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Thread: Prop tunnel

  1. #1
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    Default Prop tunnel

    Looking at buying a an alumacraft with a prop tunnel and running an outboard jet on it. Was wondering what u guys thought about that set up and does anyone have any experience with that set up? Thanks

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    Member AK Troutbum's Avatar
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    If the tunnel is not designed right (for jet application) you won't get good clean flow to your pump. This is my limited understanding of it.

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    I've heard they don't work but it's always the stuff like well my buddy had one or I new a guy that had one that did t like it. It still forces the water to the jet intake but I could be understanding it all wrong.

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    Member AK Troutbum's Avatar
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    Yeah, I think basically it boils down to the quality of water getting to the pump. If the tunnel isn't designed right, the water getting to the pump is full of bubbles/air and will cause cavitation.

  5. #5
    Supporting Member Old John's Avatar
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    Quote Originally Posted by monte007 View Post
    Looking at buying a an alumacraft with a prop tunnel and running an outboard jet on it. Was wondering what u guys thought about that set up and does anyone have any experience with that set up? Thanks
    Gary over at Greatland Welding has "fixed" a few boats with prop tunnels and OB jets mounted... by welding a plate between the Transom and the lip of the Jet...

  6. #6

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    i used to have a lowe with a prop tunnel and a jet on on it worked just fine there was no slide in the cornors i would run the setup agin with no issues did cavitate in small chop but not is bigger stuff nothing that ever was issue there.

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    Member Akgramps's Avatar
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    The only reason the local dealer is selling them that way is because Alumcraft quit making a "jet tunnel" a few years back. There has been some discussion on here if you do a search, both negative and posistive comments were made. I have asked a few folks because I have been curious as well.
    I personally doubt it would work properly but have never been in a boat equiped that way, I guess if it worked well you would see a lot more boats set up that way.......jet tunnel design does vary some but no one builds a jet tunnel that looks like a prop tunnel.

    Sure fire way is to go for a ride in one, are you looking at buying a new boat?
    “Nothing worth doing is easy”
    TR

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    As in boats, one tunnel does not work for all applications. The Alumacraft tunnel is a tall, narrow and long.
    It is more prone to cavitation on corners and is so long it takes away from the planing surface. Tunnel extensions help some.
    Also Specialty Jets make intake fins for the jet foot that funnel more water into the jet.
    Still with all that hassel why not find a boat with a real jet tunnel ? They may not be as cheap, but they work right out of the box.

  9. #9
    Member OzAK's Avatar
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    First hand experience here. I don't own one but one of my best friends has an 1856 (I believe thats accurate as to size) Alumacraft that I have done quite a bit of welding work on. The need for the work will become apparent. He bought the boat from Reeds here in Fairbanks as a turnkey package with a Merc 60/40 factory jet and a prop tunnel. As Madboater said, it is tall, narrow, and long, 72" long for that matter. I have built a couple of jet tunnels in 2 different boat makes, and while there are others around that have done a lot more than that, both were a rousing success for what we were trying to accomplish-make it run shallower by getting the foot up out of the gravel and harms way. So I had occasion to study tunnel design at length before I dove in head first. My buddys prop tunneled Alumacraft is probably the best handling and well done package I have driven in an outboard jet in that it just does everything quite well.

    Enter the need for more power with the growth of his family. Off comes the 60/40 (2 stroke) and on goes the 115 four stroke. The transom needed serious help handling the weight, hence the welding needs. Concerns about the tunnel were raised and then discarded as the boat cared not about the powerplant one bit. On with a windshield and it became the sweetest package ever, bar none the quietest boat I know of and it handles all water well with no cavitation. My 2 bits on what has worked for one guy.

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