Too much boat for the motor?

Discussion in 'Boat Repair Help' started by dixiedrifter, May 28, 2006.

  1. dixiedrifter

    dixiedrifter New Member

    Messages:
    102
    State:
    Tennessee
    Since I re-did my old boat it has added a lot of weight to it and it is now having trouble getting up on plane and basically running like a slug. It is a 16' flat bottom bass tracker hull with a '69 25hp Johnson.

    I'm thinking of adding a small hydrofoil to it and see if that will help me out some. Ultimately I'm thinking I need a bigger motor.

    Any words of wisdom?
     
  2. samh

    samh New Member

    Messages:
    807
    State:
    Damascus,Arkansas
    Weight makes a huge difference in a boat, I've got an old
    '84 model Champion bass boat, 17 feet long with an '84-150 Merc on it, with the gas tank 1/2 full and only me in it it'll run in the low 60's, fill the tank (only holds 18 gal.) and add another person and it does good to hit 50.
    Whale tail type foil helps, you might also try a smaller prop. If I'm fish'n alone I run a 25 pitch, if I've got company I drop down to my 21, makes a big difference in the whole shot.
     

  3. Iowa_Josh

    Iowa_Josh New Member

    Messages:
    1,463
    State:
    Central Iowa
    Sam is probably right, if you were propped for running empty you don't have the right one anymore.
     
  4. shortshank

    shortshank New Member

    Messages:
    389
    State:
    Oregon
    I'd trade that 25 in for a larger model. Keeping in mind the additional weight of my new motor too. If you can't get your price for your motor, they don't eat anything, and you might come across another boat you could up-grade with it. I have an old..old Buccaneer 25 horse that has been with me for 15 years. It has filled in on more than one occasion. It just keeps on going, and I'm glad to have it for a spare. Before I spent any more money on that motor I'd buy a larger one. No matter how you modify it, you still have a 25 horse motor if you don't trade/sell it.
    Don
     
  5. badkarma

    badkarma New Member

    Messages:
    772
    State:
    Oxford,Miss
    A large boat with a small motor means you travel slow.I have an old very heavy 1969 14ft simi v that I ran all over the local lakes and rivers for years with just a 5hp to push it.Heck I even ran miles out in the Gulf in that thing.Slow yes and it took a while but it did get me back to the boat ramp.
     
  6. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    If the boat was fine before the rebuild and now it is not, I would be questioning what I did to the boat.
    Even if you did put a bigger motor on the boat to overcome the weight, the weight is still there along with probally not the proper trim.
    In other words. A larger motor may intensify the added weight in the form of dangerous to operate.
    Its not hard to take a seaworthy hull and make it suceptible to broaching or capsizing. It also doesnt take much to raise the center of gravity on a hull either.
     
  7. dixiedrifter

    dixiedrifter New Member

    Messages:
    102
    State:
    Tennessee
    A sheet of plywood in the bottom, two heavy batteries makes a big diffrence in weight in a 16 foot boat. Its almost like adding another person.

    Anyways I went to B*** Pro Shops and bought a bolt on hydrofoil for $30. I'm going to put it on this afternoon and see what happens.

    Two more questions about the trim and props...

    My boat trim setting is currently sitting on the fartherest hole back... keep in mind my transom is angles slightly so the foot is about a 90 degree angle with the bottom of my hull. Its kinda hard to explain what my boat does... when I have two ppl in the back the bow likes to rise up and it takes it a bit longer to get on plane than when I'm by myself. When I have a person up towards the front, it gets up on plane quicker but it runs slower. When I have 3 ppl in my boat it doesn't really get up on plane worth a darn and it kinda chugs along. How do I need to adjust the trim?

    Also I do have a spare prop. I do not know the pitches on the props, but the one I have on it now it appears a slightly more agressive pitch. Should I try putting the other one on and see if it makes any diffrence?
     
  8. YeeHaw

    YeeHaw New Member

    Messages:
    446
    State:
    Quincy Illinois
    Git-R-Done, that's all I have to say.
     
  9. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Sounds like you have changed your boats entire characteristics... which means the data plate is no longer valid. You need to add the weight of the material you put on your boat and subtract it from your maximum weight capacity...you can put yourself in the position where you could have the boat and motor, but insufficient weight to allow a person in the boat to run the motor. LOL. If you have added substancial weight, then you have also compounded the problem because a bigger motor would mean more weight and you'll possibly exceed your boats capacity. You need to look at your upgrades and ask yourself if they were really necessary. If not, take them out and restore the boat to what it was. Nice to have things are just that...nice to have. Your life is probably something you find nice to have also.
     
  10. dixiedrifter

    dixiedrifter New Member

    Messages:
    102
    State:
    Tennessee
    I honestly think the boat is fine weight wise and is well within capacity. When I get my ISP up and running again at the house I'll take some pics of it sitting in the water and ya'll can judge for yourselves.

    But as was said before, adding all the stuff changes the boats characteristics. I went to the dealership today and asked them about which props to use. They said to compare the original RPMs the motor was designed to run at WOT with what it is doing now. If the RPMs are lower then what they are supposed to be, then the prop has too aggressive a pitch and should be dropped down a degree or two.

    I got to looking at it last night and the prop that is on it is stamped MICHIGAN and I'm thinking its aftermarket. The other two props I found out in the barn are Johnson numbered 9x9 and 9x10... I plan on crossing them tonight and seeing what pitch they are.