Dateline

This article was reproduced with permission from the STAR-K.
From the article "Don't Miss the Boat:
Halachic Guidelines of Kosher Cruises" by
Rabbi Zvi Goldberg, Star-K Kashrus Administrator


The International Date Line is, by convention, 180 degrees from Greenwich, England. At noon on Monday on the Eastern side of the dateline it is noon on Tuesday on the Western side. While halacha also recognizes the need for a dateline, the majority of poskim do not accept the International Dateline as the halachic dateline.21 Issues related to the International Dateline are extremely complex. We present several examples here to suggest questions to pose to one's Rav.

As an illustration, let us look at Alaska, a popular cruise destination. According to Rav Yechiel Michel Tucazinsky, author of the Gesher Hachaim, the dateline is 144.8°W, exactly 180° from Jerusalem. A cruise to Juneau would not present a problem. However, according to Rav Tucazinsky's opinion, if the cruise sails westward towards Valdez, Anchorage, Kodiak or the Aleutian Islands, the dateline has been crossed (at a line that corresponds approximately to Valdez). Rav Heinemann, shlit"a, holds that in deference to Rav Tucazinsky's opinion, one should observe dinei deoraisa (prohibitions of the Torah) on Friday, since Rav Tucazinsky considers it as Shabbos. Therefore, actions such as writing or turning on lights are prohibited. However, since Rav Tucazinsky's opinion is a minority one, Rabbinic prohibitions, such as shopping or handling muktzah, are permissible on that day. Furthermore, using a shinui, unusual manner, to perform a Biblically proscribed violation of Shabbos or doing so through the action of a non-Jew, would be permitted on Friday. Shabbos would be kept as usual on Saturday.

Furthermore, according to some poskim, mainland Alaska, even west of 144.8°, follows the date of Canada and the U.S. In other words, the dateline does not cut through the land mass of Alaska. (If it were to cut through, then a situation conceivably could arise where two people might be standing next to each other, and one would be observing Shabbos and the other not.) Rather, the dateline follows the coast of Western Alaska, down and around its peninsula, and up towards Valdez. At the 144.8° longitude line, the dateline cuts straight down into the Gulf of Alaska and the Pacific Ocean. A person who crossed this dateline while at sea on Friday would be sailing into Shabbos. If he then disembarks in Western Alaska, he is now relieved of Shabbos obligations, since, according to these opinions, it is Friday on land.

Generally, around-the-world cruises also present dateline concerns. For instance, one such cruise travels westward from the U.S. to China. On this cruise, all the possible halachic datelines are crossed. One would have to carefully track the ship in order to determine what he is permitted to do in each part of the world. What locals call Friday or Sunday in some places may actually be Shabbos.

Dateline determination also affects issues such as Yom Tov, ta'anis, tefilah, tefillin, and sefiras ha'omer.

Also see, A Traveler's Guide to the International Dateline