Rethinking the fuel tank situation

Discussion in 'Boat Design' started by the brain, Oct 26, 2016.

  1. the brain
    Joined: Sep 2016
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    the brain Senior Member

    Rethinking the fuel situation

    I currently have a new primary tank connected to the 3 way valve switch and a secondary tank also connected to the 3 way valve.

    This means when both Pri/sec run out I have to disconnect a tube then connect the reserve 6 gallon tank (I’m not likeing this arrangement much).

    I was thinking maybe to come out of each main tank Pri/sec connect into a T fitting
    Then feed both tanks into the 3 way valve then simpley connect the 6 gallon reserve
    To the other side of 3 way valve.

    Edit I have yet to electricalley connect either pri/sec tanks senders to a fuel guage

    The primary tank is a mollier the sec is a automobile Bosh sender (which I have the matching guage)
    ?1.will I need a mollier guage for pri tank? And have two fuel gauges?

    ?2.Or could I electricalley switch on/off between the two tanks using just the Bosh sender I have for both tanks?

    edit pri tank is 19 gallons sec tank is 15.

    attach images of pri/sec tanks

    What do you Guys think of my new plan?

    Thanks STB
     

    Attached Files:

  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The easiest setup is a single valve for each tank. The outlet of the valves get connected together to a manifold.
     
  3. Ike
    Joined: Apr 2006
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    Ike Senior Member

    I'm with Gonzo. Keep it simple. The fewer fittings in a fuel system the less chance of a leak and other screw ups. Frankly I would prefer to have to disconnect one and connect the reserve tank manually, than worry about Y valves and T fittings.
     
  4. Barry
    Joined: Mar 2002
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    Barry Senior Member

    If your valve is manual, then just spend 25 bucks and buy a 4 way valve, and plumb the reserve into position 3
    The 4 ways that we used, Anderson Brass if I remember correctly, had a bottom dump ie to the engine with 3 inlets.
    And to those who are trying to deal with 2 tanks that need a return line, ie most diesels and many gas engines, they also make a 6 port that switches both the inlet and the return at the same time

    The three positions selected the proper tank, and there was a 4th position which shut all the inlets off
     
  5. the brain
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    the brain Senior Member

    Gonzo are you saying to come out of each tank into the fliter so can that be three lines connected to the fliter each line having a petcock valve cutoff/on.


    Gonzo do you have any images of you'r suggestion?


    so it sounds like I will have to have two gauges one for mollier other for mirax?

    attach image of current setup.
    Thanks STB
     

    Attached Files:

  6. gonzo
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    gonzo Senior Member

    Yes, you describe it the way I suggested. Unfortunately, I don't have any images. You can put 2 tees at the filter inlet. That will give you 3 connections. The valves don't have to be directly mounted to the filter, so there is some flexibility for their location.
     
  7. the brain
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    the brain Senior Member

    I believe my fliter has only two in arrows (inlets) two outlets. so I would need a tee for three inputs.

    see currently I have t o remove a hose clamp and pull a tube off a barbed fitting (which isn't working for me).

    I actually have 3 three way valves maybe I could use each one as a peacock?

    Thanks STB
     
  8. Barry
    Joined: Mar 2002
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    Barry Senior Member

    It appears that you have the Anderson style valve type. But because you already own three, then take a second one and plumb the common outlet port of second one into one of the inlet ports of the first. Then hook up two tanks to the second valve

    To get fuel out of tank one:
    Valve one is opened to tank one and valve two is closed

    To get fuel out of tank two
    Valve one is closed to the tank that is hooked to this valve but open to the port that is hooked to the discharge of valve two, valve two is turned to tank two

    To get fuel out of tank three
    Valve one is closed to the tank that is hooked to this valve but open to the port that is hooked to the discharge of valve two, valve two is turned to tank three

    The filter will be between the outlet of valve 1 and the engine as all fuel will run through the common outlet of this valve

    If I was too cheap to buy one valve that had 3 inlets and 1 outlet, I would hook up one port of valve one to the reserve, call this tank one, because it would probably not be used too many times,
    then hook up tank two and three to the inlet ports of valve two

    So valve one stays in one position always (unless you need the reserve) and you are always switching valve two
     
  9. Barry
    Joined: Mar 2002
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    Barry Senior Member

    The other thing that I would look at is the filter should probably be installed vertically. Hard to tell from the picture but for changing it, you will spill fuel on the floor, mind you, you could put a pot under it.,

    But I would be worried about trapping air AND the fuel will not be exposed to the entire area of the filter paper. The filter housing must flood from the bottom with the output at the top.

    Fuel flows into the bowl, fills it completely, then goes out the top into the line heading to the engine.
    The way that you have it, the fuel would slosh around in the bowl and hopefully enough would get into the outlet to the engine.
     
  10. Barry
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    Barry Senior Member

    Some additional points
    The fill has to be outside the boat, ie mounted so any spill will not be in the compartment
    It appears that you have different material on the valve, ie brass valve and aluminum fittings. If they are stainless you are ok but aluminum and brass are not a mix
    Same going into the housing on top of the filter. This will probably be cast aluminum, so stainless or aluminum fittings should be installed
    I cannot see some of the heads on your clamps but a couple appear to be rusted (might be the light) so these clamps are not ABYC approved. Many automotive clamps claim to be stainless and the strap is but often the screw is just galvanized. The screw and strap have to be stainless
    The hose, according to ABYC, needs to meet marine specifications and marine hose is marked as such every foot or so

    There needs to be a vent on the tank, on the outside of the hull. Not the transom
    I expect that you will buy another clamp for the filter head, one appears to be missing

    Splitting hairs.
     
  11. Barry
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    Barry Senior Member


    The automobile Bosch sender will probably not be marine approved but you can worry about this. The gasket on many automotive senders are either cork or a cork and rubber mix.
    These are not ABYC approved as the cork will over time degrade. You need a rubber, neoprene gasket.

    Ensure that you have the instructions when you hook up the guage/sender.

    The sender does not have any power going into it!!!!
    The sender arm/resistor merely changes the resistance. If you are guessing at the hook up and power up the sender, well perhaps you could blow up the tank.

    Re. If one sender is compatible with the other.
    On the gauge or the sender that came with the gauge, ie they will be matched for ohms resistance. If you want to use the same gauge, on a switch, you need to match the ohms range

    I think that there are two "standard" ohms range but may be more and they may be polarity sensitive

    First range say one might be 0- 100 and the other 0-150, you will have to look this up on the net

    The second is polarity, ie one might be 0 ohms empty and 100 ohms filled, and the other might be 100 empty and 0 filled.

    Long story short, the senders have to be the same and matched to the guage
     
  12. the brain
    Joined: Sep 2016
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    the brain Senior Member

    lots of good info here thanks

    I think I will leave the pri/sec tank connected to the three way valve

    then connect the 6 gallon reserve tank directly to the second input of the fliter then when I need the reserve just plug a OMC fitting into the tank.

    I decide to have two fuel gauges one mollier other bosh.

    the mirax tanks sender actually had a cork float if I remember correctly the new bosh sender had a plastic will verifify this later.

    dam I thought I could use the aluimin fittings in brass I got this advice from West Marine tech surrport. also the orginal mirax thank had these aluimin fittings.

    you are right the hose clamps are a mixture of orginale clamps reused and auto clamps.

    all this fueling excluding the mirax is tempuary this winter it will be better installed.

    are you sure I can't legalley use the mollier mounted to floor w/ unsecured vent/fill tube?
    Thanks STB
    thanks again for the tips
     
  13. Barry
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    Barry Senior Member

    ABYC H24,12.3 Caps or fittings connected to the fuel fill with a chain or other flexible connector (your hose) are not considered to be permanently attached

    It appears that you have some brass and some aluminum fittings, so you can use the aluminum on the filter head and the brass on the fuel valve

    If you hook the reserve tank to the other side of the filter you will need to be able to shut this line off so this tank is not able to be drawn off when you draw off the other tank. Either a valve or the portable tank type as you suggested with the spring loaded check valve ( standard outboard quick disconnect would meet the requirement)

    H24.9.5.2 Cork gaskets shall not be used. ( gaskets are what is specified. If your float is cork, and disintegrates in 15 years, you will only lose fuel tank reading capability, not produced a leak if bad cork is used as a gasket)

    You need two clamps to connect the FILL hose to any fitting. Minimum band width, 1/2 inch

    The vent line has to vent overboard so as any fuel that might make its way up the vent line will not spill into the boat.

    Regarding the question of legality of ABYC standards

    ABYC sets standards for construction and installation of components in US waters.
    Obviously they are the result of research and or failures of construction that they are trying to minimize in the futures. I do not know if the Coast Guard can give you a ticket for not following the ABYC standards.
    BUT the standards are reasonable and the Canadian standards almost match exactly the ABYC standards.
    I think maybe IKE, a frequent contributor, has sat on various committees with ABYC about safety matters, and can speak to the issue of legality of following ABYC standards.
    Again, these standards are designed that you don't blow up your boat 10 miles from shore with resulting tragic results. Your family and friends etc.

    The cost to do it right by following the standards (at least for your fuel installation) is minimal.

    The ABYC manual is costly, maybe 400 bucks or so and is probably expensive to produce as it is over 2 inches thick. ABYC can offset the cost by charging for the manual but this high cost keeps important information out of the hands of people such as yourself working on a DIY project.

    If the manual were free on line, or say 5 bucks a year to look at these standards would be available to more people.

    I think that the Canadian Small Craft Standards, might be on line for free. Not sure but as they appeared to have followed ABYC, and you might be able to find parallel information there for free
     
  14. gonzo
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    gonzo Senior Member

    You are not required to follow ABYC standards. However, then the burden of proof that the material or method meets legal standards is on you.
     

  15. Barry
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    Barry Senior Member

    A question that I have always wondered about is if you started a fire in a marina and the insurance company discovered that you had not followed the standard, could they walk on a claim on either your boat or others?

    Haha, I am not asking you for a legal opinion, just wondering.

    Lots of fine print in the insurance policy

    The reason that I often wondered about this is that the last boat that we owned, the builder advertised that it was built to ABYC standards. But as we built smaller boats to 36 feet and I had extensively read the manual, there were many areas that the standards were not met. Ie the batteries were not in a properly vented box, no toe rails, etc, cannot remember the rest. So if a deficiency that did not meet the Standards, caused an problem, could the manufacturer be sued
     
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