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Old 21 October 2013, 10:27   #1
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Single to twins conversion

I wonder if anyone can help shed some light on the implications of swapping a boat from single engine to twins. The boat itself is a 8m Humber and can take the additional weight on the transom.

My main question is to do with the fuel tank, it currently has a single 12mm outlet from the tank and the run to the engine is fairly short. In an ideal world you'd have twin fuel tanks but as this is a major job would it be possible to run twin 200hp's off the single outlet or would the flow be reduced so much that another outlet would be required?

Obviously I'm then looking at twin batteries etc but I would have twin batteries as a matter of course if it was a single engine rig anyway.

Thanks in advance

Alex
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Old 21 October 2013, 10:35   #2
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Personally I think you'd need another outlet. E.g. the spec for Etecs above 90hp is 3/8id (10mm) fuel line, running 2x200hp engines off 1 12mm outlet risks fuel starvation which can be catastrophic for modern engines. Just IMHO of course.
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Old 21 October 2013, 10:39   #3
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With twin outboards I expect you will need three batteries. That seems the norm these days.
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Old 21 October 2013, 10:46   #4
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Thanks for the quick replies, batteries aren't to much on an issue, it's the fuel situation as that will require fairly major work to add another outlet. Just trying to gauge people's opinions and experiences....
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Old 21 October 2013, 11:19   #5
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Instead of putting in another pickup tube and outlet the same size as the current would it be easier to have one very oversized pickup tube and outlet say 1"? Then immediately split into 2 x 3/8" (or whatever size your engine require) The oversized section eed not be hose, that could be built from SS pipe, with a small manifold at the top of your tank distributing fuel. Not sure its any easier overall but could be done through one access port in your deck instead of making a second.
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Old 21 October 2013, 11:23   #6
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I converted my rib from single 250 to twin 150's at the beginning of the year. I have a single tank. I bought a T connector that connects to the pickup and they spit at the T into Separate water separators and onto the engines. It run's on a single engine fine and we have done 220 hours without a hitch.
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Old 27 October 2013, 05:56   #7
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Thanks for the input guys, much appreciated. I think for the time being I shall look for a large single as it seems the easiest choice
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