Sorry, couldn't resist the subject line!

We're replacing the two 200 gallon fuel tanks on Sanderling. Apparently
the boat was built around the tanks, as we had to cut them into pieces
for removal since there was no way to get them out of the engine room
through the existing deck plates and doors/hatches/windows. conversely,
we couldn't duplicate the original tanks and get them aboard.
Consequently, each single 200 gallon tank is going to be replaced with
two long tanks, each inboard and outboard of the other.

Other than dealing with fabricating two tanks in place of one where
there are no rectangular surfaces, the next issue is how to fill the two
tanks. The outboard tank can readily be connected to the existing fill
and vent fittings - it's almost a straight shot from the deck to the top
of the tank and the fill fitting. The second tank will need a second
fill (and vent), and that fill will be approximately two feet inboard of
the location of the outer tank's fill. The tanks will be connected at
the bottom lower corners for the 1/2" fuel pickup line, so they will be
essentially self-leveling. The ends of the tanks (fore and aft) are
accessible while the top is accessible only through deck plates cut
above the location of the fittings. The vent outlet for the tanks will
be approximately two feet above the top of the tanks, so there is little
likelihood of fuel backing up through the vent and spilling overboard
(no more opportunity than on the original tank).

I want to be able to fill both tanks on each side with one stop at a
fuel dock and don't want to get involved with filling one tank, pumping
that fuel to the second tank, and then refilling the first tank. That
would be way more complicated and take way too much time.

One option (the one favored by the owner of the boat yard) is to add a
second deck fill leading directly to the second/inboard tank, and create
a separate vent for that tank. That option might result in a low area
of the fill hose where fuel would stay until the motion of the boat
"rocked" it into the tank.

Questions:

(1) For a fill hose/line, is it permissible/safe to place a "T" in one
fill line with a branch to the second tank fill fitting (so both tanks
could be filled from one deck fitting)?

(2) Is it permissible to use a 90 degree fill fitting on the top of the
inboard tank to receive the fill hose/line (rather than coming straight
up) without increasing the height of the fill line above the tank
(there's limited space between the deck above the tanks and the top of
the tank). If so, is there a height/clearance requirement for the bottom
of the tube that runs parallel with the top of the tank to be above the
top of the tank?

(2) Would it be permissible to join the tanks at the top of each side
(not the top of each tank) to eliminate even the extra vent line?

--
<><><><><><><><><><><><>Mozilla Thunderbird<><><><><><><><><><>
Bob McLeran and Judy Young              Manatee Cove Marina
MV Sanderling                            Patrick Air Force Base
DeFever 41 Trawler                      Melbourne, Florida
Blog: http://mvsanderling.net/Blog
Web: http://cruising.mvsanderling.net/

Bob,

I think that most “experts” would never go with a T, and would go with just one deck fill, one hose, one tank fill.

I think you MIGHT be OK if the “T” was in a place where it can be viewed and in necessary, replaced.

I THINK that it may be appropriate to conside a valve manifold in lieu of the T, but am not yet completed the entire “think out” process as to
why this is better than a T.

If the flu line requires a 90 degree T, this should be out in the open capable of being viewed.

On my fuel tanks, it is a straight run from the decking fitting to the fuel fill pie. My interconnecting lines are between the tanks themselves. (They are on the sides of my tanks, because effectively, they are integral with the hull.)The designer called for more than two (think I have 8 between the fore and aft tanks) and I forgot the reasoning for so many, but there was a good one.

My tanks were hydrostatically tested to some 2 bar with a Lloyds guy observing the test. So my vents and fills all have pipe threads to allow for a capped closure for this test. Per Lloyds, the fill and vent  tubes had to be doubled clamped below these threads.

And I do have an overflow line between my aft tank and my forward tank that comes out the side of the tanks. This line has its own twin isolation valves, a “no step” sign CLEARLY visible, and is located in a place I can inspect quite easily. Per Lloyds, these valves can only be opened during fuel fill, and must be closed and locked closed otherwise. Annual, I am allowed to cycle these valves for maintenance, but only one at a time.

These Lloyds boys are into the details.

Lee

On 2015-03-02, at 0033, Bob McLeran via Trawlers-and-Trawlering trawlers@lists.trawlering.com wrote:
………
Questions:

(1) For a fill hose/line, is it permissible/safe to place a "T" in one fill line with a branch to the second tank fill fitting (so both tanks could be filled from one deck fitting)?

(2) Is it permissible to use a 90 degree fill fitting on the top of the inboard tank to receive the fill hose/line (rather than coming straight up) without increasing the height of the fill line above the tank (there's limited space between the deck above the tanks and the top of the tank). If so, is there a height/clearance requirement for the bottom of the tube that runs parallel with the top of the tank to be above the top of the tank?

(3) Would it be permissible to join the tanks at the top of each side (not the top of each tank) to eliminate even the extra vent line?