From HKBIA website:

Please find the response from the Marine Department in regards to the latest Covid-19 Restrictions:

Summary provided by Ince (HK):

Private boats have to comply with the two household rule, although the crew employed on those boats are exempt from that rule and can be onboard at the same time as the household(s) under the exemption prescribed at Cap. 599G.

But any pleasure vessels let for hire are currently banned from operation under Cap. 599F.