I served my National service in the Norwegian Navy in 1965-66 as Coxswain on the MTBs KNM Tjeld (P343) and later KNM Gribb (PT388)
The US Navy bought some of these type of boats for use in Vietnam, first for clandestine operation by CIA, before the official US entry into the war in 1964. Officially operated by the South Vietnamese Navy, but with Norwegian ex Naval Officers and US Marines as “advisers” on board.
Two of these boats were involved in the Gulf of Tonkin incident that was the “excuse” to get officially into the war in the first place.
Of the US boat 14 were built in Norway and 6 in US. All were either sunk, or stricken of the register by 1981, but there are apparently a few still in existance somewhere: https://en.wikipedia.org/wiki/United_States_Nasty-class_patrol_boat
I saw some of them in Vietnam in 1967-68, but without the torpedo tubes, but with heavy machine guns mounted “all over the place”.
The ones that operated in the Mekong had sand bags to protect the superstructure.
I found a website by some American veterans and/or Naval enthusiasts who try to keep track of what became of these boats, mainly the US ones, but also a bit about the Norwegian boats: http://www.ptfnasty.com/
Are there anybody here on the forum that know anything about the status of the PTFs, or has any background stories about these boats??