Question: Why regarding a Mavuy it calls it a Lechi, and regarding a Chatzer it calls it a plank, in the entire Sugya? Both of them are Mashehu [wide and thick, and 10 Tefachim tall]!

Implied question: Why didn't [Rav Nachman] say that the Halachah follows Rebbi regarding Pasei Chatzer? Rebbi holds like R. Eliezer, like we say "and Chachamim agree", i.e. Rebbi agrees to R. Eliezer!

It would be better [to rule like Rebbi], for he discusses a Chatzer!

Answer: [Rav Nachman] prefers to mention R. Eliezer, who was mentioned in the Mishnah.

Opinion #1: We must say that Rebbi and Rabanan argue about a square Chatzer. According to Rabanan, a plank Mashehu suffices, and Rebbi requires two planks, and each is Mashehu.

Proof: If they argue about when the length is greater than the width, Rav Nachman contradicts himself, for here he rules like Rebbi, and at the end of the Sugya Rav Nachman said that the Halachah is, if the length of a Chatzer is greater than the width, a Lechi Mashehu permits it!

Rather, surely they argue about a square Chatzer, and it needs two planks, each two Mashehu's, or one plank of four [Tefachim], like Rav Nachman says at the end of the Sugya that a square Chatzer is permitted through a plank of four [Tefachim].

Opinion #2: Rashi explained below (DH Rebbi), that [R. Yochanan says that if the plank is] on one side it must be four [Tefachim], and if it is on two sides, each is Mashehu, according to Rabanan.

Rebuttal: According to Rabanan, a one plank Mashehu suffices, like we explained! Rather, [R. Yochanan] holds like Rebbi, for this is the Halachah.

Explanation: Now, had it said four [Tefachim], this would not teach a Chidush more than the majority of a wall;

Just the contrary, now that it taught the majority of a wall, this is a bigger Chidush! Even though it is not four [Tefachim], it suffices, since there is the majority of a wall. Why do I need four [Tefachim]?

Explanation: Why did [Shmuel] err to obligate four [Tefachim]? Three and Mashehu suffice, for now even the majority of a wall is not needed, since the gap was diminished to less than four [Tefachim]!

Alternative text: Some texts say "why do I need the majority of a wall?" According to this, the Gemara is fine simply.

Alternative text: Some texts do not say "the majority of a wall", only "why is this needed? Three and Mashehu suffice!" This [means] just like [the previous text].

Explanation #1 (Rashi): [There are Gidudei, i.e. remnants], but the sea covered them.

Question: In any case, why is Tiltul (carrying) different? Regarding Tiltul they are considered Mechitzos, but regarding drawing water they are not considered Mechitzos!

Answer: It means that one may not draw, i.e. it is forbidden to carry from the house to the Chatzer [or vice-versa]. It mentioned drawing because the primary use from the Chatzer to the house is drawing;

However, Tiltul in the Chatzer is permitted. What is the reason? We answer that there are Gidudei, and the Mechitzah is recognizable to the people of the Chatzer;

It is not recognizable to the people of the house, who are far away, and water mixes. Therefore, it is forbidden.

Question: Below (86a), it connotes that it is fine that we do not require seeing the tops of the sticks [of the Mechitzah], if not that Rav Yehudah is adamant about water mixing. [According to Rashi], also this Beraisa [requires recognizable Mechitzos]!

Answer: The Gemara could have said ul'Taimech. (There, Rabah bar bar Chanah challenged Rav Yehudah. We could have challenged him from our Beraisa, which requires recognizable Mechitzos.)

Explanation #2 (Rivan): We discuss a Chatzer that was breached before Shabbos, and water came on Shabbos. It says here "what is the case? There are Gidudei." Therefore, one may carry, for once Shabbos was permitted, it is permitted, even though now the walls are not recognizable;

However, to draw from the water that came on Shabbos, "once it was permitted, it is permitted" does not apply.

Explanation #3 (Rashbam, R. Tam): It has Gidudei, i.e. there are Gidudei 10 [Tefachim] tall to the sea, in the Chatzer. Therefore one may carry in the Chatzer;

However, to draw from the water is forbidden, for the place of the water is totally breached to the sea, and the sea is Karmelis.

Implied question: We should be concerned lest the sea deposit debris (and the Gidudei will not be 10 Tefachim taller than the debris, and they will cease to be Mechitzos)!

Answer #1: The Gidudim are much taller [than debris that would be deposited].

Answer #2: [The Gidudim] are far from the shore [debris will not be deposited there].

Explanation #3 (ha'Sar mi'Kutzi): [The Gemara said that] one may not draw water, and also Tiltul is forbidden. It mentioned drawing water, because the Beraisa said "one may not draw";

[The Gemara inferred] but one may carry, if the water went away. What is the reason?... There are Gidudei;

Therefore, it is permitted when there is no water, but when there is water, and the Mechitzah is not recognizable, and water mixes, it is forbidden.

Question: Why is it forbidden to draw water here? A Tosefta (6:27) teaches that if a balcony is above water, one may draw from it on Shabbos only if he made a Mechitzah 10 [Tefachim] tall below the water, and [then it is permitted] even if the water floats [on top of the Mechitzah];

Inference: Even though the Mechitzah is not recognizable, one may draw from it!

Answer #1: There, the Mechitzos are made for the sake of the water. They are better than Gidudei of here.

Support (for Explanation #1 - Ritzva): There are Gidudei, but the sea covers them. Therefore, one may not draw, lest he draw to the other side outside the Chatzer;

The reason that water mixes forbids only lest he draw to the other side, and not because the Mechitzos are not recognizable.

[One may draw if the breach is at most] 10, which is like an opening. We are not concerned, for there is a Heker. However, [in any case] we may carry, even though the Mechitzos are not recognizable.

Answer #2: Now, the Tosefta is fine. (There, a Mechitzah permits drawing even if it is not recognizable, for there is no concern of taking water to the other side.)

Explanation: Even Rabanan say only that mid'Rabanan we require three full Mechitzos. (They can agree that mid'Oraisa, a Lechi or Korah is a Mechitzah. Therefore, Rabah and Rava cannot say that they hold like Rabanan.)

Alternative text: Some texts do not say "Arba'ah", for now R. Zeira is thinking that a plank Mashehu suffices.

Disclaimer: There is no need to change the text due to this. It says Arba'ah due to the conclusion.

Implied question: Above, R. Zeira himself said that from one side, four [Tefachim] are needed!

Answer: He heard that after [asking] this [question].

Explanation: Two Chatzeros are open to the Mavoy, and two houses open to each Chatzer.

Support: It says so in Shabbos (131a).

Question: A Chatzer that is not square, how is it permitted through a Lechi or Korah?

Implied suggestion: A Chatzer has residents, therefore it does not need houses and Chatzeros. However, a Mavoy is far from residents, for the Chatzer separates between the houses and the Mavuy. Therefore we require many residents - two Chatzeros, and two houses for each Chatzer!

Rejection: Below (73b), Rav said that a Mavuy is permitted through a Lechi or Korah [only if houses and Chatzeros are open to it], and Shmuel said even one house and one Chatzer;

Rashi explained there that one house is in the Mavuy without a Chatzer, and one Chatzer with houses;

[According to the suggestion,] since Rav's reason is due to residents, also Rav agrees. Since there is a house in the Mavuy, even if there is no Chatzer, it is permitted through a Lechi or Korah! We must explain like Rashi explained.

Implied suggestion: Perhaps [Shmuel said even] one house and one Chatzer, i.e. one house in one Chatzer!

Rejection: R. Yochanan said there even a Churvah (ruin), and it says afterwards that we are not concerned lest he come to take Kelim of the houses to the Churvah;

Inference: He does not mean a Churvah in the Chatzer, for if so, there are no houses! Rather, [R. Yochanan] means a Churvah without a Chatzer, and similarly Shmuel, who said even one house and one Chatzer (discusses a house without a Chatzer).

Answer: Because a Mavoy is closer to Reshus ha'Rabim than a Chatzer, it requires houses and Chatzeros.