Need more power...

Discussion in 'Boat Tips' started by Mr.T, Apr 12, 2006.

  1. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    Well, after about 10 hours in my new boat, I've come to the conclusion that a 60hp 4-stroke isn't enough power for me -- I find myself running around at nearly wide-open throttle all the time, and that can't be good on the engine. If I drop the power back to 4500 rpm or so, the boat barely stays on plane. Didn't really have any option to upgrade the engine when I purchased, as the boat was "clearance" priced and the dealer just wanted it gone.

    So I'm thinking of trading up for a bigger engine -- want to stay with a 4-stroke, but not sure whether to go to a 90hp or jump on up to 115hp. I'm hoping the dealer will trade for my nearly-new engine and give me a reasonably good deal but I'm sure I'll still end up taking a bit of a loss on it.

    So my question is:

    How much performance increase should I expect if I move from 60hp to 90hp? Enough that I won't have to run around at full trottle all the time just to travel at a reasonable speed? If it's only $1000 or so difference between 90 and 115hp, should I just go for the bigger engine, or is 90 more than enough?
     
  2. sgt_rob

    sgt_rob Member

    Messages:
    961
    State:
    Bossier City, LA
    Why not keep the 60 and get a whale tail or other type of planing device. A new motor is going to be expensive! What size/type of boat is the 60 on? What is the max HP rating for the boat?
     

  3. three_rivers

    three_rivers New Member

    Messages:
    688
    State:
    Tupelo Ar
    I agree with sgt rob on that accessment. If your not looking for any more speed and just being able to stay on plane a whale tail should do the trick. As inexpensive as one is compared to more power that would be the first route i'd try before taking a loss. Now if you decide to go with a bigger motor i've got an 17ft express with a hyperlift hull and it has a 90hp merc two stroke. A 90 was what the boat was rated for. The last boat we had was underpowered so underpowered in fact that with three people we couldn't plane. I wanted a boat with enough power to get me out of sticky situations fast and easily run with what and who ever i had in the boat. I figured it would save in the long run without all that undue stress on the engine trying to plane and burn less fuel too. With that 90 on my boat at wide open when the waters smooth the boat feels like its literally floating on air. The fastest it has got was 57 up on one of the local lakes but 90% of the time its usual speed is around 30. Any faster on the water is dangerous.....
     
  4. BAM

    BAM New Member

    Messages:
    827
    State:
    Tennessee
    What was the rpm at wide open throttle?
     
  5. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    T you have received some good advice.Check the max horsepower rating for the boat.Should be on the data plate.What RPM are you running at WOT?Check your owners manual to see what the optimium range is.If you are significantly below or above the recommendation a new prop may be in order.A whale tail will help but if you remember rule number one about boats."The boat you have is exactly 2 ft to short" then rule number two should be "The motor you have is smaller than the one you really wanted".You don't say what type ,lenght or weight your present boat is so its hard to give you accurate data.Start with the above then come back if you need additional help/recommendations.:)
     
  6. Nobody Special

    Nobody Special New Member

    Messages:
    614
    State:
    TN
    You might just have the wrong prop on the motor. But if the boat is rated for up to 115 hp, then you probably don't have enough motor.
     
  7. jtrew

    jtrew New Member

    Messages:
    4,404
    State:
    Little Rock, AR
    Before you go to the expense of a new motor, you might want to check into putting trim tabs on your boat.

    "Whether they're hydraulic or electric, trim tabs are among the more useful accessories you can have on a boat. They help get the boat on plane, allow it to stay on plane at lower speeds, let you "balance" the craft by adjusting for weight shifts and improve a boat's riding qualities in various sea conditions. And, when used in conjunction with trim, the proper use of tabs can enhance top speed in a high-performance hull. "
     
  8. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    Thanks for the replies -- the boat is an Xpress HD18SC (basically an aluminum bass boat). I'm sure the prop match is as good as I can make it; this boat is just too heavy for a 4-stroke 60hp engine. It might have done better with a 2-stroke 60 or 75, but not a 4-stroke 60.

    Runs between 5500 and 6000 rpm at WOT, going around 32 mph. Drop to 4000 rpm and it won't stay on plane.

    Talked to a couple of dealers this morning, and learned that adding a "whale tail" to your engine will VOID the warranty on the lower unit. So think twice before going that route.

    I've found an '05 115 hp 4-stroke that I can trade for about $4000 difference - it's a lot of money and my wife is going to kill me, but I think I'll be happier in the long run. It's a bit of a logistical nightmare dealing with the bank and trying to get a lein release on the motor only, but I think it can be done.
     
  9. catseeman

    catseeman New Member

    Messages:
    1,189
    State:
    Indianapolis, Indiana
    did the tilt trim set correct. theboat maynot be positioned righ o spee.
     
  10. FishMan

    FishMan New Member

    Messages:
    2,293
    State:
    Tennessee
    get the bigest you boat is rated for, if 60 is not happy then 90 will not be happy. bigger motor less work less fuel = less cost in the long run and better trade in value.
     
  11. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    Think that's just what I'm going to do.

    Found another dealer who will give me a 2006 model 115 hp 4-stroke Yamaha, install it and give me a stainless prop, all for $4000 difference -- $2500 better than the next closest dealer. Got the sales order already in hand, so it's a done deal.

    Think I'll be a lot happier - especially if I venture out onto the Missouri River with this boat, think it'll feel a lot safer.
     
  12. three_rivers

    three_rivers New Member

    Messages:
    688
    State:
    Tupelo Ar
    One other thing you might want to keep in mind. That four stroke is heavier than 2 strokes. I have seen boats with four strokes develop cracks in the transom just because of the added weight.
     
  13. Coloman

    Coloman New Member

    Messages:
    441
    State:
    Soddy Daisy, Tn
    What is the maximum that your boat is rated for. If it is a 90 HP., I would not go above that.
     
  14. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    The boat is rated for 115, so that's no problem. But thanks for the reminder. Though I can't imagine why someone would put a bigger engine on a boat than it's designed for, but I guess some folks are smarter than the engineers at the boat company...

    And the 4-stroke Yamaha 115hp engine weighs 46 lbs more than it's 2-stroke brother (402 lbs vs 358 lbs) - so I don't anticipate any problems with the transom cracking. I'm not sure the argument about 4-strokes being so much heavier than 2-strokes is really valid. At least not in this horsepower range -- maybe at 250hp there's a bigger difference weight. (I wanted to check the difference between Yamaha's big engines but their web site crashed as I was trying to find the information...)

    Now I just have to wait for the state to mail my title (12 weeks after buying the boat...) and I'll be ready to make the swap.