Anyone here have a fuel tank transfer system ?

I mean as in an aux smaller fuel tank where you can flip a switch and transfer diesel from the small tank to the large one ? I ask as my new to me boat has this but not a peep about actually using it anywhere in the manual.

It is something the boat manufacturer rigged apparently as an option when new, and the panel is so lame it doesn't even indicate which direction to flip the toggle to start the transfer pump.

Is the system by chance designed to work in the opposite way than your description? It is not uncommon for vessels like ours to have a smaller "day tank" from which the engine(s) feed under normal circumstances. This day tank is then filled periodically with fuel transferred from the larger fuel tanks.

Our boat is like this, with two 85 gallon saddle tanks on each side of the engine room and a 60 gallon day tank in the bilge just aft of the engines. Fuel transfer from the four saddle tanks to the day tank is accomplished via manual valves by gravity not pumps, but with a different tank mounting a pump could certainly be used to accomplish the same thing.

Sixty gallons gives about twelve hours of continuous running as our engines combined burn about 5 gph for 8 knots through the water. In reality it's more than twelve hours since we don't run at our cruise rpm the whole time the engines are running.

To be honest I'm not sure what prompted the development of the day tank concept, but it's not an uncommon setup. Perhaps the intention is to isolate the engine(s) from bad fuel that might be inadvertently taken on into one or more of the larger fuel tanks but I'm just guessing. If someone knows the real reason I would be very interested to hear it.

I sorta wish I had a Day tank. It would really help to accurately measure fuel consumption.
In order for me to transfer fuel from one tank to the other, I just use the fuel polisher pump, helps that I have a timer, otherwise I could really screw things up.

Marin said:

Is the system designed to work in the opposite way than your description?

Click to expand...

I wish it was a two way system. I say this because when I brought the boat from FL to SC one of the days I was not aboard, the captain I hired did the transfer....probably because he was concerned about running out of fuel, which is because the fuel gauge doesn't work ! (send unit really...another tale of woe...)

The next day I get back aboard and notice the boat is listing ever so slightly...which most people would not even notice but drives me nuts because it was dead level when I bought it. I eventually noticed that the aux tank is off center in the construction drawings of the boat. So almost certainly that is why it's now listing...it's missing the weight of the fuel in that off center tank.

Why don't I just go get some fuel and fix that situation ? Well...that's another story...

Anyhoo, the fuel transfer toggle seems to have 3 positions so I wonder if it could transfer the other direction. But the "transfer" light only comes on when I flip it all the way up...so I suspect it's small tank to large tank only. Apparently serving as an emergency source of fuel.

But I don't really know for sure, thus this topic....


While the Viking manual shows the tank in the drawings, there is zero mention of it, or the transfer system anywhere in the literature...not the capacity, nothing...

From your description it sounds like the engines don't or can't feed directly from the small aux tank?

Marin said:

From your description it sounds like the engines don't or can't feed directly from the small aux tank?

Click to expand...

Apparently not as it's dead empty now and yet the boat ran for 20+ hours that way. Still have about 1/2 diesel in main tank (which holds 1030 gallons)


(empty, according to my dowel rod in the sender hole test anyway....according to the "aux tank" gauge it was half full until I adjusted the "empty" pot on the Centroid capacitance sender puck......which is a whole 'nuther topic I should start....what's is the deal with these Centroid send units giving screwball readings ?)

But who knows...maybe there is some secret way to run the engine directly from the smaller tank. R. Lazarra (the designer) might know but I misplaced his phone no ! (plus I doubt he'd be too enthused to talk about such mundane things)