jet drive for small river fishing

Discussion in 'Propulsion' started by kenstl17, Dec 21, 2004.

  1. kenstl17
    Joined: Dec 2004
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    Location: MO USA

    kenstl17 New Member

    I am looking for a small river boat, 14-16 ft welded jon style, that has an inboard jet. Most on the market are larger/longer boats and the smaller boats, use outboard jet drives.

    Has anyone built a jet drive fishing boat with the use of a motor from a
    sea-doo or jet ski motor?


    Has anyone taken an older mercury sport jet 90-125 (made from 92-95), and customized a welded jon or modified v?

  2. Enough of a deep V is the problem in that size boat- unless you can afford $ 7-10,000 for a used jet sprint boat. They are not called VACUMS for nothing.
  3. CVM

    CVM Guest


    Have a look at the jet boat web sites in New Zealand,( true river boating was pioneered here. I have a 15' Hamilton ( hull with a 302 ford driving a 3 stage 773 Hamilton pump, it will go anywhere you have 2" of water or more, can pay anything from a few thousand to fifty thousand for a boat. Don't waste your time with PWC jet drives as they are far to small to push a 15' boat. Mercury Sport jets are gaining favor as they are light and easier to push off the rocks than a boat like mine. Anything around a 16deg dead-rise at the transom gives good shallow water capabilities but may pound a little in big water.
    I did some boating in a little Hamilton 131 (14') with a 120 sport jet a few years back and it went great, only needed half a bucket of water to get up and going and could plane on a wet rock, I asume a 90 would be great also.
    Rip into it you'll love it.
  4. Only needed a half bucket-- is that a hand prime or a joke?
  5. CVM

    CVM Guest

    Half a bucket

    Just a joke Richard.
    Need about 8" - 12" to get going but will sustain plaining in 2"-4" depending on how many pies you have been eating.

  6. Are the jets still unhappy in a dock with muck 12" to 18" below?
  7. CVM

    CVM Guest


    If I understand you correctly the muck you speak of would get stirred up but won’t cause a problem. We run sand traps which catch all the particles which would normally settle out in engine water galleries and are difficult to flush out.
    The water jet isn’t well understood there are a lot of misconceptions even by experienced boaters and boat builders.
    Weed is the biggest problem as it is with props, heavy weed can and will block an intake but generally once you shut down it self clears. On the odd occasion when you cant get a clear spot to start off in then that’s a problem and I have experienced this once and I have owned a Jet boat for 20 years and that was because the lead boat chickened out and slowed down, if we stayed on the plane we should have been O.K. Maybe. Remember when your on the plane the intake only draws water from 1" below the hull.
    One thing to consider is that due to the braded nature of our rivers in “Gods Own” intake screens will run ¼” wide bars with a ½” gap between them to reduce the size of shingle going through the impellor’s. All the sport jet systems I have been involved with here have had aftermarket screens with the aforementioned geometry, performance isn’t noticeably affected if at all.

  8. I never power in weeds. Rock or logs kills bottoms on any boat. Thanks, Rich
  9. CVM

    CVM Guest

    I don’t think we are comparing apples here, the keel plate on my current boat is ½” and the side bottoms and front panels are around ¼” thick, it takes a severe hit to tear ¼” 6061 T6 Aluminum in a 15’ boat. Never had a problem with logs but certainly put a few dents in on rocks, anything sized like a football at 30mph will give you a hurry up but no hole. Most blokes would agree there is no fun in riding a bike around a car park, you have to get into it and give it a go.
  10. Now I know how " Flat Rock Weed Bed " got it's name. :) Cheers.
  11. TJP
    Joined: Nov 2006
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    Location: Rosebery

    TJP New Member

    Hamilton Jet Drive

    Not sure if this will find you as it is an old thread.

    I use a Hamilton J52 with a Ford 302 Cleveland and two stage 750 jet unit for waterskiing. I am looking to get more pull out of the water. The engine pulls 4000 rpm at WOT and does about 42 knots. What is my best option. I like jet drives for their versatility but would just want a little more shove for skiiing.

    Would appreciate a reply.

  12. akscott
    Joined: Jan 2007
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    Location: Anchorage, AK

    akscott New Member

    jet boat w/ pwc engine

    I have a modified Weldcraft 12' boat that I put a Seadoo 720cc motor and an old berkeley 6JA jet in. It's seriously well made welded aluminum boat
    but still pretty light.

    It's a blast to run, runs very very shallow, and tops out at approx 25-28mph.
    With a passenger and extra gear it feels overworked, and performance definitely drops. (The old 6JA jet is likely holding me back; was told they were designed for 35-75hp motors)

    I have had that boat in places I doubt very few jet boats could go. I have pushed it over gravel/sand bars by myself and kept on going.

    If I had it to do over, I may have looked into trying to fit a merc sportjet 2.3L in there with a different jet unit. Would probably get 35-40 mph out of it and alot more power out of the hole. Would make it a fun little ski boat as well.
  13. stonebreaker
    Joined: May 2006
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    Location: Shiloh, IL

    stonebreaker Senior Member

  14. ghostjet
    Joined: Oct 2007
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    Location: montana

    ghostjet New Member

    im building 16 ft welded aluminium jet boats that are fast lite and go in very little water. if you would like some pics and more info you can reach me at

  15. ghostjet
    Joined: Oct 2007
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    Location: montana

    ghostjet New Member

    new email is these boats that i build are 63 hp and run 34 mph on a 16 ft welded aluminium hull.
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