Results 1 to 5 of 5

Thread: Best way to reduce Jet foot spray back?

  1. #1
    Member
    Join Date
    Apr 2009
    Location
    A-town
    Posts
    153

    Default Best way to reduce Jet foot spray back?

    Been having trouble resolving excessive spray-back from my jet foot. G3 w/ a home built adjustable transom lift. Have lifted the foot as high as I can w/o cavitation becoming a problem, front edge of foot ~1/2" higher than bottom of boat, but still generate too much spray back. Do any of you out there have experience solving this problem with your own boats? have some ideas but would like to see pics. or hear of proven design before buying materials.

  2. #2
    Member
    Join Date
    Sep 2009
    Location
    Anchorage
    Posts
    234

    Default

    I have seen a lot of people putting a flat piece of plastic bolted to the transom or to the top of the tunnel, the part that extends past the back of the boat. Usually the flat plastic piece is bolted to a piece of aluminum and then placed just above the high point of the jet foot. this piece will deflect the water from spraying up any higher than the piece itself. A picture of your boat would help for advice....

  3. #3
    Member
    Join Date
    Mar 2009
    Location
    East-central Alaska
    Posts
    35

    Default

    You have your foot leading edge too high to begin with, it should be just level with or slightly above the boat bottom edge(like no more than 1/4 inch). The test is that with a normal load in a turn the jet doesn't cavitate. How does your boat ride? Bow high, bow low? That would indicate that the motor is not adjusted to the correct angle for the transom. That will cause excess spray. Measure the distance from the transom bottom edge to the foot leading edge, if more than an inch this will cause excess spray.

    To fix the last item, you mount an "L" shaped strip of aluminum the same width of the foot on the bottom edge of the transom with just clearance to not touch the foot when the motor is turned either way. This channels the water breaking away from the transom below the foot line instead of above it, thus deminishing the spray problem.

    Let me know what you do.

  4. #4
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    My Outboard Jet mounting bracket has a piece of UHMW mounted to essentially extend the bottom of the boat over the top of the jet foot leading edge. It works great.

    A friend glued some heavy duty inner tube rubber to the lower area of his transom. He simply lifted the rubber up so that it rode over the top of the jet foot like my UHMW does. That was at least 10-12 years ago and I bet it's still there. It works great, too.

  5. #5
    Member Akgramps's Avatar
    Join Date
    Apr 2008
    Location
    Last civilized place on the planet
    Posts
    2,078

    Default

    Some clarification,
    On the jets I have run the motor seems to run best with the foot tucked in all the wat to the transom, down-forward, whatever you what to call it.
    It also seems to require more than an inch to allow room for the foot to swing w/o touching?
    What I want to know (hopefully somone can explain) is why a boat w/o a tunnel seems to produce a nice "flat apron" of clean water coming off the back of the boat hull and feeding to the jet. Hence, many flat bottom w/o UHMW, rubber or whatever.
    Tunnel hulls on the other hand seem to require a flap to control spray, do you suppose it is because the tunnel creates so much more turbulence? Is it that obvious? did I answer my own question???????



    Quote Originally Posted by floatplanepilot View Post
    You have your foot leading edge too high to begin with, it should be just level with or slightly above the boat bottom edge(like no more than 1/4 inch). The test is that with a normal load in a turn the jet doesn't cavitate. How does your boat ride? Bow high, bow low? That would indicate that the motor is not adjusted to the correct angle for the transom. That will cause excess spray. Measure the distance from the transom bottom edge to the foot leading edge, if more than an inch this will cause excess spray.

    To fix the last item, you mount an "L" shaped strip of aluminum the same width of the foot on the bottom edge of the transom with just clearance to not touch the foot when the motor is turned either way. This channels the water breaking away from the transom below the foot line instead of above it, thus deminishing the spray problem.

    Let me know what you do.
    “Nothing worth doing is easy”
    TR

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •