Several years ago the Chinese navy developed what appeared to be a new stealthy trimaran fast attack craft (FAC) design. This small (under a thousand tons) ship was at first believed to be a test ship that could later evolve into a larger more versatile platform, similar to the U.S. Littoral Combat Ship (LCS) program. But this never happened, and while a few ships like this were built, they never showed up as warships. It turns out that military developments of this design were quietly abandoned and at least one of them was equipped with rescue boats and put to work doing search and rescue duty along the northern coast as "North Rescue 143".
When this design first showed up in China it was thought that the use of an advanced trimaran hull design demonstrated that the Chinese were able to incorporate advanced European and Australian fast ferry technology a bit faster than the U.S., as American programs to use these ships and this hull technology was then only in the design and experiment stage. While the U.S. did use some Australian designed fast ferries in the 2003 Iraq invasion, the U.S. was not yet building such ships itself. The trimaran hull configuration confers greater high speed capability in heavy weather, while providing a large deck space for multiple uses.
What might have halted Chinese work in this area was a shift in the last decade away from a coastal fleet (with lots of small, fast missile armed boats) to a high seas fleet with larger ships (like their recently launched carrier and new classes of large destroyers). Then again, turning their trimaran ship into "North Rescue 143" may simply be a way to see how the ship deals with some pretty rough waters over an extended period.