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  1. #1

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    Question How does OPAS work?

    I could not post in the FAQ section so I put it here.

    I am just in the process of rectifying a problem with the OPAS on my 03 GTX and I just want to get a second opinion on how the OPAS system works.

    My ski pulls to the left and is not very stable on the water. I can only think that this is due to the OPAS not working as it should. One of the rudders is not closing/folding back at higher speed and creating drag, which in turn results in the ski pulling to one side.

    I pulled the steering section and jet pump off to replace the wear ring and found that the filter that sits in the top of the steering assembly for the OPAS system was completely blocked with sand. I have cleaned this filter and will also check the rest of the system including the valve assembly that sits above the jet housing and the side cylinder supports for the OPAS flaps.

    Am I correct in assuming that the OPAS works as following? At high speed the water pressure is forced trough the filter in the steering system up trough the valve assemble and then to each OPAS flap where the water force makes the flaps fold flat against the hull?? I am guessing that due to blockage, the flaps are not folding back as they should and therefore cause problems? I was wondering if i can connect a garden hose to the valve assemble and replicate the water pressure created at hight speed? Not sure what other way I can test the system.


    Cheers


  2. #2
    The ski's have taken a "backseat" to the Corvette DarthAWM's Avatar
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    How does OPAS work? The consensus here is POORLY

  3. #3
    EZ Dock of Long Island Shibby1485's Avatar
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    ur very close...

    on ur ski, yes they work under water pressure... but it's not to tuck them in flat... what they SHOULD be doing is actually raising up and down with water pressure.

    approach ur ski, and take the entire fin assembly and push up on it... u'll note that there is exactly 2" of upward travel in the spring-loaded cylinder.

    so when ur OPAS assembly doesn't get proper water pressure, ur fins are not getting pushed up, or maybe one of them is dragging causing the feeling ur getting.

    the ski turns better with them, WHEN THEY ARE WORKING PROPERLY... my recommendation for you would be to permanantly block the fins in the upward position. this is how the RXP is designed, with a mobilized fin that is always in the upward position with no influence from water pressure.

    this kit does exactly that...

    http://www.4-tecperformance.com/inde...roducts_id=440

    it will immbolize your OPAS rudders to always be locked in the up position and take away that squirelly pulling feeling ur getting to one side or the other

    the same can be accomplished with 3/4" PVC pipe... cut two pieces of 3/4" pipe exactly 2 inches long, and then you put them as spacers on the piston shaft and the rudder wont be able to come down and drag

  4. #4

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    Quote Originally Posted by DarthAWM View Post
    How does OPAS work? The consensus here is POORLY
    You don't speak for me OR many racers.... I wonder who knows more?

  5. #5

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    Quote Originally Posted by Shibby1485 View Post
    ur very close...

    on ur ski, yes they work under water pressure... but it's not to tuck them in flat... what they SHOULD be doing is actually raising up and down with water pressure.

    approach ur ski, and take the entire fin assembly and push up on it... u'll note that there is exactly 2" of upward travel in the spring-loaded cylinder.

    so when ur OPAS assembly doesn't get proper water pressure, ur fins are not getting pushed up, or maybe one of them is dragging causing the feeling ur getting.

    the ski turns better with them, WHEN THEY ARE WORKING PROPERLY... my recommendation for you would be to permanantly block the fins in the upward position. this is how the RXP is designed, with a mobilized fin that is always in the upward position with no influence from water pressure.

    this kit does exactly that...

    http://www.4-tecperformance.com/inde...roducts_id=440

    it will immbolize your OPAS rudders to always be locked in the up position and take away that squirelly pulling feeling ur getting to one side or the other

    the same can be accomplished with 3/4" PVC pipe... cut two pieces of 3/4" pipe exactly 2 inches long, and then you put them as spacers on the piston shaft and the rudder wont be able to come down and drag
    Thanks for your input mate!!

    I am assuming that if I block them in the "up" position they will still function at low speed while steering?

    I also noticed that the controll rods for left to right movement were not the same length for the left and right side, left was a bit longer. I think this would have cuase an issue too.

  6. #6
    jaycee's Avatar
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    Quote Originally Posted by jawz View Post
    You don't speak for me OR many racers.... I wonder who knows more?
    Shots Fired!!!

  7. #7
    H2HO's Avatar
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    Quote Originally Posted by Shibby1485 View Post
    ur very close...

    on ur ski, yes they work under water pressure... but it's not to tuck them in flat... what they SHOULD be doing is actually raising up and down with water pressure.

    approach ur ski, and take the entire fin assembly and push up on it... u'll note that there is exactly 2" of upward travel in the spring-loaded cylinder.

    so when ur OPAS assembly doesn't get proper water pressure, ur fins are not getting pushed up, or maybe one of them is dragging causing the feeling ur getting.

    the ski turns better with them, WHEN THEY ARE WORKING PROPERLY... my recommendation for you would be to permanantly block the fins in the upward position. this is how the RXP is designed, with a mobilized fin that is always in the upward position with no influence from water pressure.

    this kit does exactly that...

    http://www.4-tecperformance.com/inde...roducts_id=440

    it will immbolize your OPAS rudders to always be locked in the up position and take away that squirelly pulling feeling ur getting to one side or the other

    the same can be accomplished with 3/4" PVC pipe... cut two pieces of 3/4" pipe exactly 2 inches long, and then you put them as spacers on the piston shaft and the rudder wont be able to come down and drag
    I notice these kits always indicate RXT. Will it work with RXP's?

  8. #8
    EZ Dock of Long Island Shibby1485's Avatar
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    Quote Originally Posted by jawz View Post
    You don't speak for me OR many racers.... I wonder who knows more?
    i'm in agree-ance... it's all a psychological thing and a fad to tear them off for better tight turning... you want incredible handling you leave them on.... you want to be a top speed queen on calm water and go straight take them off.... no doubt in my mind the ski performs better in the right stuff and carvin up with OPAS still installed... ESPECIALLY on a 3-seater

    Quote Originally Posted by XtRmn8 View Post
    Thanks for your input mate!!

    I am assuming that if I block them in the "up" position they will still function at low speed while steering?

    I also noticed that the controll rods for left to right movement were not the same length for the left and right side, left was a bit longer. I think this would have cuase an issue too.
    yes... side to side alignment will effect it negatively just as up/down motion will. near the steering nozzle there's a black plastic knockle that threads onto that rod... jsut tighten it more to suck that rudder in closer to the hull

    Quote Originally Posted by sstaino View Post
    I notice these kits always indicate RXT. Will it work with RXP's?

    the compeition kit for OPAS? only works on 3-seaters... not the RXP. the 3-seaters have a spring loaded cylinder that moved the OPAS rudder up and down with water pressure. the RXP does not move, it is always permanantly in the up position bc it has a spacer in the cylinder from the factory that keeps it immobilized and in the up position

  9. #9

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    Quote Originally Posted by jaycee View Post
    Shots Fired!!!


    ...........................
    ............................. Did I get him? I'm out of ammo

  10. #10

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    Well I have sorted the OPAS system. Thanks Shibby for your help.

    I did the raise mod to lift the flaps up and keep them there all the time. Also while I had the jet pump out I adjusted the left/right control arms so the OPAS is not better aligned.

    I am in the process of doing a whole bunch of other mechanical things and if I get it all sorted by the weekend, I'll report on any handling improvements.

    Cheers

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