410: lagoon fuel tanks

[Mark Adamson]

I have just purchased my first cat a Lagoon 410 S2. I am perplexed as both fuel tanks were full on delivery, but having done some miles now the stb tank is showing 1/4 full but the port tank is still showing full. The dial resets on ignition back to full so think it is working OK, Does anyone know if there is a switch over from tank to tank or do both engines have a dedicated tank and it is probably my fuel gauge that is faulty, I have looked everywhere for some kind of tank switch valve but cannot find? Thanks in advance!

[Wanderlust]

There is no fuel transfer system as standard, but could have been added aftermarket. If you can't find it, it probably doesn't have one.

Maybe your starboard tank was not completely full at the beginning, or the sender on the port tank is sticking.

Both my gauges read full for quite a while. It probably uses 20-25 litres before the gauge moves. Does that equate to "Having done some miles"?

[Sid at SailAway]

Originally Posted by Mark Adamson

I have just purchased my first cat a Lagoon 410 S2. I am perplexed as both fuel tanks were full on delivery, but having done some miles now the stb tank is showing 1/4 full but the port tank is still showing full. The dial resets on ignition back to full so think it is working OK, Does anyone know if there is a switch over from tank to tank or do both engines have a dedicated tank and it is probably my fuel gauge that is faulty, I have looked everywhere for some kind of tank switch valve but cannot find? Thanks in advance!

Hey Mark, On my 410 the tanks are independent of each other as all 410 fuel tanks are. Someone could have modified the system but not sure what purpose it would serve unless there was an auxiliary tank involved. In any case, my advice is to never trust a fuel gauge on any cruising boat. They are so unreliable as to be useless.

The most effective way to measure how much fuel is left is to figure out what you burn per hour on each engine. On my 410, and yours should be close to this, at 2800 rpm each engine burns .6 gallons per hour. Over four years of cruising has proven this to be a reliable number. So we take the 23 gallons one tank holds and divide that by .6 and come up with 38 hours of runtime. Fill up your tanks and after 10 hours or so refill them. Check how much fuel it took to refuel and how many hours you ran, do the math and that should give you your burn rate. Do this several times for more accuracy. When I'm planning our fuel stops I use a .75 GPH burn rate as a safety factor. If you don't have hour meters, now is the time to add them as the meters in your tachometer either have, or will fail. Hope this helps..

[tico]

Hello Mark,

the pipe that goes down to the fuel tanks holds at least 20 litres, if not some more.

The sensor sits at the top of the fuel tank and does not consider the content in the pipe. Probably, one of the pipes was holding extra fuel, whereas on the other side there was no additional fuel in there...