The Rainier class was intended to replace Navy harbor tugs which were built between 1964 and 1975,[2] which by the 2020s had reached the end of their service life.

The design is an evolution of the YT-802 Valiant class, which is, in turn, an evolution of the Z-tech 6000 commercial tug design produced by Robert Allen Ltd.[3] Contracts for the construction of the first four ships in the class were awarded to Dakota Creek Industries of Anacortes, Washington on 13 July 2018.

[10] Electrical power aboard is supplied by two John Deere 6068AFM85 generators, each capable of producing 154 Kw.

[9] The tugs have two fire-fighting monitors mounted forward of the wheelhouse, and a pump that will supply them with 2,000 US gallons (7,600 L) per minute.

[9] The class has a complex fendering system that is capable of pushing both high-sided ships such as aircraft carriers, and the rounded hulls of submarines.

Nonetheless, local authorities have named all of the Rainier-class tugs after mountain peaks in their operating areas.