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What Is Porposing????

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Old 05-31-2011, 01:49 PM
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Here is the link to info on my boat
http://vtesinla.org/Lightning2010/models.asp?id=27st
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Old 05-31-2011, 03:11 PM
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Is it a splash of an Eliminator hull? Or an previous Eliminator hull/mold/model?
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Old 05-31-2011, 03:45 PM
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I think what's happening is typical of that tyPe of cat. I have owned several and my 25 warlock did the same. Basically ended at high 70's on glass. With a little chop it wouldn't because you are gettnf the hull out of the water consitently. A better prop can help in provided better lift. At 70 things fun start happening and now it's time to tune (; small tabs can help but is just a band aid. What you are describing is pretty normal with a tunnel hull.
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Old 05-31-2011, 04:43 PM
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Quote:
Originally Posted by Sydwayz View Post
Is it a splash of an Eliminator hull? Or an previous Eliminator hull/mold/model?
Not really sure what the story is on the hull just someone that use to work at Eliminator told me it was or like an Eliminator hull

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Originally Posted by Poker~N~Run View Post
I think what's happening is typical of that tyPe of cat. I have owned several and my 25 warlock did the same. Basically ended at high 70's on glass. With a little chop it wouldn't because you are gettnf the hull out of the water consitently. A better prop can help in provided better lift. At 70 things fun start happening and now it's time to tune (; small tabs can help but is just a band aid. What you are describing is pretty normal with a tunnel hull.
Ok, so the main thing I need is more power for more speed then it will go away? Or stay away from glassy water My speed seemed a little low so does this slow you down?
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Old 05-31-2011, 04:56 PM
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Its when your boat screws the water
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Old 05-31-2011, 05:00 PM
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It sounds like you are right at the point between becoming a true cat and just a twin hulled boat. What is supposed to happen on a cat is you pack enough air into the tunnel and it lifts the weight of the boat off the sponsons and floats the boat on an air cushion. This allows cats to reach high speeds on less power and ride smoother in some conditions than a v-hull. But you have to be going fast enough for the air to build in the tunnel and create positive lift. For many cats that speed is at 70-80 mph. As you near the speed where you pack air you can experience the porpoising you describe because the hull is starting to lift on the air, but as it does some air dumps out the back of the tunnel and you lose lift, so it drops. Then the pressure starts to build back up. And on and on.... In the past some makers added a tunnel tab which allowed the operator to tab down some and close off the back of the tunnel, this would allow more lift at lower speeds and stops or diminishes porpoise. Of course it can also cause the boat to blow over or do other nasty things if not retracted at high speeds. You could also add a small, fixed tunnel tab which may get you past the porpoise, or you are going to need enough power to drive through it (of course once you really pack air.....YEE HAW).
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Old 05-31-2011, 05:31 PM
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Quote:
Originally Posted by Ted G View Post
It sounds like you are right at the point between becoming a true cat and just a twin hulled boat. What is supposed to happen on a cat is you pack enough air into the tunnel and it lifts the weight of the boat off the sponsons and floats the boat on an air cushion. This allows cats to reach high speeds on less power and ride smoother in some conditions than a v-hull. But you have to be going fast enough for the air to build in the tunnel and create positive lift. For many cats that speed is at 70-80 mph. As you near the speed where you pack air you can experience the porpoising you describe because the hull is starting to lift on the air, but as it does some air dumps out the back of the tunnel and you lose lift, so it drops. Then the pressure starts to build back up. And on and on.... In the past some makers added a tunnel tab which allowed the operator to tab down some and close off the back of the tunnel, this would allow more lift at lower speeds and stops or diminishes porpoise. Of
course it can also cause the boat to blow over or do other nasty things if not retracted at high speeds. You could also add a small, fixed tunnel tab which may get you past the porpoise, or you are going to need enough power to drive through it (of course once you really pack air.....YEE HAW).
LOL, thanks for all the great info
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