Manta works out how much fuel is in your tank and what your engine really uses, from a few fuel logs and your engine hours. No tank sensor needed.
Knowing what is in the tank
Most boats have a fuel gauge that is vague at best. Manta gives you a second opinion: an estimated tank level, in percent and litres, based on what you logged and how long the engine has run since.
What you log
A fuel log takes a few seconds. Set the level with one slider, in percent and litres. If you filled up, add the litres that went in. You can log fuel at any time, from the boat page or during a trip.
How consumption is calculated
Manta takes two fuel logs, works out the fuel used between them, and divides it by the engine hours in between.
An example with a 160 litre tank:
| Level | Engine hours since | |
|---|---|---|
| First log | 90%, that is 144 L | |
| Second log, after adding 38 L | 100%, that is 160 L | 12 h |
Before filling up the tank held 160 − 38 = 122 L. So the engine used 144 − 122 = 22 L in 12 hours, which is about 1.8 L/h.
This is why the added litres are worth entering. Without them, Manta would only see the tank go from 90% to 100%.
How the tank level is estimated
From your last log, Manta subtracts the engine hours since then at your boat's consumption. It chooses the most reliable consumption it has:
- Your measured value from the last 12 months
- Your measured value from all earlier logs
- The litres per hour you set in the boat's profile
Between two logs, each trip gets the rate measured for exactly that stretch. So a fill-up in July also tells you what each trip since the last log used.
Engine time comes from your log and from the automatic engine detection. If you forget to log the engine off, the run ends at arrival. If you forget the start, it begins at departure.
What is left out of the average
Not every reading is a good measurement, so Manta doesn't average them blindly:
- Stretches where the hour meter moved noticeably more than the logged engine runs, because a trip is probably missing
- Values far above or below what is usual for your boat
When a new log doesn't fit the last one, Manta asks before saving and shows you what it would mean. Everything is calculated fresh, so correcting an old log updates every figure after it.
What you see
- The current level on the boat page
- Fuel used per trip, month or year, with your average consumption over time
- Fuel used on each trip's charts, even without instruments
- A prompt when you start a recording and the tank looks low
The level is an estimate. Before a long stretch under engine, look at the tank.
Free
Fuel and engine-hour logs, tank level and consumption come with the app, for every boat. The rest of the maintenance log needs Manta Pro.
Questions
Do I need a tank sensor?
No. You log the level from time to time and Manta counts it down with every engine hour. If your instruments report the tank level, you see that on the boat page too.
How many fuel logs do I need?
Two logs with engine time between them give a first measured consumption. From then on, every further log makes it more reliable. Filling up to full each time is the most accurate reading you can give it.
What if I haven't logged any fuel yet?
Manta uses the litres per hour you set in the boat's profile until it has measured a value of its own.
What happens if I forget to log a trip?
If the hour meter moved noticeably more than the logged engine runs, Manta leaves that stretch out of the average, so a missing trip doesn't distort your consumption.
Is it free?
Yes. Fuel logs, the estimated tank level and consumption charts come with the app.