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Thread: Anyone ever built a tunnel jet?

  1. #1
    Member Yukoner's Avatar
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    Default Anyone ever built a tunnel jet?

    Looking on-line, there are some sources for welded Aluminum hulled jetboat plans, but none utilizing the tunnel design for OBJ's. Anyone ever built there own? Where did you get plans, or did you just design it yourself?
    I'm looking at building one, and failing finding some tunnel plans, might just work with my brother in law who is a marine architect.
    Cheers all
    Paul

  2. #2
    Member AK NIMROD's Avatar
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    here are a couple links...not exactly what our looking for but this guy had written other articles about tunnels jet boats i could not find those yet. you might be able to do a search and find some of the other ones. were also articles about putting "plastic" bottom on tunnel design. i have copies saved somewhere but they may be up at work. when i locate them i will let you know.
    a friend of mine replaced bottom of 14 foot lowe big jon and designed a tunnel in it. it worked real well. i will see if i can contact him and get him to pm you.

    http://www.wincoscustomlures.com/hotnews/aug07_hotnews/7_steps.pdf

    http://www.fish.state.pa.us/anglerboater/1999/sepoct99/jetboard.htm
    hope this helps
    RETIRED U.S.A.F. CAPT.; LIFETIME MEMBER NRA; LIFETIME MEMBER ALASKA BOWHUNTER ASSOC.
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    I have watched a tunnel built into an older G3 about 6 months ago, but couldnt tell you how he did it. It was a guy I work with and he had a good friend of his, who was a marine welder, design it and assist him with the install. Judging by what I saw, I would reccomend going with your brother-in-law and ask him design it. It looked fairly involved and with the wrong design could seriously jack up a good boat.

  4. #4
    Member Yukoner's Avatar
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    Thanks for the link.
    Outlaw Eagle has some good design info for OBJ tunnels as well. Design parameters seem to be pretty straight forward with regards to width, heighth and length forward of the transom.
    What have they been replacing the SportJon hulls with, 5 or 6000 series Al?

  5. #5

    Default Tunnel Jet

    I have a Tunnel Jet at my cabin on Flathorn Lake. Its about 10 years old . Bought it new. Have the dreaded CRS disease. It is either an 18' or 20'. Can't remember the brand. Towed it out to Flathorn behind a snow machine and had it loaded with metal roofing and propane. Made a great sled. We ran it with a 50 hp Johnson jet a couple of seasons. Fishing 4 people on the Big Su. A little more power would be better. Have no complaints with it. you lose a little buoyancy with the tunnel, but it does protect the jet .Pretty much looks like a large Jon boat with the tunnel added. Pretty light weight.

  6. #6
    Member Yukoner's Avatar
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    CRS disease, you have me there. Cavitation issues? Out of curiosity, do you recall if the front lip of the tunnel is at 90deg. to the hull, or is it sloped up?

  7. #7

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    haven't had any cavitation issues. It is sloped up towards the bow.

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    Default jet tunnel

    I installed a jet tunnel in a 14' Lowe. I went 2.5 times the length of the jet intake and 1.75 times the width of the jet for the tunnel dimensions. The tunnel was 3'' deep at the transom leading. I also replaced the bottom of the boat with aluminum 1/8" sheeting. I experienced great results with no cavitation. If you would like to discuss, leave me your phone number and I'll give you a call.
    Mike

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