The repo cruises are called "ocean cruises" and sometimes it's "free" with the preceding or following cruise. One such (during COVID) was Ushuaia to Lisbon or v-v, non-stop following an Antarctic cruise. I do see there are none on offer currently. AFAIK, crewing on these are full. The sailings I was on was Papeete to Honolulu with over 200 (IIRC) so less than a full ship. The following was a non-stop Honolulu to Maizuru ("Kyoto") with what appeared to be a full crew but just ~70 pax. The preceding cruises were Ushuaia to Hanga Roa (a difficult stop for most cruise ships to make) and Hanga Roa to Papeete. The Honolulu-Maizuru cruise was a complimentary ocean voyage and also offered no single supplement. We did not get the free voyage because our Papeete - Honolulu fare wasn't regular price, and it was cheaper to book it the way we did anyway. Due to personnel disagreement, we lost the chef de cuisine a few days after leaving Papeete. The sous chef stepped into the role but we lost him in Honolulu. The head line chef (a Filipino) stepped into the sous chef role. Food was competent but a but repetitive as a result. IRC, there is 1 boulanger (baker), and a chef and assistant patissiere hence the great baking and desserts.

The sister ships are good enough to do the Northwest passage and have done so several times, but have also aborted the crossing due to ice conditions. One even switched from the Northeast Passage to the NW passage ~3 years ago. Bargain for those who booked it before the switch.

The Explorers are 11m shorter but also 1C icebreaker rating which is the same as the sisters.

Abele sounds vaguely familiar but it wasn't 1757 (whatever that is).