Mvweebles, I got the feeling they were searching for a “seller” to replace the 46.
I understand, the ER on the 47 was larger. How they distributed the +1 foot to the interior, I never learned.
In my opinion, the 47 and 46 bore little similarity to one another. PAE started with two models - the 46 and 62, both had very classic lines that obviously did well for them. Next came the N50 and subsequent N57, with more motoryacht lines to them. They were both relatively fast, and introduced concept of "Maintenance Strakes," bump-outs in the hull either side of the engine to provide standing headroom. Stroke of genius in my opinion. My understanding is the N57, with it's 'chariot flybridge' located slightly behind the pilothouse roof, similar to KK42s, was due to limited height at the manufacturing facility. The N40 was introduced around this time with the fanfare of the ATW event, which was admittedly impressive. I have to say, I really, really wanted to dislike the N40 as it was traitorous compared to the N46/N62 classic lines. But the N40 was impressive - the space in the ER alone was amazing: somewhere I have a picture with a dozen people in the engine room at a Trawler Fest.
In the early 2000's, PAE was in high-gear with larger, taller boats (the N55 for example). They moved manufacturing to a larger yard. From my simple observation, many of the fittings were changed and quality reduced somewhat. The doors were painted aluminum, which oxidized and bubbled quickly. The boat design appeared to increased A/B ratio and rely on stabilization more heavily (in a modest seaway, the N40, for example, rides fairly well without stabilization - the N47....not so much). I expect the N43 would be an extension of the N40 with a larger PH and a helm chair.
After about 2005, I really lost track of boats, and PAE as I returned to corporate life, which was lucky for me - the 2008 recession would have left me hugely exposed as a delivery captain for boats which were not selling. I have no opinion on Nordhavn's of more modern vintage.
If you read Leishman's re-write of Voyaging Under Power, you will find very quiet clues to PAE's learning curve on the N46. Originally, they wanted the 1000 gallon fuel tank midships for balance, but decided to move it aft with saddle tanks to provide more living space. Midway through the production run, they went to fiberglass tanks and distributed them more forward. Leishman mentions that if they were to do the design over, he would reduce the rake of the bow and increase the waterline. I think he's spot-on: would reduce reserve buoyancy in the bow and balance the boat a bit to prevent hobby-horsing in a head sea. I delivered a half dozen N46's north from Dana Point CA against prevailing seas to the PNW, including one of the very last ones built. Fully loaded, the N46 squats a bit in the stern, and is a bit bouncy in the bow in headseas - I fully preferred running with half-load of fuel when headed north to flatten the ride.
At any rate, my heart still lusts after the N46/N62. But the N57 is my favorite, though I am not keen on the bulbous bow due to slap/noise in a seaway (again, my fate as a delivery skipper at the time). But is a relatively fast boat. I delivered one from Dana Point to Ft Lauderdale - about 4500 nms in 25-days and burned 3000 gallons......and averaged 9.3 kts (excluding Canal time).
Boats are heavily opinion-driven. All I can tell you is I spent a lot of time on Nordhavns under mostly uncomfortable conditions - headseas heading north along the very long California coast to escape sales tax. They are all very good boats from a company that has earned respect not just an adroit marketer, but from people who test their boats and make adjustments. Despite feeling betrayed by the design of the N40, it was a fantastic boat. Thus my strong inclination on the N43. The N47 did not similarly impress me thus my statement that if similar condition examples were at the same dock and I had to chose one, no question for me, would be the N43.