engine dilemma-outboard v inboard

Discussion in 'Propulsion' started by arthor, Jun 20, 2009.

  1. arthor
    Joined: Apr 2008
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    Location: UK Yorkshire

    arthor Junior Member

    Greetings all.
    I intend building a Selway Fisher Power 3 next year and have yet to work out my best options engine wise. It was I would say is a semi planing hull and the displacement is down as 6500lbs although I will be extending it by 3-4' so it will be a bit more than that. I have emailed the designer a few times and it can be built with shaft, sterndrive, jet or outboard.
    My usage will be coastal, offshore, estuary and inland with the offshore being really the odd trip to get me to Europe and up to the Baltic. This basically means that for much of the time I will only be doing 4-5 knots but with the occasional blast. Therefore in full power mode, economy isn't a major issue.
    For simplicity of build I was thinking of a large outboard (150 HP ish) with a 50 HP ish kicker/stroke inland motor. With the ever improving economy of petrol outboards and the fact that red diesel is no longer available, I think this is quite a sensible option. Also, Evinrude now do a multifuel outboard that will take diesel.
    Another factor that I considered was that I could allow for a possible conversion to a diesel sterndrive at a later date if I build in engine beds. Another factor is electricity generation. Would I lose out just using a small outboard for much of the time and would a little generator solve that?

    your thoughts gentlemen please??

    regards
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    A generator gives you the option of power without running your main engine. A 50HP should have a small charger, probably 20A or so. Outboards free some interior space, and you can tilt them out of the water. If you have an inboard, you can also install the kicker.
     
  3. Rangerspeedboat
    Joined: Apr 2009
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    Location: Texas

    Rangerspeedboat Senior Member

    Outboard, they are easy to maintain.
     
  4. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Outboard , as on a new design you can probably borrow an engine to assess how much power you really need , and try 3 or 4 to optimize the boat. You might be very satisfied with 50hp , or "need" 300, only a test will tell.

    As a kicker I would look at a Honda 4 stroke of 20 hp or so MAX.

    FF
     
  5. Frosty

    Frosty Previous Member

    Yorkshire as in Hull?
     
  6. arthor
    Joined: Apr 2008
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    Location: UK Yorkshire

    arthor Junior Member

    Yorkshire as in Hull

    Yes to that Frosty.

    Thanks for the feedback gentlemen.
    I have emailed the designer and he is usually very helpful and quick, I just wanted some feedback from you lot out there.
    I think the main thing here is that if I install beds (or make sure any fore aft stringers are beefed up to be beds later), I think I can switch to a sterndrive later.
    I like the idea of being able to assess what power I need as later on, I don't want to overspend on a sterndrive motor.
    I get the idea that having a hefty outboard for occasional use and a kicker for a standby/inland use is sound.
    Is it really possible to run the new multifuel Evinrudes on diesel??? Does anyone know anything about them?? I know the US military has bottomless pockets so economy isn't important but range will be so they must be partial to miserly engines??? I can see the economy of all outboards just getting better and better. The new Tohatsu 2 strokes are supposed to be excellent on juice. What make do you reckon are the best for economy/performance??

    regards

    arthor
     
  7. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    I know the US military has bottomless pockets so economy isn't important but range will be so they must be partial to miserly engines??

    The military is far more interested in Commonality , the ability to fuel everything they operate with a single fuel.

    Think of the supply hassles of a half dozen fuels in a combat area.

    FF
     
  8. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    My neighbor has a Mercury 200 with direct injection. He claims that fuel consumption is approx. half that of his previous Yamaha and the engine weighs much less than a 4-stroke with the same power.

    He also got 5 years unlimited warranty; something you do not get from Mercruiser.
     
  9. uncleralph
    Joined: Jul 2005
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    Location: USA

    uncleralph Junior Member


  10. arthor
    Joined: Apr 2008
    Posts: 46
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    Location: UK Yorkshire

    arthor Junior Member

    hmm

    thought it was too good to be true. I guess that an emergency means its ok to wreck your engine and just order a new one when you make it home (deep pockets).
    Mind you, 16 years in the British army has told me that our military is pretty stingy about things.
    Can't quite work out how diesel and spark plugs get along.
    I have noticed that an Evinrude over here is pretty dear compared with a Tohatsu or Mercury.
    Think I will go with the outboard and make sure I build in sterndrivability for later if I want to. Diesel isn't that cheap over here for boats anymore anyway.

    arthor
     
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