Eruvin 42

Why is a boat different?

Would you love to take a boat trip but wonder if it’s OK to continue travel on Shabbat? The rabbis on today’s daf had that exact same question.

It begins with an incident recorded in a mishnah on yesterday’s page in which several sages were on a boat on Shabbat. The mishnah tells us that two of them, Rabbi Gamliel and Rabbi Elazar ben Azaria, walked around the entire boat on Shabbat, but that two others, Rabbi Akivah and Rabbi Yehoshua, did not, restricting their movements to an area of four cubits. In Jewish law, four cubits is the area of someone’s personal space, so Rabbi Akivah and Rabbi Yehoshua were effectively saying a person should not move at all beyond their personal area on a boat on Shabbat.

On today’s daf, the Gemara brings this story to bear on a question we’ve been dealing with for many pages now — how far is one permitted to travel on Shabbat? As we’ve seen, it is forbidden to travel more than 2,000 cubits from your residence on Shabbat. On today’s daf, the rabbis entertain the question of whether this limit also applies if someone is traveling on a boat. A boat is clearly going to travel more than 2,000 cubits. However the Talmud tells us that this is nevertheless permitted.


Rav said: The halakha is in accordance with the opinion of Rabban Gamliel with regard to a pen, a stable, and a boat. And Shmuel said: The halakha is in accordance with the opinion of Rabban Gamliel with regard to a boat, but not with regard to a stable or a pen.


Rav and Shmuel disagree about whether the precedent set by Rabban Gamliel in the mishnah applies in animal enclosures like pens and stables. But they agree that his practice of walking freely on a boat on Shabbat is the law. Why is a boat different?

Rabba explains:


This is since he acquired his place of residence within the partitions of the boat while it was still day, in which case it is reasonable to say that the entire boat is considered as if it is only four cubits.


In other words, according to Rabba a traveler on a boat effectively turns the entire boat into their own four-cubit space. By doing so, they can move about the entire boat without fear of transgressing a Shabbat violation.

The Gemara concludes that not only can a person move about a boat freely on Shabbat, but they can carry within that space as well. Which is very good news for Jewish travelers that would like to go on a cruise.

Read all of Eruvin 42 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on September 20, 2020. If you are interested in receiving the newsletter, sign up here.

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