Repower from single 2 stroke 150hp Yamaha to twin 115hp

Discussion in 'Outboards' started by Alaska Offshore, Apr 30, 2014.

  1. Alaska Offshore
    Joined: Apr 2014
    Posts: 1
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    Location: Alaska

    Alaska Offshore New Member

    I operate 2 vessels in offshore Alaskan waters, beyond any sort of economical commercial assistance in the event of emergency. I use my Hewescraft Pacific Cruiser 26, with twin 115hp yamahas for cruising, sportfishing and camping. I have another 27 ft bare bones but heavily constructed aluminum workboat, with a single 1996 2-stroke yamaha 150hp. It is a shallow V hull, designed for comm fishing. It planes quickly and is fast as hell when the water is flat, very stable when it is not, and most of my use is trolling or running relatively slowly with the 150. I am very happy with the 115s on my other boat and am ready to upgrade the old 150 2 stroke. The reliability of twins is an important factor, because when it goes wrong here you cant be hanging over the stern futzing with a probably "too small to do much good anyway" kicker. I can pretty easily isolate fuel tanks and elect systems if I decide to go with twins.

    I need help figuring out the balance of reliability/redundancy and fuel economy. I am really leaning toward the twins. The question is not whether the twin 115s will suck more fuel than a single new 150, I know they will, but whether they will use less fuel than the old 2-stroke 150 that I have now.

    All input appreciated.
  2. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Google Yamaha Performance Bulletins, there is a wealth of info in there re the performance and fuel use of their engines single and twin rigs, two and four strokes, on a whole range of boats, which should give you a good basis for decision. One thing to be mindful of is the effect of the increased weight aft, which may not be a problem, but you would be better placed to judge that, or even experiment by placing equuivalent weight back there. Another possible concern is the ability to plane the boat on one engine, if not there, it could mean a long, slow trip home, or a hazard on a barred inlet. Some say the power curve of four-strokes vs two stroke is such that it can mean the difference between being able to plane on one engine of a pair, or not. Sorry to plant that doubt in your mind. :D
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