Trim tab

Discussion in 'Bubba's Outboards' started by Vulture, Apr 20, 2007.

  1. Vulture

    Vulture New Member

    Messages:
    78
    State:
    CA/AZ
    How important is the trim tab? I have a 1994 20 Hp Merc that I bought used. Strong running motor with no problems other than the trim tab is missing. Should I buy one and if so at what degree do I set the tab?
    I use the motor in freah water only.
     
  2. crusinman2002

    crusinman2002 New Member

    Messages:
    374
    State:
    Mukwonago, Wisconsin
    it all depends on if u want to plane the boat out... the trim tabs will help in planing out which will increase your fuel mileage... other than that they will help keep the bow down a bit when the water starts to get a bit rough... its hard to tell if u need them or not, what style boat is it? i imagine its a jon boat, are they mounted to the boat or the motor?, i imagine to the boat, and did they come factory or not? how much would it cost to replace the one?

    someone on here will have a better answer as far as if you need them or not. this is just my 2 cents
     

  3. jtrew

    jtrew New Member

    Messages:
    4,404
    State:
    Little Rock, AR
    As far as I know, the trim tab serves two important purposes. Proper adjustment of the tab will eliminate any tendency of the boat (motor) to pull to one side or the other. For example, on my 25hp 4-cycle Yamaha, with the original prop installed, the trim tab was set straight back in a neutral position. I changed the prop to a 4 bladed composite prop, and now there's a strong pull to the left; adjusting the trim tab to the right will correct this.
    In some waters, there can be a galvanic reaction between different metals, resulting in one of the metals being eaten away; looks kind of like rust, but it isn't. Obviously, you don't want an important part of your motor eaten away, so the trim tab is made of a sacrificial metal, usually zinc, so that if this reaction occurs, it will be the relatively inexpensive, easily replaceable trim tab that gets eaten away.
    This galvanic reaction is more likely to take place in salt water or contaminated water, so if you only have your boat in pristine waters, you're probably pretty safe without the trim tab, but why take the chance? Since trim tabs are much more likely to be eaten away than accidentally lost, the fact that yours is missing leads me to believe that it's probably pretty important that you replace it ASAP.
     
  4. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    I don't know why it's called a trim tab. it serves no purpose in trimming, it does, however, serve a purpose in restricting torque tension against your arm and tiring you out on long runs. That's it, it should be called a torque tab.:lol:

    And like Jerry says, it acts as an anode to prevent electolosys created corrosion in some waters.

    I had a 20 hp merc with it missing also, I had no trouble other than the arm tiring issue.
     
  5. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    As far as setting it, as you look at the engine from the rear, set it to the far right position to counter act the torque.
     
  6. crusinman2002

    crusinman2002 New Member

    Messages:
    374
    State:
    Mukwonago, Wisconsin
    oh... thanks bobpaul... i thought he was talk bout the trim tabs like what you mount on a small boat for planing out.
     
  7. jtrew

    jtrew New Member

    Messages:
    4,404
    State:
    Little Rock, AR
    Those are trim tabs too, but they're on the boat, I was talking about the trim tab on the outboard.
     
  8. Vulture

    Vulture New Member

    Messages:
    78
    State:
    CA/AZ
    Thanks everyone for you helpful suggestions. I ordered one to prevent tiring. When you run big lakes or big rivers you don't need a tired arm. Especially if I hook up a big flattie. I need all the strength I can get.
    I'll set as far right as I can and take it from there.
    Again Thanks to all.