The transfer of 25 million barrels between ships at sea would take roughly 3-6 months, depending on several factors:
Transfer Rate
Ship-to-ship (STS) transfers typically operate at 5,000-10,000 barrels per hour, with standard rates around 5,000-7,000 bbl/hr. This gives us:
At 5,000 bbl/hr: ~208 days (7 months of continuous pumping)
At 10,000 bbl/hr: ~104 days (3.5 months)
Key Variables Affecting Duration
Operational factors:
Oil type: Heavy crude pumps slower than light crude; viscosity is a major limiter
Pump capacity: Larger, newer vessels have more powerful systems
Temperature: Cold oil is more viscous; heating slows transfer slightly
Simultaneous operations: Whether cargo is being discharged from one ship while loading another (speeds things up)
Environmental factors:
Weather windows: Rough seas halt transfers; operations often pause during storms
Sea state: Even moderate waves can make connections unsafe; good weather required
Seasonal conditions: Some routes have better weather windows
Logistical time:
Connection setup: 4-8 hours
Safety checks and inspections
Disconnect and final cleanup: 2-4 hours
Real-World Context
A 25 million barrel transfer is enormous—equivalent to a quarter of the world's largest tankers' capacity. Most STS transfers are smaller. The operation would likely require:
High-capacity hoses and manifold systems
Dedicated safety personnel
Communication with maritime authorities
Multiple weather windows to complete
In practice, 4-6 months is a realistic estimate accounting for operational pauses and weather delays.