What is the nature of the mitzvah of lighting candles on Chanuka? (Shabbos 21b)

Is it a mitzva of לילה? Or is it a mitzva of פרסומי ניסא? It is clear that the reason for the mitzva is פרסומי ניסא, the question is how did chazal make the takana? Did they make it a regular mitzva of לילה like so many other mitzvos or did they make the takana as well a mitzva of פרסומי ניסא?

This would seem to be a machlokes harishonim. The gemara wants to know why the language of משתשקע החצה עד שתכלה רגל מן השוק, is used. The gemara offers 2 answers, אי לא אדליק מדליק אי נמי לשיעורא. Tosafos there understands this to mean as follows. the first answer is saying that if you did not light in this time (from shkia until תכלה רגל מן השוק) you missed the mitzva and cannot do the mitzva anymore, the second answer argues and says that it is coming to tell us how long the candles must burn. The Rambam as well understands the first answer as Tosafos, the Rambam however holds that the second answer is not arguing, rather it adds another requirement, how long the candles need to burn. The Rambam understands that these 2 go together and that the shiur is not in time but rather from when you light until תכלה רגל מן השוק. This is meduyak in the Rambam because he writes that תכלה רגל מן השוק is כחצי שיעור או יתר. The Rambam clearly states that the shiur of תכלה רגל מן השוק could be longer then a half hour.

According to both Tosafos and the Rambam it would seem that the mitva is a mitzva of פרסומי ניסא and therefore if you light after תכלה רגל מן השוק you are not יוצא. The Rashba however writes that the gemara did not mean that you are not יוצא at all. Rather you are not יוצא the way the Chachamim wanted but you are certainly יוצא the mitzva if you light at night. The Rashba seems to holds that it is a mitzva of night and therefore b'dieved the zman is all night. Lechatchila the chachamim said you should light when there is pirsumei nisa.

The same thing applies to lighting before the zman. According to the Rashba, just like you can do mitzva's of night starting from plag hamincha, you can light from plag hamincha. According to the Rambam there is no such din, lighting is not a mitzva of night and therefore before shkia is simply not the zman.

The obvious question on the Rambam is what about Friday night. The answer is that since Chanukka is 8 days and there must always be a Friday night, Chazal made a special takana on Friday night that you can light before shkia. According to the Rashba we don't need to come on to this, it is just the regular din of doing mitzvos of night from plag.

Shabbas 19a - Going on a boat trip close to shabbas

Here is a short summary of a number of the reasons presented by Rishonim for why “אין מפליגין בספינה פחות מג' ימים קודם לשבת” except if is for a devar mitzva or before three days before shabbas (mostly as summarized by the Ritva)

1. Rashbam (as quoted in Ritva and Tosfos Eruvin 43a) – The issue is one of finishing a melacha before shabbas and only assur according to beis shammai. It seems that there is a dispute if he means the melacha of a goy (the seifa of our mishna) or שביתת כלים. The language of the Rashbam in Tosfos Eruvin is “דלא שרו לעשות מלאכה בע”ש אלא בכדי שיעשו מבעוד יום”. It seems from the Rosh that we are talking about שביתת כלים since he asks the following question: Since the issur is techumim and only derabanan, even בית שמאי are modeh that there is no problem, like טוענים קורות בית הבד ועיגולי הגת. However, according to the Ritva, he quotes עורות לעבדן, and mentions the goy doing melacha for the Jew (again of brining him out of the techum)

2. Rabbeinu Chananel: The issur is techum and only applies to a low boat.

3. Rif: The problem is ביטול עונג שבת as it takes a few days to get used to the water and seasickness. (Can a large cruise be allowed as I assume you barely feel that you are at sea?)

4.Baal Hamaor: going on this trip is that you place yourself in a situation of ספק סכנה and therefore it looks as if you are creating a situation on purpose of being מחלל שבת. So, three days before shabbas is called “before shabbas” and one has to have it in mind. He therefore extends to this to other scenarios as well such as going to a desert (and what Rav Meir mentioned in shiur. Does this relate to cutting your nails three days before shabbas as well?)

5. Tosfos (Ritzba -eruvin 43a): The issur is a גזירה אטו שיטה על פני המים  that you may make a boat or steer such a boat yourself for 4 amos in a karmelis (the water). Since this is just a חשש and גזירה, the takana does not take effect in case of devar mitzva or leaving before three days before.

6. Ramban: the case that is assur is where 50% or more of the passengers on the boat are ישראל and since driving the boat involves a number of issurei torah like tying and untying, if the goy is doing that melacha for you on shabbas, then it is assur. However, this is only when the boat is starting close to shabbas, since if earlier then it does not look like the goy is doing melacha for the  ישראל anymore

It would seem according to all these reasons (except Tosfos and maybe Rif) that you can book your cruise without a problem and thought of when it is leaving. (there is a discussion if and how to go on shabbas as well)

Shabbas 18a - Making noise on shabbas

The simple reading of the gemara is that Rabba’s peshat is accepted and in explaining that the beraysa that says it is assur to to put wheat in a Rechayim is according to Beis Hillel. This then means that the issur is because of hashmaas kol and such is the pesak of Rabbeinu Chananel. However, Rabbeinu Tam has a different reading of the gemara. He understands that Rav Oshaya accepted the reading of Rav Yosef in the beraysa, i.e.  the words מאן תנא שביתת כלים דאוריתא are not discussing the opinion in general, but the beraysa we had just discussed. Thus Rav Oshaya agrees with the peshat of Rav Yosef (and he is the decider of pesak!), in which case the issur of hashmaas kol is not mentioned there, rather the issur by rechayim is due to שביתת כלים. This would mean that we do not have such an issur of השמעת קול learned out from the beraysa and perhaps no such issur exists.

As it turns out, the issue of what the pesak is in our sugya is a major machlokes rishonim, with the Baal Hamaor agreeing with Rabbeinu Tam and Ramban disagreeing. The Rambam omits this din and the Rif seems to be meikil about hashmaas kol as well, though he quotes the opinoin to be machmir due to hashmaas kol. For this reason, the Beis Yosef writes that we can be meikil in hashmaas kol and codifies this in the Shulchan Aruch as well (רנב:ה). The Rema starts by agreeing with this and then writes ויש אוסרים.

For this reason under various circumstances heterim are given even for things that make noise, especially in cases of financial loss. One significant one (and important if you want to do chazara early shabbas morning) is for an alarm clock, as the Rema writes “אע”פ שמשמיע קול להודיע השעות בשבת כי הכל יודעים שדרכו להעמידן מאתמול ”

Rav Meir explained in shiur that the issue of hashmaas kol is based on אוושא מילתא, which means a zilzul in shabbas. What creates the zilzul – if it is the noise itself, then why should the clock be allowed just because people know you set it up before? I think the tzitz eliezer in chelek 4 siman 31 (http://hebrewbooks.org/pdfpager.aspx?req=14503&pgnum=169)  explains this idea. He says that the אוושא מילתא is still connected to whether people will think this is something you may have decided to do on shabbas in violation or obviously did beforehand. In his case, (he is dealing with watering seeds on shabbas where the sprinkler was turned on before shabbas), he feels that that people will realize that you needed to set it up beforehand (due to the urgency of that case), so maybe the idea is the same with the alarm clock – that it is obvious to people that you set up the alarm clock before and therefore the noise itself is less of a zilzul.