Large Vessels

This is an incomplete idea, but as a certain R.Y. likes to say, “it’s a starting point.” Thanks to a friend of mine for giving me some of the m.m.’s on this topic.  The Mishna in Kelim (15:1) says הַשִּׁדָּה, וְהַתֵּבָה, וְהַמִּגְדָּל, כַּוֶּרֶת הַקַּשׁ, וְכַוֶּרֶת הַקָּנִים, וּבוֹר סְפִינָה אֲלֶכְּסַנְדְּרִית, שֶׁיֶּשׁ לָהֶם שׁוּלַיִם, וְהֵן מַחֲזִיקִין אַרְבָּעִים סְאָה בְלַח, שֶׁהֵם כּוֹרַיִם בְּיָבֵשׁ, הֲרֵי אֵלּוּ טְהוֹרִין.  The reason, explained in the Gemorah in many places, including Bechorot (38a,) cited in Bartenura here is דומיא דשק בעינן מה שק מיטלטל מלא וריקן אף כל מיטלטל מלא וריקן.  There is a hekesh from wooden vessels being susceptible to tumah to sack (Shemini 11:32,) so it has to be similar in that it can be moved even if its full as opposed to these large vessels that cannot.  Rashi in Eruvin (14b) and Menachot (31a) explains the din שמחזיקים מ' סאה בלח שהן כוריים ביבש יצאו מתורת כלי ואין מקבלין טומאה.  It’s not just a גזירת הכתוב that since its not similar to sack, these vessels don’t receive tumah, but the logic is that they lose their name of being a כלי. 

This understanding may be supported from the fact that we find regarding other dinim such large vessels aren’t considered כלים.  The Tosefta Yadayim (1:6) states that one may not use such a vessel for נטילת ידים and the Chasdei Dovid gives the explanation since its not considered a כלי.  The Gemorah in Shabbos (35a) brings this Mishna to prove that large vessels can’t be moved on the Shabbos because they are no longer in the category of כלים.  Similarly, in Ohalos (9:12) we find that this type of a vessel acts as a אהל to block tumah.  This idea of viewing these vessels as a אהל and not as a vessel is also reflected in Eruvin (35a. [see Rashi and Ritva there].) 

This idea is used by the Pnei Yehoshua Shabbos ((83b-84a) and the Mishna Achrona Kelim (24:1) use this idea to explain the opinion of the Rambam that there isn’t even any טומאת מדרס on these vessels.  Tosfos Shabbos (84a) holds there is for it can still be used to sit upon.  They point out that it sounds like the Rambam disagrees and explain because it’s not considered a vessel and is hence not subject to טומאת מדרס. 

However, we do find two places that seem to contradict this assertion.  The Mishna in Parah (5: 5) says one may use a boat to sanctify the waters of the פרה אדומה even though they require a vessel to sanctify them (see Tos. Yom Tov for possible different interpretation of the Mishna.)  We see from this Mishna even large vessels constitute as vessels.  This runs contrary to the understanding that they aren’t considered vessels? [One may easily escape this difficulty because there is an opinion in Tractate Shabbos (ibid) that a boat isn’t susceptible to tumah because of a special possuk and the Tannah may be following that opinion.]  However, what must be understood that regarding other vessels besides wood, where there is no hekesh, even large vessels are tamah as we see the Gemorah in Shabbos says regarding earthenware vessels.  According to the above approach they should be tahor for they aren’t vessels? 

Its also noteworthy that Tosfos in Pesachim (109b) brings that the Yerushalmi asks how could the yam Shlomo made be valid as a mikvah it should make the water מים שאובין and invalidate the waters?  Tosfos proves from here that even large vessels are considered a כלי and will make the water שאובין.  [Tosfos may hold that large vessels are considered כלים, see Tosfos in Menachos, Shabbos 35a.]  However, will Rashi agree to this din?  [See שיעורי ר' יחיאל מיכל in all the places and משנה טהרות.]