T&T: Diesel Fuel system design

[Mark Andrew]

Greetings Scott, thanks for resending the link to your site.  I've poured
over your schematic to understand your method.  What you did is so close to
what I need to do, that it is very helpful.

A couple differences in our situations, tho.  My boat is 56', a bit shorter
than yours, I assume from the photo.  It used to have a Kahlenberg Diesel
engine 6' tall and 10' long in the engine room (1/3 of the lower deck area).
The engine is now sitting in a marine museum, and was replaced with a Cat
3306 and an added 500 gal fuel tank running fore and aft in the middle of
the engine room.  When we started the renovation, we decided to use half the
original engine room as a master cabin (yes it was that big). We cut off a
couple feet of that 500 gal fuel tank and spun it 90 degrees so it sits
athwarstships now between the two original wing tanks (450 gal each).  That
left a big cavity in the forward end of the engine room for the master cabin
(we had already removed the two old gen sets in the fore of the engine
room).  The original Kahlenberg also ate oil at a tremendous rate, so there
were two 50gal lube oil tanks on one side of the engine room, too.  So this
leads to where our engine room differs..

.the lube oil tanks will now become joined into one 100 gal day tank
(cleanest fuel, next to be burned), the original wing tanks, and the added
(but reduced) "middle" tank for a total of 4 tanks (about 1,400 gal total).
So instead of having a separate T-throw valve to take from either Port or
Starboard tanks as in your scenario, I'm having manifolds made up.  One will
have inputs from all the tanks, and 3 outputs to the engine, gen set,
furnace thru individual Racor 30m filters (the engine getting a dual, like
yours).  The other manifold will have inputs from all the tanks, but then
run to the polishing system thru its 30 micron filter.

For returns, there are again two manifolds, one for the 'users' and another
for the polishing system.

I haven't yet, but need to include a way to transfer fuel to the day tank.
I then plan to most often take from the day tank to the 'users'. (Maybe the
polishing system is a good independent way to transfer from any tank and
return to any other tank [and clean, to boot!], say to move fuel to the day
tank from any tank)

I didn't think of a drain.good idea.

The original Stbd and Port wing tanks have a big 'equalizer' tube between
them, so they fall at the same rate, but valved so they can be isolated, if
necessary.

It appears from your schematic that you use your polishing pump to prime the
'users' filters, and perhaps even to bleed the 'users' when necessary.  Once
you're primed, or bled, do you then throw P1 to close and S1 to open?  Is
that how it works?  Are S1 and your 'priming T' both below the wing tanks in
order to gravity feed after priming?

In my situation, I almost have to put my filters at eye level, so I was
thinking of a small lift pump (Jabsco Junior Gear Puppy, for example) to use
to prime my filters and bleed my 'user' lines. ( I have a follow up question
on this that I'll post separately)

Anyway, these are a few of my thoughts/plans.  If anything jumps out at you
from your experience, feel free to set me straight or have me consider
another alternative.

By the way, nice boat.love the lines.

Mark

 

From: Scott H.E. Welch [mailto:scott at firstclass.com] 
Sent: Tuesday, October 16, 2007 8:57 AM
To: Scott H.E. Welch
Cc: Mark Andrew; trawlers-and-trawlering at lists.samurai.com
Subject: Re: T&T: Diesel Fuel system design

 

"Mark Andrew" <msandrew at chartermi.net> writes:
I recently sent the message below...got some great advise.  One person had
followed up with a link to their site where they had a complete schematic of
their fuel system, including their polishing system.  Somehow I misplaced
the message and link.  Could you resend.  I thought I had set it aside to
take a very close look at it, but evidently set it aside too well.
That would be me, see http://www.islandeagle.net/systems/fuel

Scott Welch
FirstClass Product Manager
www.firstclass.com

Those who make no mistake rarely make anything.