Intelligence · Fleet

Ship Performance Curves

Main-engine fuel follows the propeller law — burn rises with the cube of speed. Each segment is anchored to its vetted design speed, then overlaid with the speed its fleet is steaming now: the slow-steaming reality.

segments

Analytics

Decarbonization banked in slow-steaming

The underway sampled fleet is steaming ~22% below design speed right now — at today’s service speeds the main-engine per-day burn runs ~51% below design-speed operation. But that single figure is weighted to bulkers, who are 72% of the underway sample: bulkers steam ~18% below design, while container ships steam ~37% below — so the fleet number spans a wide range.

From ~10.5k vessels currently underway at the latest fix (excludes anchored/idle) — a live snapshot, not the whole fleet. The burn figure is the per-day main-engine cut; for the same transport work (per voyage) the cut is smaller, ~1−(V/design)², because a slower ship spends longer at sea.

One propeller law, four fleets

Every segment plotted on the SAME burn ∝ speed³ curve by its live operating point — so how deep each fleet slow-steams, flattened when each card was normalised to its own design speed, is a rank you read left-to-right.

One propeller law, four fleets

each dot = a segment steaming now

steaming now (operating point) design speed burn ∝ speed³

Speed retreat & its spread

ordered by depth of slow-steaming

design speed steaming now 10th–90th percentile of speed

Rank by retreat. Container ships steam furthest below design — 13.3 against 21.0 kn, ~37% slower, which drops main-engine burn to ~75% below design speed — while gas carriers slow-steam least (13.7 vs 16.0 kn, ~14% slower, ~37% burn cut). Tankers and bulkers sit between. Spread. Some fleets hold to one service speed, others are a heterogeneous mix: container ships and gas carriers span ~9 kn between the 10th and 90th percentile of speed, while bulkers hold to ~4 kn — so the single median is a firmer read for the tight segments.

By segment

Design speed, the speed each fleet is steaming now (with its 10th–90th-percentile band), and the resulting main-engine burn against the design-speed reference.

Dry Bulk

7,575 underway at the last fix

Design speed

13.5 kn

Steaming now

11.1 kn

10–90th pct 9–13 kn

Main-engine burn

~18 t/d

~32 t/d at design speed

Burn cut

44%

less fuel per day

Tankers

851 underway at the last fix

Design speed

14.5 kn

Steaming now

10.9 kn

10–90th pct 8–13 kn

Main-engine burn

~21 t/d

~50 t/d at design speed

Burn cut

58%

less fuel per day

Container

1,915 underway at the last fix

Design speed

21.0 kn

Steaming now

13.3 kn

10–90th pct 9–17 kn

Main-engine burn

~38 t/d

~150 t/d at design speed

Burn cut

75%

less fuel per day

Gas (LNG/LPG)

118 underway at the last fix

Design speed

16.0 kn

Steaming now

13.7 kn

10–90th pct 9–17 kn

Main-engine burn

~60 t/d

~95 t/d at design speed

Burn cut

37%

less fuel per day

Method: main-engine fuel scales as (speed / design speed)³ — the propeller / Admiralty law — anchored to each segment’s vetted design speed and a representative consumption, so the slow-steam % is robust while the absolute t/day is representative. The “steaming now” speed is the live median of underway vessels in the segment (we observe the speed and anchor the burn to physics, never the reverse). A design speed is one class-average per coarse segment while the observed median spans every size class in it, so a per-segment % is a coarse-segment approximation. This curve is the substrate the route economics, carbon-cost and TCE estimates draw on.

Intelligence · Fleet

Ship Performance Curves

segments

Analytics

Decarbonization banked in slow-steaming

One propeller law, four fleets

each dot = a segment steaming now

steaming now (operating point) design speed burn ∝ speed³

Speed retreat & its spread

ordered by depth of slow-steaming

design speed steaming now 10th–90th percentile of speed

By segment

Design speed, the speed each fleet is steaming now (with its 10th–90th-percentile band), and the resulting main-engine burn against the design-speed reference.

Dry Bulk

7,575 underway at the last fix

Design speed

13.5 kn

Steaming now

11.1 kn

10–90th pct 9–13 kn

Main-engine burn

~18 t/d

~32 t/d at design speed

Burn cut

44%

less fuel per day

Tankers

851 underway at the last fix

Design speed

14.5 kn

Steaming now

10.9 kn

10–90th pct 8–13 kn

Main-engine burn

~21 t/d

~50 t/d at design speed

Burn cut

58%

less fuel per day

Container

1,915 underway at the last fix

Design speed

21.0 kn

Steaming now

13.3 kn

10–90th pct 9–17 kn

Main-engine burn

~38 t/d

~150 t/d at design speed

Burn cut

75%

less fuel per day

Gas (LNG/LPG)

118 underway at the last fix

Design speed

16.0 kn

Steaming now

13.7 kn

10–90th pct 9–17 kn

Main-engine burn

~60 t/d

~95 t/d at design speed

Burn cut

37%

less fuel per day