Fuel Line

Discussion in 'Boat Design' started by Danob, Dec 26, 2015.

  1. Danob
    Joined: Dec 2015
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    Location: Santa Cruz, California

    Danob Junior Member

    Hi, I'm new to this site and to boating. I've drawn a rough diagram of my fuel line and was trying to find out how it works. There are two Valves near the starboard A and B and one near the port tank C. Should I leave all Valves open or should I turn off B so that A works the starboard tank and engine, and C works the port tank and engine.

    And If I turn off A and turn on B and C will the port tank feed both engines?

    And if I turn off C and open A and B will the starbord tank feed both engines?

    Am I on the right track?

    Thanks,
    Dan
     

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  2. Barry
    Joined: Mar 2002
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    Barry Senior Member

    This is correct but if one tank gets contaminated and you are feeding all the fuel through both the starboard and port filters, you have the chance of contaminating both filters.
    We had the same config in a Silverton many years ago and just left B closed so each tank had a dedicated filter.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    Agreed, it's really easy to contaminate "other tanks" with inadequate plumbing. I find it best to arrange for isolation, even at the cost of some convenience, particularly with diesel.
     
  4. Danob
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    Danob Junior Member

    Thank you Barry and Par! So if Necessary to empty one tank quicker I could run both engines off either tank just by closing A or C, correct?
     
  5. Barry
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    Barry Senior Member

    yes but opening B for the crossover
     
  6. Heimfried
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    Heimfried Senior Member

    Is a fill nozzle at both tanks? Are you using both while refueling?
     
  7. Danob
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    Danob Junior Member

    Thanks Barry!
    Yes Heimfried each gasoline tank has its own fill nozel and yes I am using both while refueling. I had some work done on the boat and I think they had the starboard A valve closed and the port tank overflowed. It had more gas than I thought. It's all a bit confusing and I'm trying to get the system right. Could one tank nozel fill the other tank and vice versa by turning the valves on or off?
     
  8. Heimfried
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    Heimfried Senior Member

    Yes, if A, B and C are open, it should be possible, to refuel both tanks by using only one fill nozzle.

    But: it depends on the flow resistance of the connection pipe and valves (diameter and so on), if it works within considerable time while refueling. May be the overflow to the other tank is to slow. (I don't know, if there could be a contamination problem with gasoline, I only heard it in regard of diesel.)

    The reason for my question was the following: if the connecting pipe is efficient to refueling only thrue the nozzle of one tank, you should always close valve B unless refueling. (Or close B nearly to restrict fuel flow to the required amount for the consumption of the engin.) Otherwise the stability of your boat will decrease, because of a special case of free surfaces effect.

    E. g. your boot heels towards starboard, fuel will overflow from the portside tank to the starboard tank and streghten the heel. (If the tanks are nearly full or nearly empty, the effect is low, but inbetween it may be annoying.)
     
  9. Barry
    Joined: Mar 2002
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    Barry Senior Member

    "I had some work done on the boat and I think they had the starboard A valve closed and the port tank overflowed. It had more gas than I thought"

    If they were filling the starboard tank with A closed and B open there would have been no connection to the port tank and the port tank should not have over filled.


    I expect that the fill is on the gunwhale flat and utilizes a SEALED fuel fill cap. Sealed so water cannot get into the fuel tank from spray or allow fuel to leak out of it if the boat is heeled. There should not be any opportunity for the fuel to "overflow" the other sides fuel fill.
    Normally, the fuel tank vent is below the fuel fill and fuel can squirt out the vent if you over fill the fuel fill up to the top of it.
     

  10. Danob
    Joined: Dec 2015
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    Danob Junior Member

    Thank you all so much for your replies, I'm going to go over these with my son and will get back a little later.
    What a great Forum!
     
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