Well I guess the brochure on my 1973 Ketch was correct....it is officially a Motor Sailer....
I'll not be able to help much either: I guess all of us would as an example agree that the Fishers and there ilk are motorsailers and that Open-50s are yachts, but beyond that it gets increasingly blurry and our own yacht's a fine example:
We sail 35' Trident 'Challenger' a stern
cockpit sloop, originally built with an engine of about 30hp in it and I've never seen it referred to as anything other than a 'yacht'.
Trident
Marine also built a 35' 'Warrior' a centre
cockpit sloop, originally fitted with an engine of about 60hp and I would say that
references to this model are 60/40 in describing it as a yacht or a motorsailor; I suspect because of the big engine?.
During the same period, Trident
Marine also built a few 35' 'Voyagers' this being a stern-cockpit pilot-house sloop, originally fitted with an engine of about 40hp; I would say that
references to this model are 60/40 in describing it as a motorsailor rather than a yacht, this being on the basis of its pilot house.
Now all three vessels have exactly the same hull/underwater profile, similar weight and whilst I believe that the Voyager's
mast is a touch shorter, I think this is due only to the deck-moulding profile and the sail area of all three's remains identical. Whilst none of them could be described as 'fast', they're all very tough and capable ocean crossers (under sail) If I had to choose the best 'sailing' yacht amongst them, I'd probably plump for the Warrior, just shading the Challenger and then the Voyager, with accommodation in the reverse order - though bigger steps between the three.
Honestly, I really don't know; the Challenger's definitely a 'yacht' and with a smaller (why the 60hp job?) the Warrior would always be so thought to, but if they'd put the big motor in the Voyager, I think everyone would've called that a motorsailor, due to its more palatial accommodation?