Embarking a ship on shabbat

Question

Ignoring questions of carrying, activating electronic devices, etc. (assuming these can be overcome), why is it not permissible to embark on a ship which is manned by non-Jews and which will sail on shabbat?

Is it any different from getting on a bus being operated by a non-Jewish driver, to whom one has handed one's ticket before Shabbat (which I think is permissible - again, ignoring marit ayin)?

Answer 1

DailyHalacha provides one reason that embarking on a boat is different from boarding a bus which is that you get sea-sick on many boats - not on buses. Since they provide one minority opinion which differs, it is a question best answered by your rav.

Hazal enacted this prohibition forbidding boarding a ship within a few days of Shabbat because doing so will likely interfere with one's "Oneg Shabbat" – the enjoyment of Shabbat. It often takes several days to accustom oneself to sea travel and overcome seasickness, and so the Sages forbade boarding a ship too close to Shabbat in order to ensure that one will be comfortable and at ease on Shabbat.

Interestingly, Rabbi Moshe Halevi (Israel, 1961-2001), in his work Menuhat Ahava (1:2), raises the possibility that this enactment of Hazal might not apply nowadays, when boats are very large and stable. Furthermore, most people who travel on cruises are accustomed to sea travel and thus do not become seasick. Nevertheless, the vast majority of Halachic authorities dispute this position and forbid boarding a ship after Tuesday (or Wednesday), unless one travels for the purpose of performing a Misva.

See here for more details and the views of the Rif and Rambam - aligned with the above.

Answer 2

The other answers touched on this, but let me just spell it out more -- even if I'm not combusting anything, doing anything electronic, or carrying anything, there is a prohibition called Techum Shabbos -- (lit. "the domain"). I am prohibited from walking ~1 mile past the limits of the city where I was located on Friday night. If you are a good walker and/or live near the edge of your city, you could violate Techum just by walking a lot!

So a bus all over Brooklyn would remain within the city limits and thus (in and of itself) within Techum. (A Greyhound bus from St. Louis to Chicago, on the other hand, would violate Techum.) Embarking on almost any ship is bound to violate Techum, unless it is staying very, very close to the shoreline of an inhabited area the whole time (e.g. a yacht circumnavigating Manhattan).

(For this reason, if a ship was far out from land at dusk on Friday, then arrives into port on Shabbos morning, the "home city" of the passengers is now the ship, and they are prohibited from disembarking on Shabbos as that also would be a case of breaking Techum.)

There are other issues, as other answers referenced -- seasickness; the likelihood someone would need to save your life if something went wrong -- but the clear difference between bus and boat (in most cases) is Techum.

Answer 3

The Mishna Brura Orach Chaim 248 which discusses all of the questioners problems.

והנה המחבר אף שנמשך בס"ב אחר הרי"ף שהעתיק פירושו מ"מ גם הוא ס"ל כהפוסקים דקודם ג' ימים שרי אף במקום שיצטרך אח"כ לבוא לידי חילול שבת ע"י מלאכה וכמ"ש ס"ד [ועיין במה שכתבנו שם] אלא דס"ל דאף אי לא היה בו שום חשש מלאכה ותחומין [כגון שהיא כולה של א"י דכשנעשה בה מלאכה מסתמא אדעתיה דא"י נעשה וגם היא במקום שעמוק יותר מעשרה טפחים דאין בזה משום איסור תחומין להרבה פוסקים וכדלקמן בסימן ת"ד ע"ש] אפ"ה אסור משום ביטול עונג שבת לחוד

The Shulchan Aruch holds that one can travel more than 3 days before Shabbos on a boat even though he might be forced to save his life by doing a Melacha as he is used to the rocking of the boat. However from Wednesday onward one cannot travel on a boat (unless for the sake of a Mitzva) because he is distressed by the jerking of the boat.
Even though
1. There is no issue of Techumin (travelling 2000 amos beyond city borders) when the water is 10 tefachim below the shore
2. There is no issue of amira leakum (getile performig a melacha on a Jews behalf) when there is a majority gentile passengers on the boat.
One must be relaxed on shabbos (Oneg Shabbos) that one feels strained when on a boat (it sways about, one is nervous it might sink in a storm).

These 3 potential issues mentioned apply when travelling on a bus not for the sake of a Mitzva (see Shulchan Aruch Orach Chaim 248,1):

1. one is not relaxed (which lurches forward and one is not settled when travelling).
2. One could be travelling out of the techum of city which is completely forbidden.
3. the gentile is doing a melacha directly for a Jew if he stops at a bus stop for the Jew to get off(unless most people getting off are Gentiles.