Hurtigruten is partly subsidized by the Norwegian government, as it is considered a public necessity, offering scheduled travel between points where public transportation might be scarce.

Thus, a number of cabins is supposed to be reserved for point to point travellers.

There even is a sort of "cabin guarantee" for walk-up travellers (1-5 PAX, four nights travel or less): one is guaranteed a cabin if one turns up on the quay at departure, unless 120 berths already are sold to point-to-point travellers. How this can be enforced, I don't know (especially how a customer could know that on a full ship how many passengers are point-to-point and how many are cruise passengers).

If booking far enough in advance, there usually is no problems in securing a cabin for a point-to-point traveller. I am going to Florø next week. Cabins are available on several dates, just not on the two when I wanted to travel. Still, availability is not that bad.

To find out which ship is sailing on which date, either go to the booking motor and do a booking. The ship's name will be dispayed with the price. Or go to the timetable, and click on the desired departure port, and put in the departure date.

Ed: you might have to go to the Norwegian version of the web page