DIY jet drive

Discussion in 'Boat Building' started by saqa, Jun 7, 2016.

  1. saqa

    saqa Jonny TooBad

    I have been pondering a small jet drive based on a go-kart type engine to move a very slim efficient light weight hull through the water. Looking for inspiration
  2. t-astragal

    t-astragal Senior Member

    Is it not just a pump? Not sure but guessing that that could be a start.

  3. lite-liner

    lite-liner troll enforcement Staff Member

    salvaged jet-ski from the 80's/90's?
    mine was 425cc & went close to 40mph
  4. HungryJack

    HungryJack Member

    As a general statement,
    Jet drives require more HP than propeller driven craft,
    for the same sized vessel.
    You will also burn more fuel with a jet drive.

    Go cart engine will probably be too small.

    Why you want a jet drive ?
    Unless you need to traverse very shallow water, under 1 foot of depth,
    or you plan to beach the boat frequently,
    a jet drive is not necessary.
    If you have a lot of weeds in the water, it becomes an issue.

    Personally, for tropical fishing, where I might be positioned near
    a reef break ,casting, I like to keep the engine running,
    if I need to pull back quickly because of sea conditions.
    With a jet drive, there is no neutral, when the motor is on,
    you are moving forward.
  5. saqa

    saqa Jonny TooBad

    I have this obsession to build a personal recreational sports cat something like this


    Without the lifting foils initially but featuring the canoe stern that I designed for the larger cat that I am working on, like this

    [​IMG]sil001 by Jonny TooBad, on Flickr

    I am thinking an L shaped rudder stem which will be metal pipe with the rudder blade fitted on the gape of the L and height of transom bottom to hull absolute bottom (the area that would be below the cav plate if a regular outboard was fitted)

    This rudder stem pipe will take input from the pump at the top end and will output via a nozzle at the bottom. And should rotate 360 hopefully with an adapted trolling motor steering mech for maneuverability and reverse functions

    As that rudder blade will tuck behind the skeg area of the hull at any degree of rotation, should be very beachable and non fouling

    I really want to give this the Fiji touch and run a crab claw type sail, nothing powerful, just enough for quite cruising and relaxing occasionally

    I think this setup might be an elegant solution retaining rudders for sailing while having power for regular use
  6. saqa

    saqa Jonny TooBad

    Industrial type high pressure water pumps carry a pressure rating, does anyone know pressure ratings on any jetski output?