MB4 217a: Making a Mechitza on Shabbos and Mechitzos on Boats (362:3-5)

If a person made a mechitza on Shabbos intentionally

If a mechitza came down on Shabbos and one intentionally rebuilds it on Shabbos.

Carrying on a boat on Shabbos is permitted even if larger than a בית סאתיים because it is מוקף לדירה. Carrying on top of an overturned boat is permitted because of גוד אסיק מחיצתא.