Arthur Piver

Arthur Piver (1910–1968; pronounced like "diver") was a pioneering American multihull designer, often called the "father of the modern trimaran" (or sometimes modern multihull). A World War II pilot, amateur sailor, author, printshop owner, and self-taught boatbuilder based in Mill Valley on San Francisco Bay, California, he popularized affordable, amateur-built cruising trimarans in the late 1950s and 1960s.
Piver's designs emphasized simple, plywood/fiberglass construction using everyday materials (lumberyard and hardware store supplies), making ocean-capable multihulls accessible to non-professionals. He started small and scaled up rapidly:

His first trimaran was the 16 ft Frolic (launched ~1957–1958), a basic day-sailer prototype.
Followed by the 21–25 ft Nugget series (e.g., 1958 onward), capable of coastal/offshore work.
The breakthrough Nimble 30 (30 ft, 1960) — he trucked it across the US, assembled it, and made the first recorded North Atlantic trimaran crossing (from Massachusetts to England via the Azores), proving the concept's seaworthiness.
Other notable designs: Lodestar 35 (his personal Pacific cruiser, sailed San Francisco to New Zealand in 1961–1962), Victress 40 (used in famous races like the 1968–69 Golden Globe, e.g., by Nigel Tetley), Stiletto 33, Pi series (up to 65 ft), AA series (Advanced Amateur, including the AA-17 you asked about earlier), Allegro, Empress, Encore, and larger ones like 64 ft charter versions built in England.

His plans sold widely through ads in magazines like Popular Mechanics, sparking a home-build boom — thousands of Piver trimarans were constructed worldwide by amateurs and pros (some via licensed builders like Cox Marine in the UK). Features included V-shaped amas (floats) for stability, lift, and a comfortable ride; demountable beams for trailering; and lightweight performance that allowed surfing in big seas.