Sank a few days ago.

Thank you all for the ID.

Hi David, your picture represents the old ferry M / F Grønsund (ex Gammelør) which was built in Nykøbing Mors / Denmark in 1967 and in 2001-2003 was converted into a restaurant ship and which still functions as such in Copenhagen.

At the bottom of this link you will find an old picture of the ferry.
https://sites.google.com/view/bogoehistorie/bog%C3%B8-arbejder/transport/f%C3%A6rger#h.p_uKCr2wyOSqY8

And here a link to the "Færgen Gronsund" website
http://www.gronsund.dk/kalender.html

Best Regards
Bendt

It's my impression that this is a party venue, weddings, family reunions, that sort of thing, rather than a housboat. I have been a guest there once, but I have no info abaout a name, sorry.

This might help but only in Danish:
http://www.christianshavnernet.dk/Christianshavn/Kvadrant/Husbaade.html

The inscription on the life-ring looks like "Trygg-Hansa" to me. Trygg-Hansa is a danish insurance company. Possibly we have to puzzle a little further.
Brgds,
Stefan

There is something written on an almost hidden white life-saver ending with HANSA in the recess after "the left tower of the castle".