Trim Problems

Discussion in 'Boat Repair Help' started by jedamy, Jan 13, 2008.

  1. jedamy

    jedamy New Member

    Messages:
    16
    State:
    mo
    I HAVE AN 88 18FT ALUMA-WELD BOAT WITH A 150HP MERCURY. NO MATTER WHERE I ADJUST THE TRIM TO AT WIDE OPEN THE FRONT OF THE BOAT NOSE DIVES. I THINK IT WOULD GO UNDER IF YOU DONT BACK OUT OF IT
    ANY BODY GOT A CLUE WHY?
     
  2. BKS72

    BKS72 New Member

    Messages:
    3,361
    State:
    East of KC
    Have you checked the trim with it out of the water to make sure the motor is going down as far as it can? Also, not sure how your motor is set up, but if it has the trim-adjustment pin that runs across the mounting brackets, check those and see if it's been moved for some reason. Dunno if you have kids, but if so you know what I mean:wink:

    Have you changed anything lately or shifted anything heavy around? I hate to bring this up, but you don't have a storage compartment or something up front that's gotten full of water while it's been sitting, do you?
     

  3. jedamy

    jedamy New Member

    Messages:
    16
    State:
    mo
    IT DOES HAVE A PIN BUT IT IS IN THE LAST HOLE SO THE MOTOR CAN MOVE ALL THE WAY UP OR DOWN. THE MOTOR IS MOVED ALL THE WAY TO THE BOTTOM HOLES ON THE TRANSOM. I THOUGHT ABOUT MOVING IT UP A NOTCH BUT BY MY THINKIG WHICH ISNT MUCH THAT WOULD MAKE IT WORSE WOULDNT IT? BOAT HAS BEEN THIS WAY SENSE I BOUGHT IT.
     
  4. BKS72

    BKS72 New Member

    Messages:
    3,361
    State:
    East of KC
    Not sure on what moving the motor up would do - trimming all the way down lowers the bow, so moving it up might move the nose up. I've never heard of one going bow-down, usually if they're over powered or something they'll tend to want to fall over on the stern from my (limited) experience. You don't have one of those fins on the motor do you? Dunno if that would do it, but they tell me anything's possible:wink: You might post up in the outboard repair section - not much Bubba doesn't know about boats. Good luck with it!

    Branden
     
  5. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    That is called porpoising. It can be caused by several things, Hook in the hull.motor to low. wrong prop, over powered, weight distribution.
    This is a situation where the bow rises and falls violently. The bow will rise and right before it can lift the stern on pad for easy running it will take a nose dive.
    Now tell me has this boat always done this with you ? I think I read where you just bought it and if so this is why the other guy sold it. It can be cured.
    look at the rod that goes through the transom mount and see if it is set in the first hole next to the transom to let the motor all the way down.
    Let the motor down and look at the antiventlation plate right above the prop and see where it sets in correlation to the keel of the boat. Check you load to see where all the weight is. I know some of those boats came out with a big storage box behind the driver and later they moved them up front. Those are good boats so don't let this scare you off of them. they are tough to beat
     
  6. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    150 on an 18 foot aluminum boat?
    Whats it rated for?
     
  7. GMC FishHauler

    GMC FishHauler New Member

    Messages:
    1,335
    State:
    Waco, Texas, Un
    that does seem like alot of motor for that boat. My bass tracker only has a 70hp merc on it and it is about all i would want on it.
     
  8. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    That boat he has there guys is most likely rated for that 150 or 140. Those are heavy boats and a v hull at that. I have a friend that has a 18 footer and its rated for a 150. But he needs to check is h/p rating for that boat.
     
  9. jedamy

    jedamy New Member

    Messages:
    16
    State:
    mo
    ITS RATED FOR 150 HP ITS AT MY DADS RIGHT NOW SO I WILL HAVE TO WAIT TO WEEKEND TO CHECK FOR SURE WHERE THE ROD IS AT. THEIR IS A BIG STORAGE AND LIVEWELL BEHIND THE SEAT BUT BOTH ARE EMPTY.I DID GET IT LAST YEAR AND IT HAS DONE IT FROM DAY ONE.WILL POST BACK AFTER I GET A CHANCE TO LOOK AT IT. THANKS FOR THE HELP.
     
  10. jedamy

    jedamy New Member

    Messages:
    16
    State:
    mo
    look at the rod that goes through the transom mount and see if it is set in the first hole next to the transom to let the motor all the way down.
    Let the motor down and look at the antiventlation plate right above the prop and see where it sets in correlation to the keel of the boat. Check you load to see where all the weight is. I know some of those boats came out with a big storage box behind the driver and later they moved them up front. Those are good boats so don't let this scare you off of them. they are tough to beat[/quote]
    I FINALLY GOT TO MY DADS TO LOOK AT BOAT THE ROD IS IN THE BOTTOM HOLE I LET THE MOTOR DOWN AND THE PLATE IS ABOUT TO INCHES DEEPER THAN THE BOTTOM OF THE BOAT BUT ABOUT THREE INCHES FOREWARD FROM THE BOTTOM THEIR IS A LONG PLATE ON THE BOTTOM OF THE BOAT IT SETS EVEN WITH THE PLATE ON THE MOTOR. HOPE THAT MAKE SENCE THANKS FOR ANY HELP.
     
  11. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    The bottom plate right above the prop is the one we want to look at. If it is even with the keel then it should be okay. If it doesn't have a whale tail on then that would be the cheapest way to start trying to figure it out. I would look at the load in the boat first and if it has a big load, Like 3 or 4 batteries and fuel tank then I would concertate on moving some of it up front.
     
  12. jedamy

    jedamy New Member

    Messages:
    16
    State:
    mo
    I PUT A WHALE TAIL ON IT AND IT DID NOT SEEM TO MAKE A DIFFERENCE IT DID HELP THE STEERING A LITTLE . IT ONLY HAS A 12 GALLON TANK IN THE BACK AND ONE BATTERY.WHAT EFFECT DO YOU THINK IT WOULD HAVE IF I RASIED THE MOTOR UP ONE HOLE?
     
  13. catfishcrazy256

    catfishcrazy256 New Member

    Messages:
    2,648
    State:
    Indiana
    try raising the motor 1 or 2 holes up on the transom dont get the cavation plate more than 2 ins . obove the bottom of the boat u could try a jack plate i ran a 200 on a 22 ft sea ark with a hydralic jack plate u could trim it all the way out ant throw a 6 or 7 ft rooster tail and it would not porpoise at all FAST TO !:0a26::happy: