10' Tunnel Hull - how much HP?

Discussion in 'Powerboats' started by fchawk, Mar 27, 2010.

  1. fchawk
    Joined: Mar 2010
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    Location: mass

    fchawk New Member

    I just got this and I am trying to put a rig together here. I have never had a Tunnel hull before but always wanted one. was thinking of trying a 40hp. Scary? She weighs around 140lbs and is solid. When I floated her it say about 2" sbove the waterline.
     

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  2. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Looks fun and perhaps similar to the Thundercat type inflatable tunnel hulls - a little smaller/lighter. 20-40HP?
     
  3. tunnels

    tunnels Previous Member

    50 HP 4 CYLINDER MERC AND PUT THE FUEL TANK UP UNDER THE FRONT DECK . TUNNELS NEED HP SPECIALLY SMALL TUNNELS !! DONT UNDER POWER IT !!:D :p
     
  4. Zappi
    Joined: Oct 2008
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    Location: Puget Sound

    Zappi Senior Member

    Not even close to a Thundercat inflatable. TCs have asymetrical hulls by inflatable sponsons. Thundercats are rated for 50hp.I fear overpowering on this boat may be ummm... Not so good??? All you can do is try but I'm thinking 25hp is realistic.
     
    Last edited: Mar 30, 2010
  5. Zappi
    Joined: Oct 2008
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    Location: Puget Sound

    Zappi Senior Member

    Whats your definition of waterline on your particular boat?
     
  6. tunnels

    tunnels Previous Member

    YOU WILL BE DISAPOINTED WITH A 25 HP I CAN PROMISS YOU !GET 2 PEOPLE AND A COUPLE OF TANKS OF FUEL AND WHAT EVEN AND ALL OF A SUDDEN THE 25 WILL BE LABOURING ITS LITTLE INSIDES OUT JUST TO GET UP ON TOP ! A 50 HP ON THE OTHER HAND WILL GET YOU UP EFFORTLESSLY AND AWAY WITHOUT TO MUCH PROBLEM !! SMALL TUNNELS TAKE A LOT OF PUSHING TO GET OVER THE HUMP AND ITS BETTER TO JUMP RATHER THAN STRAIN . YOU DONT HAVE TO GO EVERY WHERE FULL THROTTLE !!! BUT ITS NICE TO HAVE THOSE EXTRA GEE GEES THERE .
    OK HOW DO YOU FEEL ABOUT 115HP V4 YAMAHA ON A 14.6 SEMI CABIN BOAT ??THATS WHAT I GOT !! ITS HEAVEN !
    I CAN CRUISE ALL DAY FOR MILES AND MILES AT 2750 TO 3250 RPMS AND ITS ECONOMICAL AT THAT SPEED . GET INSIDE A BAY WITH SMOOTH WATER AND GET UP TO 4500 AND IT FLY'S ! IN THE EARLY MORNINGS WHEN THE WATER IS LIKE A SHEET OF GLASS ITS 6200 RPMS AND ITS EXILLIRATING TO SAY THE LEAST , WITH 4 ADULTS IT GETS ON THE PLANE QUICKLY AND WILL STAY THERE REGUADLESS OF THE SEA CONDITIONS JUST NEED TO FIND THAT MAGIC SPEED !! THATS MY BOAT ON THE AVATAR AT THE TOP OF THE PAGE
     
  7. Zappi
    Joined: Oct 2008
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    Location: Puget Sound

    Zappi Senior Member

    No argument... Overpowered is easier to deal with and in many ways more user friendly. I run a 25 hp on a 9 ft rib rated for 10 hp. My thoughts are... That hull design doesnt look to be a fantastic design. Almost reminds me of half Livingston (uggh) and half flat bottom. There doesnt look to be much flotation at the stern to support much bigger than 25. IMHO
     
  8. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Stand on the transom and if it breaks off, flips or sinks, the smaller engines are recommended :).
     
  9. fchawk
    Joined: Mar 2010
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    Location: mass

    fchawk New Member

    OK, looks like I will do the 40hp Thanks all for the very qualified info, I appreciate it and it is always an education whenever I visit this site. I will let you know either way on the outcome
     
  10. tunnels

    tunnels Previous Member

    Mercury did a really nice 4 cylinder 40 hp ! Was a sweet motor and loads a grunt plus has power trim . :D :p
     
  11. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    you need to put a weight in the back equivalent to your intended outboard .and a couple of people in it ....swimming pool is good for tests !!!! .look at the photos below and you will see why .its quite low in the water though fine and stable on the plane..this has a 25 hp 2 stroke yamaha weighs 35 kg (80ib) ..with a smaller hull you can run more pitch on the prop this has a 4 blade 13 pitch and a full size whale tail.....
     

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  12. SpiritWolf15x
    Joined: Apr 2010
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    Location: Vancouver, Canada

    SpiritWolf15x Senior Member


    I have that motor on my 15.5 Hourston, planes 4 large adults without a hitch and holds a steady 16-17 knots easily enough with those 4 adults on board.
     

  13. tunnels

    tunnels Previous Member

    The problem with under powering a boat is you are always frustrated when ever you use it . Theres always that feeling a guy in a rowing sciff is going to pass you,or even a decent sort of a sailing cat ! worse still someone on a windsurfer . :mad: Theres also the thing of a small outboard stuggling its poor little guts out from idle to planning speed and nothing in reserve . :eek:
    Having a few extra gee gees is good ,you can safely cruise at a comfortable speed and cover a lot of ground ! if you are by your self or with the boat loaded you know there is a point that the boat will ride and handle nicely without screaming its poor heart out .:D
    Your motor will last longer and all in all probably be more economical as well .:p Have been in the situation a few times with 4 up and a heap of dive gear and a 70 hp really struggling getting up on the plane and holding it there !, never again !!:( Change the 70 to a 90 and everything changes, even used less fuel on the same trip . :p
     
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