vented tunnel

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Thread: vented tunnel

  1. #1
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    vented tunnel

    Is there anyone in the bigbend area that can vent aluminum tunnel hull boats?

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    Senior Member sEA aRKER's Avatar
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    I don't understand what you are asking? I have a SeaArk tunnel hull Bayrunner, you might have to be more specific. Mine is a prop tunnel hull.

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    You can vent the leading edge of the tunnel; usually with a valve to open and close as needed. It breaks the air gap. And allows the boat to run faster in deep water. For example running deep water in the suwannee river dont really need the shallow tunnel so open the vent

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    The guys at East cape skiffs build vented tunnels. Their custom shop could almost certainly do the mod on your boat.

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    Quote Originally Posted by tunlthyme View Post
    You can vent the leading edge of the tunnel; usually with a valve to open and close as needed. It breaks the air gap. And allows the boat to run faster in deep water. For example running deep water in the suwannee river dont really need the shallow tunnel so open the vent
    I thought the vent prevented the suction of the boat to the water, which is what allows the boat to run shallower/faster? I can tell when my 1860 tunnel prop alumacraft unsucks when I go around a wide corner because the boat lifts up a little and starts to slide out more.

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    Senior Member surfman's Avatar
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    Quote Originally Posted by G8trbait View Post
    I thought the vent prevented the suction of the boat to the water, which is what allows the boat to run shallower/faster? I can tell when my 1860 tunnel prop alumacraft unsucks when I go around a wide corner because the boat lifts up a little and starts to slide out more.
    Yea, I would think it is for shallow water. I had one once and once the hull speed got up a little you could feel the boat rise about 2" when the vent started working. Don't know why you wouldn't vent the tunnel. The boat ran sick skinny but sucked in any kind of rough water which is why I got rid of it. That was when I used it in Tampa Bay, now I would love to have it back up in Steinhatchee. They were basically making it illegal to run in shallow water in TB due to the manatee problem they have.
    Tight Lines, Steve
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    Not sure if it makes it go shallower, that would be even better. I'm just looking for more speed on the river and I know it'll do that when vented. I talked to ECC and they said it will help eliminate cavitation and pick up more speed which both I'm looking for. Probably get them to do it; was hoping to get it done closer. Would love to hear some more reports from people that had it done.
    Surfman...when you say it sucked up water didn't you have some kind of drain over the side; or did it end up back in the boat?

  8. #8
    Senior Member surfman's Avatar
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    No it didn’t suck up water, it sucked in rough water. The boat was flat bottom and was a rough ride in rough water. It was meant to run shallow and that was it.

    My vent was just basically a through hull fitting with a piece of tubing that came up through the hull and into the console! I was sure that it would shoot water up but I never saw any water come up in that thing.
    Tight Lines, Steve
    My posts are my opinion only.

  9. #9
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    Unfortunately flat bottom boats aren't going to be great in rough water but if you're running shallow then it normally isnt a problem. 2 to 3ft on noaa isn't too bad inshore with mine but you will have to slow down or lose all your teeth! Also having a hydraulic lift is nice in rough deeper water; it lessons the cavitation.

  10. #10
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    Is there anyone in the bigbend area that can vent aluminum tunnel hull boats?
    Unless you're asking about something much more complicated than it sounds, I don't see why you couldn't handle this yourself. Get a thru-hull fitting (I'd say at least 1") and matching size hole saw, then make the hole, goop it up with some 5200, attach a hose and valve with some hose clamps, and you're done. Should be a 1 - 2 hour task

    You can vent the leading edge of the tunnel
    Don't go with the leading edge, but put the hole just aft of the that where it flattens out. Go just to the right of spot #2 shown in the below picture...



    A boat with a tunnel that is un-vented will create a vacuum, and the suction pressure will pull the back end of the boat down slightly. Installing the vent will relieve the pressure and allow the boat to ride "up" a little more in the rear. Putting the valve in will help you "tune" it, so to speak. The purpose of having the tunnel is to allow the motor height to be raised, thus decreasing the amount it hangs below the boat...which in turn decreases your running draft. Of course, you'd need a jack plate to get that done. At the low point, the cavitation plate on your motor should be level with top of the tunnel. Therefore, the height of the tunnel is effectively how much "draft" reduction your gaining.

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