I know power bars or anything with surge protectors are not allowed on cruises and will be confiscated. How about a travel adapter like this one?
https://www.amazon.ca/SAUNORCH-Universal-International-Worldwide-Electrical/dp/B07B4GPJ56/ref=mp_s_a_1_1_sspa?keywords=travel+adapter&qid=1555086212&s=gateway&sr=8-1-spons&psc=1
it doesn’t have surge protection, but does have “built in safety shutters and fuse”
thanks!