Chapter 74 : Laws of Embarking on a Ship

§1

You may not board a sea-going vessel less than three days before Shabbos; that is from Wednesday on, it is forbidden. But if you are going to perform mitzvah, you may embark even on Friday.

§2

[If the boat is to sail] on rivers you may embark for Friday, provided that a Jew need not perform melachah on Shabbos. And even if animals pull the boat, it is permitted.

§3

(In cases) where it is permitted to board ship on Friday, and you boarded the ship on Friday and remained there until dark, even though you went home and remained overnight at home, you are permitted back on board ship on Shabbos, provided the ship does not make the trip exclusively for Jewish passengers. However, since you were in your house on Shabbos, you established shevisah [residence] in your house, therefore, if the boat sails more than the techum Shabbos and reached land on Shabbos, you are permitted to walk only four amohs, but it is forbidden to walk more than that from the landing. See chapter 95.

§4

It is permitted to board a ship on Shabbos in order to pray with a minyan of ten, or for the sake of another mitzvah, provided the ship is making the trip for others as well. However, you should try to board the ship on Friday while it is yet day and remain there till nightfall, after which you may return to your home, and come back to the boat on Shabbos. But if the vessel makes the trip only for the sake of a Jew, it is not permitted.