Chapter 248: Traveling by Ship over Shabbos
1. Traveling on a ship from before Shabbos including Shabbos:
There are many possible Shabbos prohibitions that can be involved in traveling on a ship over Shabbos. This includes the following:
- Loss of Oneg Shabbos: One who travels on ship within 3 days before Shabbos, loses his Oneg Shabbos if he is traveling a long trip over salty waters. If however he is traveling for a short trip or is traveling over a river, then there is no loss of Oneg Shabbos. Likewise when traveling prior to 3 days before Shabbos there is no loss of Oneg Shabbos. If one is traveling for a Mitzvah purpose then he may do so even over salty waters.
- Techum Shabbos: If one knows that the sea level is less than 10 handbreadths above ground in the area that one is to be traveling in, then it is forbidden for one to enter the ship within 3 days before Shabbos due to the prohibition of Techumin. If however one is in doubt then it is permitted. If one will be staying in the area of the ship that is above 10 handbreadths from ground, such as that part of the ship is above 10 while another is within 10, then there are opinions which are lenient and in a time of need may be relied upon. When traveling for a Mitzvah purpose one may do so even on Erev Shabbos, even if he knows that the ship will be traveling within 10 handbreadths, as long as he tells the ship crew to rest the ship on Shabbos.
- Chilul Shabbos due to Pikuach Nefesh: If one knows for certain that he will need to desecrate Shabbos due to Pikuach Nefesh on the ship then it is forbidden for one to travel within three days before Shabbos. However for the sake of a Mitzvah it is allowed to travel even within 3 days before Shabbos if there involves Pikuach Nefesh for the ship to stop on Shabbos, however if there is no Pikuach Nefesh involved for the ship to stop on Shabbos then there is no allowance for one to enter the ship [even prior to three days before Shabbos].
If one is in mere doubt as to whether he will be required to desecrate Shabbos, he may travel even within 3 days.
- Amirah Lenachriy: If the gentile ship navigator is navigating the ship [or do any Melcha which is not needed for Pekiuach Nefesh] on behalf of the Jew, then it is forbidden for one to enter the ship within 3 days before Shabbos due to Amira Lenachri. This however can only apply if majority of the ships travelers are Jewish. It is permitted to travel in all cases for the sake of a Mitzvah.
- The definition of the need of a Mitzvah: There are opinions which say that included in the definition of the need of a Mitzvah is even if one is traveling to visit a friend or for business. Those which follow this opinion are not to be protested against doing so.
For the sake of a Mitzvah: Is always permitted to travel even within 3 days before Shabbos, even if gentile is doing so for the sake of the Jew, and one will need to desecrate Shabbos due to Pikuach Nefesh, and one will be traveling over salty waters, and one will be traveling above 10 Tefach.
Not for the sake of a Mitzvah: Is only permitted if traveling prior to three days before Shabbos [for a needed purpose], or within three days before Shabbos, but will be traveling in a river, and is unsure whether the ship is within 10 Tefach from ground of sea, and there is no need to do Chilul Shabbos, and the majority of the passengers are Jewish.
May one travel on an Israeli ship within 3 days before Shabbos if he will be traveling over Shabbos?
No as majority of the travelers are Jewish, and thus the Chilul Shabbos is considered done on behalf of the Jew. Furthermore there are many Melachos which are done not for the sake of Pekiuach Nefesh, and these of course are also being done for the sake of the Jewish travelers.
May one get a surgery within 3 days before Shabbos?
It is forbidden to arrange a surgery to be done within 3 days before Shabbos, as this causes one to not have Oneg Shabbos, as well as to desecrate Shabbos.
May a woman receive a birth stimulant shot within three days before Shabbos?
This is to be avoided for reasons stated above.
2. Entering a ship on Shabbos:
It is forbidden for one to enter a ship on Shabbos due to a decree that one may create something to help save him. However there are opinions which permit this if one was on the ship throughout the entire twilight of Erev Shabbos, so long as none of the above mention prohibitions are in effect.
3. Traveling by caravan over Shabbos:
First Opinion: If one knows that he will be required to desecrate Shabbos on his journey then it is forbidden for him to leave even on Sunday, and even for the sake of a Mitzvah.
Second Opinion: It is only forbidden to travel when one knows he will have to desecrate Shabbos if it is within three days before Shabbos, and it is not being done for the sake of a Mitzvah.
The Final Ruling: One is to be stringent, although those which are lenient have upon whom to rely. However one should not be lenient in this case regarding the definition of “a Mitzvah purpose”.
May one travel on a train on Shabbos?
Doing so is forbidden even if majority of the travelers are gentiles, due to that it nullifies Oneg Shabbos, and even prior to 3 days before Shabbos it is forbidden being that it transgresses the Issur Techumin.
May one travel on a plane over Shabbos?
No, due to the above mentioned reasons.
May one ride a bike on Shabbos?
 Kitzur Hilchos Shabbos
 However for mere touring the Tzemach Tzedek prohibits, if doing so will involve any of the above mentioned prohibitions.
 Shaar Halacha Uminhag 129; Minchas Yitzchak 2/106; Igros Moshe 1/92
 Piskeiy Teshuvos 248/4
 Chasam Sofer 97
 However see Lekutei Sichos 28 p. 127 footnote 15 that based on the logic of the Chasam Sofer that by a caravan which moves on its own, as does a train, then there is no problem of Techumin as Admur rules that today Techumin is only Rabbinical since we do not have a Reshus Harabim, and a Rabbinical doubt we are lenient by. Nontheless the Rebbe concludes that the Achronim have ruled that it is forbidden.
 Minchas Yitzchak 2/106
 These include:
- One may come to fix the bike in case of it breaking
- One may come to ride outside the Techum
- It is demeaning of the Shabbos day
 Beir Moshe 6/16 in name of many Poskim.
However the Rav Paolim  allowed riding a bicycle, although in the Teshuvas Yaskil Avdi 3/19 it is brought that he retracted his ruling.
 Beir Moshe ibid