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  1. #1
    Lieutenant Commander bowman316's Avatar
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    Default What size motor for 12 ft V-hull Aluminum boat?

    I have a 12 ft Simple Aluminum slight V-Hull boat, and want to use this boat to run up river, this river can get quite a current when water is running. So what size engine would have enough power to get up a fast current? I was looking for a 9.9 hp, but I wonder if a 6 would be able to do the job?

    the boat is very light, maybe 200 lbs. And the beam is about 3-4 ft wide. closer to 4 ft wide.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  2. #2
    Lieutenant Mark_VTfisherman's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Not knowing the size of the river and what the current is, I can't say for sure, but most 12' boats do fine with a 6-or-so.

    But if your boat is rated for it, I would go with the 9.9. A small aluminum will really scoot with a 9.9, and save you a lot of fishing time
    Clean feet are happy feet; same for boats.
    1964 MFG Niagara Deluxe

  3. #3
    Lieutenant Commander bowman316's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    This is the Susquehanna river, at the Head of the Chesapeake bay. It is about a mile wide, But there is a dam upriver, and when they release water, it may be a 5 MPH current, maybe more.

    I had a 2 50 lb thrust trolling motor's on there, and had both going and was just staying still in the current.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  4. #4
    Lieutenant Commander jasper60103's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    '77 Crestliner Voyager Deluxe 16' (semi V), Spartan WondeRoll tilt trailer, '81 Johnson 25 hp, '88 Johnson 30 hp, '87 Evinrude 30 hp

  5. #5
    Lieutenant Mark_VTfisherman's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    9.9, definitely.

    For trolling motors you can guess at about 1hp for every 25- 35 "pounds of thrust."

    It's actually not that simple, and I think there is a thread somewhere about the math, but that is good enough for easy figuring.

    So a 6hp will just barely creep you over the speed of the current. It may not plane your boat well, either, but I have no reason to say that other than a guess. You will likely plane out about 10 to 15-ish mph with the 9.9, nice for getting somewhere and enough to insure a margin of safety.

    That is my opinion. Mileage may vary...
    Clean feet are happy feet; same for boats.
    1964 MFG Niagara Deluxe

  6. #6
    Admiral CATransplant's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Almost all v-hull 12' boats are rated for 10 hp, so I'd get the 9.9. It'll plane you out, and that's the key to going upriver. With the six, not so much. I use my 6hp on the Mississippi, though, up here in Minnesota. I avoid the river when there's a lot of current, since it's a drag running against it.

    Sure...go ahead and laugh at my old aluminum boat. It's paid for!

  7. #7
    Lieutenant Commander bowman316's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I saw an ad for a 7.5 HP honda engine. selling for $250 bucks.

    I think that would get the job done, But you never hear anything about honda engines, Idk if they are good or not.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  8. #8
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    least 9.9 i got a 10hp 2 stroke and with me and buddy about 135 and 110-115between the both fo us and some gear plug gas we plane out pretty good if he sat in the front. my boat was a flat though with a vi hull in front. would suggust leats 9.9

    forget the honda its 4 stroke
    -1964 20Ft Riviera Cruiser, 1961 14.5Ft Critchfield, 1962 15ft Orlando Clipper
    -1959/60 10 Hp Evinrude, 1961 Mercury 500, 1958 35 Hp Johnson (Sold), 1990 25 Hp Johnson (Sold), 1985 60 Hp Johnson

    1962 Orlando Clipper 15FT http://forums.iboats.com/showthread....hlight=orlando

    http://photobucket.com/sgdteam

  9. #9
    Lieutenant Commander bowman316's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    yea, 4-strokes are way too complicated for that size of engine. And too much weight.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  10. #10
    Supreme Mariner kenmyfam's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Go with the max you can. Best for fighting currents and some reserve power. The difference in fuel is hardly noticeable.
    Marada 2100 Executive Series, 5 Litre V8 with Mercruiser Alpha 1 outdrive. 2007 K-Z Spree 260 RBH, all = a whole lot of family fun !!!!

  11. #11
    Vice Admiral 5150abf's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Had a 12' tinny with an old ('64) 9.9 on it and it did really well in my river, currents would get pretty heavy at times and I never had a problem.

    With just me in th boat and the eight spread out just right it would really move out.

    A 6 will do but a 9.9 would be better.
    GO IRISH!!!!

  12. #12
    Lieutenant Mark_VTfisherman's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Quote Originally Posted by bowman316 View Post
    I saw an ad for a 7.5 HP honda engine. selling for $250 bucks
    I don't care for Honda's but that is not the point. Get a 9.9.
    Clean feet are happy feet; same for boats.
    1964 MFG Niagara Deluxe

  13. #13
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I used to run a 12ft with a 6 hp, and always wished I had something like a 9.9 on it. If you find a killer deal on a 6 hp though you should be okay.

  14. #14
    Petty Officer 1st Class Bard1's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    9.9 is the way to go.
    WE LOVE FUN STUFF!!!!!

  15. #15
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I have a 12' Duranautic V hull, it runs along ok with a 1978 6 hp Johnson on it but struggles in anything but the very least amount of current with two passengers. I'm close to 300lbs, and add a passenger and some tackle, and were pushing 600lbs, it moves the boat but not very fast. My 9.9 does a lot better but still isn't super fast. I actually do better with my older 9.5 hp Evinrude since its so much lighter and I don't need to carry the 75lb battery.
    I have a Honda 10hp, it's an older Honda 100 4 stroke, it runs great but outweighs my Johnson 25 hp. I wouldn't even consider hanging it on my 12' boat. I believe their 7.5 hp motor is based on the same motor?

    I'd go with no less than the 9.9 hp. The best thing I did to mine was to put the 15hp carb on my 9.9, that woke the motor up enough so it at least has enough power to get the boat well on plane and moving along at a nice pace.
    My Duranautic is rated for 10hp max and 540lbs.

  16. #16
    Admiral CATransplant's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Just to add a small note: The 6 hp I use is fine for me, since I'm almost always on small lakes. I use it on the river, but only when I'm by myself.

    If you're going to mostly do river fishing, I'd definitely go with the 9.9 or 10 hp. You'll be glad you did.

    Sure...go ahead and laugh at my old aluminum boat. It's paid for!

  17. #17
    Lieutenant Commander bowman316's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    This would be for duck hunting in the winter on islands up in the rocky shallow part of the river.

    Somewhere I would never take my glass boat.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  18. #18
    Ensign Shizzy's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I have a 6HP in my 14'er. with all my gear and a trolling motor she isnt as fast as Id like..... 10 HP would be much better.

    with just me and no trolling motor or gear she zipps around plenty fine.
    '68 Alumacraft FD, '65 Johnson 6HP "The Sea Monkey"

  19. #19

    Question Re: What size motor for 12 ft V-hull Aluminum boat?

    Hello
    What is the motor rating for the boat?
    I have an old 12ft sears V hull--It is only rated for a 7 1/2 HP
    I have a Suzuki 6 HP on it.It is all the motor I want on it. Once in a while I use it up in maine on a river with a strong tidal flow.It seems to handle the
    currant OK.

  20. #20
    Lieutenant Commander Tacklewasher's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    Quote Originally Posted by bowman316 View Post
    yea, 4-strokes are way too complicated for that size of engine. And too much weight.
    I replaced a Johnson 9.9 with a Honda BF100 (10hp, 4 stroke).

    Weighs 75 pounds. Heavier than the 9.9 but still light enough that it was easy to use and I much preferred it over the 2 stroke, especially for trolling.

    I could plane out my 12 foot (rated for 10hp) and hit 26kmh (gps).

    The old blue and white Honda's are great motors, require little added maintenance and are not that much heavier. If you are choosing between a 6hp and the Honda 7.5, I'd go with the Honda.

    But I do think you need a 9.9. Take a look at the old Honda's before deciding.

  21. #21
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    my 12foot is rated to 15hp. kinda of a wide boat i guess.


    ur expect around 20mph with 9.9 or 10 and with a 15hp( if rated for) expect 30+ maybe.


    with a ncie current i would suggest a least 10hp

    but we have to know what the boat is rated for maybe some pictures?
    -1964 20Ft Riviera Cruiser, 1961 14.5Ft Critchfield, 1962 15ft Orlando Clipper
    -1959/60 10 Hp Evinrude, 1961 Mercury 500, 1958 35 Hp Johnson (Sold), 1990 25 Hp Johnson (Sold), 1985 60 Hp Johnson

    1962 Orlando Clipper 15FT http://forums.iboats.com/showthread....hlight=orlando

    http://photobucket.com/sgdteam

  22. #22

    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I bolted a 1976 20hp mercury on my 12 ft aluminum boat, and I find it gives me just the right performance...the boat did give up its own name....
    ITZA HANDFULL

  23. #23
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    I had just about the same boat. 12 footer, 3-4 feet wide, and not real deep. I had a 6hp Merc on it and it would not plane unless I sat in the center seat and extended the tiller. Then it was fine, but not real convenient. Go with a 9.9 it should do the job.

    By the way I weigh about 200lbs if that helps explain/judge the planing & moving up to the center seat issue.

  24. #24

    Wink Re: What size motor for 12 ft V-hull Aluminum boat?

    I have a 1960 Sears 12' aluminum (narrow 48" beam) and put a 6hp Suzuki 4-stroke on it (model DF6).

    With me (175lb) and about 100lbs of gear I get 15mph wide open. Add wind or current and it just goes downhill from there.

    http://www.flickr.com/photos/redcheese/4189714194/

    With two people and the gear, topped out at 12mph.

    If you are taking the motor on and off a lot like I do, the 9hp 4-strokes just weren't an option. The 6hp is 55lbs and the lightest 4-stroke 9hp I could find was an 82lbs. Might not seem like much, but it is. Especially if you're walking it down a slippery boat ramp!

    If you trailer the boat & can leave the motor attached, by all means go for the 9hp. Otherwise, it's hard to beat a 6...especially one with an integral fuel tank. Great for short trips & flushing the motor.

  25. #25
    Moderator Bob_VT's Avatar
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    Default Re: What size motor for 12 ft V-hull Aluminum boat?

    This original thread was started in March 2009 ....... please do not respond to a thread this old and cause it to rise to the top of the forums.

    Thanks!

    Welcome to iboats!
    This is a great link to boat specifications http://boatspecs.iboats.com/
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