KINGSTON, Jamaica — Dozens of doctors and nurses fanned out from a Chinese navy hospital ship to treat poor Jamaicans as part of a global humanitarian mission to portray China’s rapidly growing military as a responsible power.

The People’s Liberation Army’s 584-foot-long (178-meter-long) Peace Ark carries more than 100 medical volunteers who provide free surgery, CAT scans, eye care and other procedures.

The floating hospital was launched three years ago and is making its second foreign trip, the Chinese Embassy said. It is on a roughly 100-day journey around the Caribbean, where the United States is the largest investment source and military partner.

The aim of the operation, dubbed “Harmonious Mission,” is to soften the image of China’s 2.3 million-member military and boost its ties with other nations’ armed forces.

“It’s trying to use military powers in ways that are reassuring and not threatening,” said David M. Lampton, director of the China studies program at Johns Hopkins University in Baltimore, Maryland. “The Chinese have a strategy of simultaneously growing their hard power but using it in a soft way that’s reassuring and therefore doesn’t build a coalition of enemies against it.”

The Peace Ark has already visited Cuba and after Jamaica is scheduled to go to Trinidad and Tobago.

Chinese navy Lt. Cmdr. Chen Yong Peng, said: “Our team of medical staff is doing all kinds of surgeries and operations, nearly everything except organ transplants.

“China has had a long history of relations with Jamaica and other places in the Caribbean.”