Small Catamaran engine options

Discussion in 'Electric Propulsion' started by YoungGrumpy, Feb 8, 2021.

  1. YoungGrumpy
    Joined: May 2012
    Posts: 64
    Likes: 4, Points: 8, Legacy Rep: 34
    Location: New Jersey

    YoungGrumpy Junior Member

    Cold and snow and boring, so it's time to work on complex problems!
    The boat is 24 ft, under 2 000lb catamaran.
    Needed:
    - 6 HP or more engine

    - Basic electrical loads

    1. Nav Lights
    2. Cabin lights
    3. Small load charger (tablet/cell phone etc).

    Means of producing El. Power, or recharging the batteries – The boat is at the mooring, so no shore line.
    The simplest and cost-effective approach would be a 9.9 outboard with alternator, and a house battery (or, two batteries, so even el. Start is possible). Small solar panel would make it a very robust system (batteries toppled always, then when the engine is running, more current produced for use). Downside of this approach (based on my current experience) comes since the boat used mostly for daysailing, the engine is used to get from/to the mooring only. Most likely as a result of the irregular/low use and added to the ethanol on the gasoline, carb problems are regular. After needing a tow twice last summer (one time the engine stalled right before entering the mooring field on a breezy day), I am wandering if there is a better system, like El. outboard.
    Something along the lines of
    - Two ePropulsion Spirit outboards should give me enough HP to move the boat nicely (plus, better maneuverability)
    - House battery and a solar panel to recharge the whole (two engines and a house).
    Is it possible to get such a set up for less than twice the outboard price and to get a reliability and a peace of mind? Would it work with no gasoline genset?
     
  2. Rumars
    Joined: Mar 2013
    Posts: 1,047
    Likes: 450, Points: 83, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

    Buy one of the new fuel injected outboards, for example the Tohatsu MFS9.9. No more carb problems, no worries about ethanol fuel.
     
  3. bajansailor
    Joined: Oct 2007
    Posts: 1,733
    Likes: 544, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    What type / make / design of cat is she YG?

    Does she exist already, or are you in the process of building her?
     
  4. fallguy
    Joined: Dec 2016
    Posts: 4,128
    Likes: 681, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    You need to load calc it all.
     
  5. YoungGrumpy
    Joined: May 2012
    Posts: 64
    Likes: 4, Points: 8, Legacy Rep: 34
    Location: New Jersey

    YoungGrumpy Junior Member

    The Seawind 24 is what I have now. The experience with outboards (fuel issues etc.) is what was happening more or less for the last 5 summers. One season with 2-stroke Yamaha 9.9, then I've got Tohatsu 6 hp 4-stroke (a bit less weight, longer shaft). Newer 4-stroke is the worst. With the Yamaha, I would spray some cleaner into the air intake, and when back at the mooring, spray every hole, and it would be good for a month. The Tohatsu stalled one day, and all my efforts would not make it run properly (start, idle and stall if given more power).
    These boats work well on 6 to 15 HP.
    As I am in the process of finalizing the design of a new build (same LOA, bridgedeck cat, foam/glass epoxy, composite instead of alum beams...), new boat should be lighter and faster, so 6 to 9 HP is what I expect to work.
    Fallguy, it is a sailing catamaran, on a smaller side, so displacement speeds up to 7 kts is what is required as power, so price and reliability are the factors, not the power range or, I do not know, loads, dynamics...
     

  6. YoungGrumpy
    Joined: May 2012
    Posts: 64
    Likes: 4, Points: 8, Legacy Rep: 34
    Location: New Jersey

    YoungGrumpy Junior Member

    Looks like I should move to the "Outboards", and chew on the merits of injectors/vs carburetors in dealing with modern gasoline on small boats...
     
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