Tanker RFA Black Rover trails a thick fuel line into the South Atlantic as she practises keeping HMS Iron Duke topped up on patrol.
Off Africa’s western seaboard between Walvis Bay in Namibia and Cape Town, the veteran oiler carried out a dry run of a stern replenishment at sea – making all the connections with the Portsmouth-based frigate, without actually pumping black gold from its tanks into the warship’s.
The two vessels have been working in tandem all the way down Africa’s west coast during a mix of flag-flying visits and exercises with local military and law enforcement agencies.
At a regular cruising speed of about 11 knots, a Type 23’s frigates engines will guzzle 600 tonnes of diesel every 30 days – and those 600 tonnes of fuel will carry it more than 9,000 miles (almost enough to take a ship from Portsmouth to Singapore).
Therefore her tanks shouldn’t need re-filling too often – but in reality the tanks of RN vessels are kept relatively full all the time to ensure they’re ready to respond to the unexpected.