Everything you need to know about the hospital ship heading to New York—and the ones that might replace it

Typically, hospital ships are large. The two currently in service, USNS Mercy (T-AH 19) and USNS Comfort (T-AH 20), are behemoths of the ocean, sporting designs based on supertankers.

Just how big are these vessels? According to Military Sealift Command, the Mercy and Comfort are almost 900 feet long, displace 69,552 tons, and have over 1,000 beds for wounded troops. They were purchased and converted in the 1980s and one is based on each coast of the United States.

USNS Comfort (T-AH 20)

(US Navy)

Unfortunately, time wins out eventually, and these ships are getting up there in age — both started life as a supertanker more than four decades ago and have been used as medical ships for the last 30. Not only are these ships old, they're also fairly alone in military service. With just two hospital ships in service, the military runs the risk of entering something similar to the Coast Guard's heavy icebreaker situation. The Mercy and Comfort are also slow — they can reach a top speed of 17 knots. What did you expect? Supertankers aren't known for their speed.

The Military Sealift Command's joint high-speed vessel USNS Spearhead (JHSV 1) patrols the Atlantic Ocean as part of the Africa Maritime Law Enforcement Partnership.

(U.S. Navy photo by Mass Communication Specialist 2nd Class Kenan O'Connor)

So, it should come as no surprise that the Navy wants to replace them. But how? Well, at SeaAirSpace 2018 in National Harbor, Maryland, Austal presented an interesting idea. This is the company responsible for the Independence-class littoral combat ships and the Spearhead-class expeditionary fast transports. Austal thinks a modified version of the latter could do the job.

A model of Austal's proposal for a new hospital ship based on the Spearhead-class expeditionary fast transports.

(Harold Hutchison)

Now, the modified Spearhead has a lot less capacity (maybe 6 critical-care beds and another 12 hospital beds), but it is faster and there would likely be more than two. As a hospital ship, it remains unarmed — because nobody, in theory, is to shoot at it (doesn't always work in practice). The model at SeaAirSpace 2018 was, like Mercy and Comfort, painted white and marked with the Red Cross.

It remains to be seen if these small, fast, hospital ships will end up on the high seas.