Yes, here you find how we calculate the fuel usage of TOM, like the content of the diesel
tank, and how long we can actually run on a full tank. And more important, when we need to refuel.
This information is very important for "Routes Planned" and if we have to refuel before
we are going on the trip. The fact that TOM uses around 2 liters per hour, when on cruising speed,
makes it easy to calculate.
Not everywhere you can get diesel along the routes. Alot of the fuel-stations are gone, due to
rules and regulations, or because of change of owners, or even otherwise.
When you plan routes, you should know the dimensions of your boat. We use the above dimensions
and that works fine for us. The 2,40 meter height (air draft) is actually 20 cm higher than the tent
is. So that is 20 cm of safety for us. But besides that, you should also know the
fuel-usage of your vessel. This page contains alot of tables with numbers. Boring, I know. But
still very, very nessesary.
Fuel consumption vs Distance
Planning consumption 2.0 L/h · Tank 75 L · Ø 35 cm · length ≈ 78 cm
Core insights
An engine burns fuel based on resistance (waves, wind, hull drag), while the distance you actually travel
depends on SOG (Speed Over Ground), which is strongly affected by wind & current.
Rule of thumb: Always judge fuel use using L/handSOG (plus wind + current).
Why liters per hour does not equal distance covered (current + wind matter).
Make a very conservative fuel planning. Always use the highest usage of your engine. Calculating yourself
rich will actually get you in trouble!
Fig.2 - 10 Liter Jerrycans.
We explain here, with our Tom as example, how wind and water can influence your fuel usage. The weird thing is,
that your usage per hour will (normally) not change. The distances travelled will differ. Down here, you find some
scenario's that explain the usage in some situations. Keep those in mind because just measuring on a map and using
your calculator, will not work.
You should always plan for, and keep reserve fuel on board. For this reason we use four 10 liter metal Jerrycans
that can withstand some "abuse". Also, they will not explode, nor leak. And they are easy to fit in several places
within the engine compartment. The size of those 10 liter cans are convenient and they come in different shapes.
The advantage of using 10 liters, is that they are easy to handle and you carry them to a fuel-stations without
feeling your arm(s) being strechted until your knuckles hit the floor. The fact that we use 4 of them, gives us
a reserve fuel amount of 40 liter. Which technically is 20 hours of fuel for our Tom. Besideds this, the size is also nice
to handle. Not only to get fuel, but also for storage.
Reference boat data (example)
Cruise speed through the water (STW): 5 kn
Fuel consumption at cruise: ~2 L/hour
Conversion: 1 kn = 1 nm/h = 1.852 km/h
At 5 kn you cover 5 nm/h (≈ 9.26 km/h). Ideal fuel-per-distance:
0.4 L/nm (≈ 0.216 L/km).
Scenario 1 — No current, no wind (ideal)
STW: 5 kn • SOG: 5 kn
Distance: 5 nm/h (≈ 9.26 km/h)
Fuel: ~2.0 L/h
✅ Fuel use per hour matches the expected distance at cruise speed.
Scenario 2 — Head current, no wind
Current: −1 kn • STW: 5 kn • SOG: 4 kn
Distance: 4 nm/h (≈ 7.41 km/h)
Fuel: ~2.0 L/h
Fuel per distance: 2.0 / 4 = 0.50 L/nm (worse than baseline 0.40)
⚠️ Same liters per hour, but you cover less distance → higher fuel per mile.
Scenario 3 — Head current + headwind (worst case)
Current: −1 kn • Wind: against
Engine load: increases (more resistance)
Example fuel: ~2.4 L/h
Distance: ~4 nm/h (≈ 7.41 km/h)
Fuel per distance: 2.4 / 4 = 0.60 L/nm
❌ Double penalty: less distance and more liters per hour.
Scenario 4 — Head current + tailwind
Current: −1 kn • Wind: from behind
Engine load: lower than with headwind
Example fuel: ~1.8 L/h
Distance: ~4 nm/h (≈ 7.41 km/h)
Fuel per distance: 1.8 / 4 = 0.45 L/nm
✅ Still less distance than baseline (because of current), but more efficient than scenario 3.
Scenario 5 — Following current + headwind (efficiency depends on SOG)
With current helping you, SOG increases. Even if headwind raises L/h, you may still travel farther per hour.
Current
STW
SOG (kn)
SOG (km/h)
Example fuel (L/h)
Fuel per distance (L/nm)
+1 kn
5 kn
6
11.11
2.3
2.3 / 6 = 0.38
+2 kn
5 kn
7
12.96
2.4
2.4 / 7 = 0.34
+4 kn
5 kn
9
16.67
2.6
2.6 / 9 = 0.29
✅ Even with headwind increasing fuel per hour, strong following current can make fuel-per-distance better, because SOG is higher.
Viksund 27 Columbi Diesel Planner
Planning consumption 2.0 L/h · Tank 75 L · Ø 35 cm · length ≈ 78 cm
Refill Guidance (based on 2.0 L/h)
Scenario
Refill at %
Hours until reach %
Liters at %
Approx height (cm)
Start: 100%
25%
28.12 h
18.75 L
10.4
Start: 100%
20%
30.00 h
15.00 L
8.9
Start: 75%
25%
18.75 h
18.75 L
10.4
Start: 75%
20%
20.62 h
15.00 L
8.9
Tip: Keep a reserve of 20–25% (15–19 L). Refill by 25% for margin.
Per-5-centimeter Table (Height → Liters)
Horizontal cylinder Ø 35 cm · length ≈ 78 cm · capacity ≈ 75 L
When you have a cylinder-shaped tank, that is lying on it's side,
you do not have the same amount of fuel on each (horizontal) level.
Therefore we calculated the levels at certain centimeters. This table
gives a per 5 centimeter calculation.
Fuel Sight Glass — 5 cm Reference (FULL → EMPTY)
Tube (cm)
Reading
Fuel (liters)
Hours remaining @ 2 L/hour
Liters in this 5 cm band
35 cm
FULL
75.0 L
37.5 h
—
30 cm
68.5 L
34.2 h
6.5 L (35→30)
25 cm
57.4 L
28.7 h
11.1 L (30→25)
20 cm
44.3 L
22.2 h
13.1 L (25→20)
15 cm
30.7 L
15.4 h
13.6 L (20→15)
10 cm
17.7 L
8.8 h
13.0 L (15→10)
5 cm
6.6 L
3.3 h
11.1 L (10→5)
0 cm
EMPTY
0.0 L
0.0 h
6.6 L (5→0)
Values are approximate; “Liters in this 5 cm band” varies with curvature.
For finer interpolation, assume ~1 L/cm near bottom & top, ~2.5 L/cm mid-height.
Hours → Level (Start: 100%)
2.0 L/h · From full (75 L) down to empty
Hours elapsed
Liters left
Approx level (cm)
Tank %
0
75.00
35.0
100%
2
71.00
31.4
94.7%
4
67.00
29.3
89.3%
6
63.00
27.4
84.0%
8
59.00
25.7
78.7%
10
55.00
24.1
73.3%
12
51.00
22.6
68.0%
14
47.00
21.1
62.7%
16
43.00
19.7
57.3%
18
39.00
18.3
52.0%
20
35.00
16.9
46.7%
22
31.00
15.5
41.3%
24
27.00
14.1
36.0%
26
23.00
12.7
30.7%
28
19.00
11.3
25.3%
30
15.00
8.9
20.0%
32
11.00
7.4
14.7%
34
7.00
5.2
9.3%
36
3.00
2.9
4.0%
38
0.00
0.0
0.0%
Hours → Level (Start: 75%)
2.0 L/h · From 56.25 L down to empty
Hours elapsed
Liters left
Approx level (cm)
Tank %
0
56.25
24.6
75.0%
2
52.25
23.0
69.7%
4
48.25
21.5
64.3%
6
44.25
20.0
59.0%
8
40.25
18.5
53.7%
10
36.25
17.1
48.3%
12
32.25
15.7
43.0%
14
28.25
14.3
37.7%
16
24.25
13.0
32.3%
18
20.25
11.6
27.0%
20
16.25
9.4
21.7%
22
12.25
7.9
16.3%
24
8.25
6.2
11.0%
26
4.25
3.7
5.7%
28
0.25
0.6
0.3%
29
0.00
0.0
0.0%
Per-centimeter Table (Height → Liters)
Horizontal cylinder · Ø 35 cm · length ≈ 78 cm
Height (cm)
Liters at/below height
Liters in this 1 cm band
0
0.00
—
1
0.61
0.61
2
1.71
1.10
3
3.11
1.40
4
4.75
1.64
5
6.57
1.82
6
8.52
1.95
7
10.57
2.05
8
12.68
2.11
9
14.83
2.15
10
17.00
2.17
11
19.17
2.17
12
21.32
2.15
13
23.43
2.11
14
25.48
2.05
15
27.43
1.95
16
29.25
1.82
17
30.89
1.64
18
32.29
1.40
19
33.39
1.10
20
34.00
0.61
21
34.61
0.61
22
35.71
1.10
23
37.11
1.40
24
38.75
1.64
25
40.57
1.82
26
42.52
1.95
27
44.57
2.05
28
46.68
2.11
29
48.83
2.15
30
51.00
2.17
31
53.17
2.17
32
55.32
2.15
33
57.43
2.11
34
59.48
2.05
35
61.43
1.95
“Liters in this 1 cm band” varies because of the tank’s curved shape. Use the height at your dip point for best accuracy.
Stay tuned for updates on our journey!
We try to update this website as often as possible!
Our upgrade plans.
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