mo power

Discussion in 'Bubba's Outboards' started by bigmaac73, Mar 12, 2008.

  1. bigmaac73

    bigmaac73 Member

    Messages:
    434
    State:
    Lenoir City, TN
    I recently bought an 06 merc mariner 9.9 and put in on my little river runner. The boat is a 14 ft semi V jon boat. After running it a few times it just seems like the motor is not running at its full potential. Is there anything that I can do to make more power? Any mods that I can do that will up the preformance? I guess it just got to me when I saw an old johnson 5hp motor on a flatbotom jonboat screaming up the river(you know the pride factor-my engine is twice the hp but that one was going alot faster). Anything???????
     
  2. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Get a jon boat and you will probably run rings around him. The jon boat does not set deep in the water and skims across the top. The v bottom sets in the water and your pushing water with the motor also. Can't compare apples with oranges as they are different. Course your other option is to get a bigger motor. LOL
     

  3. baitchunker

    baitchunker New Member

    Messages:
    1,689
    State:
    alabama
    back when i had a 15 johnson, i put one of those whale tales on it. it made all the difference in the world. it would plain faster, run faster, and conserve gas, plus it was cheap.
     
  4. bigmaac73

    bigmaac73 Member

    Messages:
    434
    State:
    Lenoir City, TN
    Well first off I do have a flat bottom boat. It is a Semi-v because it has a flatbottom and a v front. The only difference is that the other boat had a square front and mine was a V front. I thought the V's would actually cut the water better. I have looked at those whale tales, I didn't know that they actually made that much of a difference.
     
  5. Wabash River Bear

    Wabash River Bear New Member

    Messages:
    3,019
    State:
    Indiana
    What you are describing is a modified-V. Most modified-v's are not true flat bottoms. They are usually 3 to 5 degree bottoms. If you are sure your motor is running properly, a whale tail (stabilizer) will help a bit by getting you on plane quicker and keeping the prop from cavitating as easily. Prop choice could be a factor on why your 9.9 got spanked by a 5. You'll need to find out what rpm your 9.9 is specked to run at, and check it with a tach on the water. That will tell you if you need to prop up or down, or if your about right. Good luck.
     
  6. WTL

    WTL New Member

    Messages:
    11
    State:
    alabama
    Outboards arent really like working with automobile engines - with a automobile engine you can pick up 5 hp here, 10 there....maybe 15 if you do something big like longtube headers with a good intake or roller rockers...

    Outboards, as I understand it, pretty much have a restrictive exhaust - and there aint much you can really do about it. Some people have tinkered with their carbs, but on a 9.9 motor how much can you really gain doing that? Maybe put you over 10 hp? If so was that really worth it?

    Probably the best things you need to look at are boat balance...how it planes, engine height - location of the cavitation plate in regards to the hull, and the pitch of the prop. All that is trial and error stuff, but it will make the most difference.
     
  7. cantstopgrandma

    cantstopgrandma New Member

    Messages:
    955
    State:
    MD
    Maybe its not actually a 5hp.....just a 5hp cowl. My uncle tells the story of when he was a kid, they had a 6hp bored out to fit a 10hp piston. I dont know about other states, but Maryland makes you buy the registration stickers if you go over a 7.5 horse motor on your boat ($24 biannually), but they give you the stickers free if you stay at a 7.5 or less. If someone has done like my uncle did as a kid, they could potentially cheat the system. I've also noticed that boat shape and size has a lot to do with speed. A wider boat usually doesnt' draft as much water (displaces the weight over a wider surface area), and therefore sometimes goes faster with the same size motor. A modified-v or semi-v, will probably be slower than a flatbottom because the flatbottom rides up on top of the water, and the semi and modified-v hull has to push thru it, which is why a flatbottom planes easier. We put an 8hp on my dad's semi-v 12' boat, and when we put the same motor on my 14'x48" flatbottom jon, my boat did about the same speed as per GPS. Both are aluminum boats,with mine being over a foot wider and it weighs more. Which brings me to another point....weight. Obviously you could take 2 identical boats with identical engines and put more weight in one, and the lighter one is going to go faster. Could you have more weight in your boat than the guy with the little motor?