Going back to my op. The primary purpose of a fireboat is not fighting ship fires, it’s as a mobile pump with an unlimited supply of water.
From the wiki page of my favorite boat, FDNY’s Fire Fighter (built by, naval architect William Francis Gibbs, the same man who built the United States):
“ Following the collapse of both buildings and resultant failure of the majority of the water mains serving lower Manhattan, Fire Fighter and the rest of the FDNY Marine Units became the sole source of water for firefighting efforts at Ground Zero, a duty which Fire Fighter maintained for a period of three weeks until sufficient repairs were completed on landside water mains to permit her release.”
1906 Earthquake:
The fire department responded, but soon discovered their biggest problem: The earthquake hadn’t just broken gas lines. It had also broken the water pipes feeding the neighborhood’s fire hydrants. As fire engines ferried in water from blocks away, and volunteers scooped up what water they could carry in paint buckets to throw on the fire, dispatchers summoned up a rarely-used resource
United States Navy fireboats USS Leslie, USS Fortune and USS Active were employed to provide the water to extinguish the fires triggered in the aftermath of the disastrous 1906 San Francisco earthquake.
That day changed the course of history for the San Francisco Fire Department. Despite having two completely separate water systems, each with its own reservoirs and fire hydrants, the department learned that metal pipes are no match for the force of a major earthquake — especially in the many parts of the city’s waterfront that are built on soft landfill and prone to liquefaction.
“In 1987, they were wondering why we still had fireboats, so they talked about decommissioning them at the time,” Amdahl said. But after 1989, “Everybody realized, yes, we do need fireboats, and we need more than just one.”
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I don’t have the reference in front of me but basically the majority of residents evacuated San Francisco via the docks but that was only possible because the fireboats came and extinguished the pier fires.
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Also of note in the head of the NRC’s Fukushima response team’s after action report Chuck Castro says the only viable solution to providing cooling water to reactors after earthquakes is with fireboats.