How the nugget came about
Art Piver was banging around in different boats in the late 50s. He made cats and then did some tris. The first good one was a 16ft version called Frolic. It was brutally simple but in those days there were no Hobie cats and so it must have been one of the first US boats to accelerate and cartwheel and do all the things that are normal now in small cats.
He then designed a bigger version for a guy called Carelton Eugene in late 1958. It, like the Frolic, was designed as a daysailer. It had a cockpit in the middle of the boat as shown in the drawings above and was the Nugget Mk1 (sort of). (The floats on early Piver tris were not the flat deck shapes we see now. They were a trapezoid shape with a veed deck - very hard to walk on)
It didn't take long before someone put a cabin on. Jim Brown, legendary designer of the Searunner tris, had made a Frolic (he is mentioned in Piver's first book and writes about this time in The case for the cruising trimaran) and decided to make a Nugget too this time with a small cuddy cabin. He took it to Mexico and then later on Piver took an even bigger design across the US by rickety trailer and truck and then on to the UK. This Nimble had the trapezoid floats too.
I am not sure when the flat decks appeared but they were on Piver's next boat - Lodestar which he sailed across the Pacific in about 1962. In his 2nd book Piver talks about a Nugget sailor who was surfer with heaps of mates up the front trying to pitchpole it without success. I think that was a flat deck and cabin version. The green Nugget that I think may have been converted into Damies boat was the version in the second photo - cockpit in the centre. Good for a crew so that the stern doesn't squat. I will check in the book over the weekend.