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  1. #1
    rob2337's Avatar
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    Sl Sponsons - Porpoising Problem

    I have a 94 750 and 650 and I am getting really tired of them porpoising. I can only cruise at around 4000rpms before they start jumping and the pump loses its hook-up. I need to wait till evening to have glass water.

    After reading around, I know I need sponsons. Now, my question is if SLT sponsons will work ( or any other sponsons sea-doo, etc). I saw a pair of SLT sponsons for sale, and they seem to have a bolt through design which i prefer, as opposed to using studs or epoxying in inserts.

    If I use SLT sponsons, do I mount them in the same location as regular sl sponsons as indicated in a bulliten in the tech section?

    At last does anyone have any sponsons for sale that would do the trick?


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    SLT will work, I'm using them right now with no issue.

    Yes, same location.

    I have some SLT sponsons with the threaded inserts for $30 plus shipping if interested.

  3. #3
    2000 pro 785 (son's) 1998 pro 785 (dads) old guy in mich's Avatar
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    not positive they have an application but running beach house on both 785's. no porposing and on rails for tracking in turns. not great for play, just too aggresive. super adjustable too. randy had some listed at his site too. look like beach house design.
    Watcon.com
    Hull - Beach House Sponsons

  4. #4
    AWA Member 32DegH2O's Avatar
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    Sponsons (or lack there of) is not your issue causing the porposing...it's your ride plate that you need to change. Sponsons will help you turn and they keep you balanced more side to side when going through waves but they have no real value for porposing issues.

    Edit: no real value for porposing issues on the three seater watercraft.
    Last edited by 32DegH2O; 07-02-2008 at 08:35 PM.

  5. #5
    ShaneG's Avatar
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    Dude I had the same problem until I got the long OP ride plate from Ken. I have sponsons as well, but even before I added those to help with high speed tracking, the OP ride plate fixed the issue. You may lose a few MPH's on top end as it plants the nose, but saving the wear and tear on your Kidneys is well worth a few MPH's. Just my .02.

    Shane

  6. #6
    rob2337's Avatar
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    Ok, I thought I read some post saying sponsons will stop porpoising, but you guys are the experts. Just fyi, my 750 has adjustable trim, and I keep it pointed down, and it still jumps in slightly rough water. I don't care if I give up some top speed, as the water around me is always rough, preventing me from opening it up.

    So where would I start looking for a ride plate. Does anyone have one for sale?

    Also, I am assuming that once I have a longer ride plate, the pump will stay hooked up better without the need of a new grill.

  7. #7
    100 MILES OF HEAVEN AND I AM SMACK IN THE MIDDLE KEYZBUM's Avatar
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    OK I will throw my head in to be cut off
    I am one of those people that posted about sponsons and porpising,,
    but mine was a little diff.
    i had stated on my pro785 i took the sponsons off to try and pick up 2 mph on the gps WRONG
    IT BOUNCED LIKE MY 95 SL750 DID FOR YEARS,tried all the trim settings
    but still couldnt break 55mph jump in the water screw the sponsons back on
    63 mph
    oh and i just stepped the sponsons on my gpr to stop the porpising
    just my 2 pennys
    mattman

  8. #8
    AWA Member 32DegH2O's Avatar
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    Keyzbum...I'm not surprised that sponsons on your pro helped a lot due to the length, weight and design of the pro hull...and yes technically sponsons do help with porpoising on all models but it's just not as a prevalent impact on the three seater watercrafts. It really becomes a ride plate issue in this case or a truing of the hull due to age/warping...causing slight waves along the surface of the hull.
    Last edited by 32DegH2O; 07-02-2008 at 08:37 PM.

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by KEYZBUM View Post
    OK I will throw my head in to be cut off
    I am one of those people that posted about sponsons and porpising,,
    but mine was a little diff.
    i had stated on my pro785 i took the sponsons off to try and pick up 2 mph on the gps WRONG
    IT BOUNCED LIKE MY 95 SL750 DID FOR YEARS,tried all the trim settings
    but still couldnt break 55mph jump in the water screw the sponsons back on
    63 mph
    oh and i just stepped the sponsons on my gpr to stop the porpising
    just my 2 pennys
    mattman
    I agree 100%

    JetskiMN, he only mentioned SLT because he saw them for sale. I believe he has a SL that is porpoising badly, which the SLT sponsons will help tremendously. It did on mine. I can't go wot with 2 people without them. Porpoises too badly.

  10. #10
    AWA Member 32DegH2O's Avatar
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    Gotcha...just noticed that from your pointing it out...my bad! Although I still believe a ride plate will net better results for posposing than sponsons. Adding sponsons is also a vast improvement for handling. I would do both items in this case.

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