T&T: Fuel Tank Configuration

[John Blackburn]

 The DeFevers are built with both a supply and return manifold.  You can
draw from and return to any of three tanks individually or all at the
same time.  Both engines and the Genny are plumbed into the system.  You
may want to think about something similar with all tanks tieing into
manifolds, with a bypass direct feed to each engine from tanks on its
side.

John Blackburn
44 DeFever "Yak Rack"
Deale, MD

Faure, Marin wrote:

    The tanks can be plumbed together to give a single tank image to the

  engines and generator or they can be separately dedicated to the engines
  and generator. For simplicity I am leaning toward plumbing them
  together. There will be fewer deck fills, fewer weight balancing issues,
  etc. What am I missing? Should I be considering the separate tank
  approach more seriously?
  
  The previous owner of our boat replaced the original three tanks with a
  five-tank system.  Four of the tanks are cubes, two on each side of the
  aft half of the engine room that fill the space that one original tank
  filled, the same idea as what you are contemplating.  The fifth tank is
  a 60-gallon day tank under the floorboards in the middle of the engine
  room.  The engines normally feed from the day tank.  Each of the four
  saddle tanks has a drain and manual valve at its lowest point which,
  when opened, lets the fuel drain via gravity into the day tank.  The
  valves in the system can also be set to allow each engine to draw from
  one of the two saddle tanks on its side of the engine room instead of
  the day tank  But normally the engines and generator draw from the day
  tank.
  
  The fuel return from each diesel is valved so it can be sent either back
  to the day tank (the normal position) or into the forward saddle tank on
  the engine's side.
  
  Each of the saddle tanks has a sight gauge on it with a shutoff valve at
  the bottom end (NOTE: if you install a sight gauge on your tanks, it
  should have shutoff valves at the bottom AND top of the tube, not just
  the bottom.)  The daytank has a sender connected to a fuel gauge at the
  helm.
  
  This system works great and has the advantage of letting us completely
  drain a saddle tank before refilling it.  So there is no "dead" space at
  the bottom of the tank for water and other gunk to collect and sit.
  
  I don't see anything wrong with your notion of plumbing the two tanks on
  each side together.  It might be smart to install a shutoff valve in the
  connection so you can isolate one tank from the tank next to it in case
  of a leak or whatever.
  
  ______________________________
  C. Marin Faure
  GB36-403 "La Perouse"
  Bellingham, Washington
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