The deliberate grounding and refloating of a cargo ship off the coast of England underlines the increasing complexity and cost of marine salvage operations.

Refloating the Hoegh Osaka, which was carrying 1,400 luxury automobiles when it developed a severe list in January just outside the port of Southampton, England, followed several large marine losses in recent years, such as the grounding of the Costa Concordia cruise ship and the sinking of the MV Rena.

The events have highlighted the delicate nature of salvage operations, the extensive costs involved and the need for highly skilled salvors, experts say.

The Hoegh Osaka developed the list shortly after leaving port, and its pilot deliberately grounded the ship near the Isle of Wight to avoid greater damage. The ship was towed back into port at Southampton in late January.

The situation exemplifies the increasing complexity of salvage operations and why costs are rising, said Andrew Kinsey, a former ship's captain and now senior risk consultant of marine at Allianz Global Corporate & Specialty in New York.

Although the ship was saved, steps had to be taken to ensure it emitted no pollution and it did not run aground somewhere else, he said.

Large salvage operations such as the Costa Concordia off the coast of Italy in 2012 “really focused the mind,” said Sam Kendall-Marsden, syndicate director at the Standard P&I Club in London, the lead club on the protection and indemnity coverage for the ship.

The highly complex salvage was carried out under great scrutiny from Italian authorities keen to avoid pollution, he said.

In the wake of that and other large salvage and wreck removal operations, the International Group of P&I Clubs, the world's 13 largest P&I clubs, produced an internal report.

The report, Mr. Kendall-Marsen said, found key factors influencing the complexity and cost of salvage operations primarily were local authorities' level of involvement, the location of the event, contractual considerations and bunker removal requirements, or the removal of fuel powering ships.

“No one should be surprised to see a high level of involvement” by local authorities if a ship runs aground or sinks, he said.

Another challenge facing salvage crews is finding someplace to move the stricken vessels, Mr. Kinsey said, which Mr. Kendall-Marsden said was an issue for the Costa Concordia.

In addition, removing and finding a suitable place to store containers from a stricken vessel also is a key concern.

“Megaships,” some of which can hold up to 19,000 20-foot-unit equivalent containers, also may have difficulty finding a port large enough to accommodate them, Mr. Kinsey said.