While RFA Mounts Bay continues her work in the Caribbean following Hurricane Dorian, her sister ship has been visiting London.
RFA Lyme Bay is in the English capital for London International Shipping Week and will be moored up near the Old Royal Naval College.
The Royal Fleet Auxiliary (RFA) itself provides support to the Royal Navy during deployments and operations.
It is staffed by merchant sailors and is the civilian branch of the Naval service.
As Mounts Bay has proved in the Bahamas in landing personnel and aid, the RFA's vessels are versatile.
Lyme Bay is one of three Bay-class RFA vessels. The class allows personnel to move from ship to shore using onboard Landing Craft Vehicle Personnel and Landing Craft Utility vessels.
They are also armed with an automated small calibre gun to defend against missiles and explosives.
It is a ship able to handle vast stores, get aid ashore quickly and in quantity, provide power to stricken communities and be the command centre for an amphibious force.
Lyme Bay also contains a large cargo area with a special feature.
"We have the ability to dock the ship down - so flood the back of the ship, and then we can either take in rafts, small boats, etc, that we can loads vehicles on to, to then go off to the various ravaged islands to land those vehicles ashore," Lyme Bay's executive officer, Chief Officer Pierre Wyatt, explains.
"We also have a large flight deck on the back end, able to carry a Chinook helicopter, and a huge amount of accommodation for troops - anything up to 350 troops we can support."
In terms of capacity, the vessel can accommodate up to 150 light trucks or 24 Challenger tanks. Crucially, there are 1,200 linear yards of space for humanitarian aid.
The ship has a 16-knot top speed and a range of 10,000-miles.
Lyme Bay's diesel-electric propulsion system can be put to a different use: "For things like disaster relief, it allows us to act as a mini-power station and feed shore facilities," marine engineer, Third Officer David Taylor says.
"We can feed a grid on an island to provide shore power for their hospitals, police stations, etc."
The ship can generate 12 megawatts, enough for several hundred homes.
Lyme Bay also contains an Amphibious Ops Room - this is where embarked forces, like Royal Marines, can plan and communicate their operations.
It is the only RFA vessel with the capability.
"It's mainly a command planning area, but each section's got its own job," says Second Officer John Wainman.
"You have information management, there's intelligence gathering in one area."
RFA Lyme Bay will be moored in Greenwich for London International Shipping Week.