I found this about the Westerdam on Cruise deck plans. I wish I knew which balconies!
The ship last drydock was in Jan 2020.
Most modern cruise ships need to be dry docked for inspection, maintenance and class surveys every five years and once they reach 15 years of age they need to be dry docked at least twice within a five-year period. Dry docks typically last up to 14 days at a cost of up to $2 million per day and involve regular maintenance including hull cleaning, exterior painting of the structure, inspection of pipes, restoration of exterior deck flooring, and installation of enhanced HVAC filter systems
This ship underwent a major upgrade in 2007. Some of the decks were extended length wise by 130 feet. 34 new passenger cabins were added to decks 6, 7 and 8. As a result some aft balconies were made narrower. Some other changes included expanding the Sea View Pool area on deck 9, Explorations Cafe replaced the Oak Room, Windstar Cafe was removed and new shops were added.During drydock Apr 14 to 26, 2017 added Casino Bar and Billboard Onboard in place of Piano Bar and Sports Bar. Replaced Northern Lights Disco with Gallery Bar. Transformied Explorers Lounge into Lincoln Center Stage. Added 18 balcony staterooms and 7 inside staterooms to deck 10 forward. Added Retreat with Cabannas to Deck 11.