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  1. #1
    home of the dislexic fingers breon's Avatar
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    hull thoughts block offs ride plate sponsons

    posted this in another thread as a response ..just thoughts and would like to here others ideas

    my block offs have fins if you will... that extend past the end of the hull about 1.5 to 2 inches...but they also curve up about 3/8 of an inch as they go past the hull ..as to not scrub speed...never had a porpusing problem ..i made them so they are a little different kinda like an extended ride plate makes you hook up better...butit also slowes you down.. these arnt in the water at speed

    the sponsons are only in the water at take off and in turns...the curve down at the back on the inside the stockers...gives you lift to get up on plane quicker...lower they are the quicker and harder it will turn ..more traction if you will ...

    the new riva ride plate also has a little concave dip just after the intake grate before the cut out at the rear ..for lift...as an experiment it would be interesting to see if filling it solves the porp prob ..would be just a little less lift..it is probably needed because removing the rear of the plate...reduced lift ...it used to create alot of lift sticking down in the water ..consequently drag... my thought is to add a slight curve down at the back edge of the ride plate cut out...like the hull...just like the rear of your hull has a 1 to 2 mm curve down at the very back..sand it out and it will porpus like mad...jerry will tell you .... the front would be held down better by putting the point of lift pivit point more rearward ....it would be like a moving farther back on a sea saw ..more leverage holding the front down...

    this also applies in my business to the length of wheelie bars on fast drag cars...short ones wheelie bars dont have enough leverage to stop the momentom of the front..when they hit it no leverage...it will lift the rear tires off the ground ..and just like us they unhook.... the longer bars have enough leverage to stop it and not lift the rear tires... lift is good get the front tires up 6 to 8 inches ..the car says hooked ...and goes,,,more unhooks and or waist energy ...just thoughts dont know enough about hull design to really go there... but a 1 to 2 mm diff in hull makes huge differences in the way the ski rides

    my feeling is that the block offs come into play like a wheelie bar ..when the bow starts to come up..to high the block off dip and and stop it ...keeping it from getting to much momentem .upward .unhooking coming down and and starting to bounce..

    just my thoughts
    Last edited by breon; 11-21-2009 at 12:01 PM.


  2. #2
    BlackHawk's Avatar
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    Can you take a pic of you block offs?

  3. #3
    KC Blue Thunder's Avatar
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    Quote Originally Posted by breon View Post
    posted this in another thread as a response ..just thoughts and would like to here others ideas

    my block offs have fins if you will... that extend past the end of the hull about 1.5 to 2 inches...but they also curve up about 3/8 of an inch as they go past the hull ..as to not scrub speed...never had a porpusing problem ..i made them so they are a little different kinda like an extended ride plate makes you hook up better...butit also slowes you down.. these arnt in the water at speed

    the sponsons are only in the water at take off and in turns...the curve down at the back on the inside the stockers...gives you lift to get up on plane quicker...lower they are the quicker and harder it will turn ..more traction if you will ...

    the new riva ride plate also has a little concave dip just after the intake grate before the cut out at the rear ..for lift...as an experiment it would be interesting to see if filling it solves the porp prob ..would be just a little less lift..but it may need it because of the reduced lift becsause of the cut out the ride plate ...it used to create alot of lift sticking down in the water ..consequently drag... my thought is to add a slight curve down at the back edge of the ride plate cut out...like the hull...just like the rear of your hull has a 1 to 2 mm curve down at the very back..sand it out and it will porpus like mad...jerry will tell you .... the front would be held down better by putting the point of lift pivit point more rearward ....it would be like a moving farther back on a sea saw ..more leverage holding the front down...this also applies in my business to the length of wheelie bars on fast drag cars...short ones wheelie bars dont have enough leverage to stop the momentom of the front..when they hit it no leverage...it will lift the rear tires off the ground ..and just like us they unhook.... the longer bars have enough leverage to stop it and not lift the rear tires... lift is good get the front tires up 6 to 8 inches ..the car says hooked ...and goes,,,more unhooks and or waist energy ...just thoughts dont know enough about hull design to really go there... but a 1 to 2 mm diff in hull makes huge differences in the way the ski rides

    my feeling is that the block offs come into play like a wheelie bar ..when the bow starts to come up..to high the block off dip and and stop it ...keeping it from getting to much momentem .upward .unhooking coming down and and starting to bounce..

    just my thoughts
    Take off the wedge, your getting to much lift with it. The plate takes the place of the wedge when it comes to lift.

  4. #4
    home of the dislexic fingers breon's Avatar
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    Quote Originally Posted by Blue Thunder View Post
    Take off the wedge, your getting to much lift with it. The plate takes the place of the wedge when it comes to lift.
    thanks ill try it ...i am going to give it a try this weekend and the tweaking starts..my curved runner exhaust manifold spacers should be done the beginning of the week ..so that will also help ...

    it is my understanding that the wedge also makes the water come out of the pump straighter...and gives speed that way as well the sweet spot is not even close to all the way up on the trim ....

    i am pretty sure i am going to need more prop with my new set up as well...psyco rxp has a few we can try before i buy one

  5. #5
    home of the dislexic fingers breon's Avatar
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    Quote Originally Posted by BlackHawk View Post
    Can you take a pic of you block offs?
    i will but cant tonight

  6. #6
    Got Boost? psycho rxp's Avatar
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    Run it first, in all trim settings,see IF u have a bounce, then instead of filling in parts of the plate, shim the rear down some if needed.

  7. #7
    home of the dislexic fingers breon's Avatar
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    i know just thoughts ..i am not willing to f up my new plate ....i dont think i ll bounce at all ....just thought

  8. #8
    jpeconsult's Avatar
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    Quote Originally Posted by breon View Post
    ...it is my understanding that the wedge also makes the water come out of the pump straighter...and gives speed that way as well the sweet spot is not even close to all the way up on the trim ....
    Water runs/flows the fastest when propelled/impelled straight. The more curves, turns and bends in a line/pipe, the slower the water flows. Water doesn't like to turn. The wedge is actually a 2 degree turn, slowing the flow of the pumped water...but lifts the hull out of the water.

    If, what Blue Thunder said is true (and I don't have any reason to doubt), the Riva plate replaces the wedge as taking its place to raise the bow the most possible, then, yes, the wedge would hinder speed. If the wedge assists the plate in lifting MORE hull out of the water, then it would help. I understand both theories COULD work. I'm anxious to know the results.

    I know some prefer a wedge and others do not (not considerring the Riva plate). It may be one of those mods that may provide different results on different boats.

    Back-to-back test it!

    Let us know...I will need the same info. --Jeremy

  9. #9
    Got Boost? psycho rxp's Avatar
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    The RPM gains with the wedge(aprox 150 rpms) comes from spacing the nozzle farther away from the tail cone.

  10. #10
    KC Blue Thunder's Avatar
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    Like I said before My shit bounces like crazy with the Riva open loop plate ( I didnt have this problem before I installed it) Riva recommends the removal of the wedge. If you leave the wedge in the bouncing will be more pronounced. To fix the bouncing you either have to shim the two rear bolts on the plate with I would start 030. shims or install the RE blockoffs. just watch this video of the drags. I lost the race because of the porposing, you can even hear it.

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