the sponsons and I wanted to shim them as far as I could that worked out well for me. However, I have other washers that measure .020" and would have only given me .040" with two washers. Even these small differences make a significant difference in the handling and top speed of the GPR.

    Finally, it sounds like you're trying to reinvent the wheel. The search feature on this forum can be your best friend. Use it, be patient, and read up on what others have said and done.

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