Reference for Shabbat 201:2
אמר רב הונא הני ביצאתא דמישן אין מטלטלין בהן אלא בארבעה ולא אמרן אלא שאין בפחות משלשה ארבעה אבל יש בפחות מג' ארבעה לית לן בה ואי מלינהו קני ואורבני לית לן בה
R. Huna said: As for the canal boats of Mesene,<span class="x" onmousemove="('comment',' V. p, 174. n. 8. ');"><sup>3</sup></span> we may carry in them only within [a distance of] four cubits.<span class="x" onmousemove="('comment',' So MS.M. These boats are very narrow and taper to a knife edge in the water. Being thus less than four handbreadths wide at the bottom they do not count as private ground (v. supra 6a), and therefore one may not carry in them. ');"><sup>4</sup></span> But we say this only if they lack [a breadth of] four [handbreadths] at less than three [from the bottom edge]; but if they have [a breadth of] four at less than three, we have no objection; or if they are filled with canes and bullrushes,<span class="x" onmousemove="('comment',' Up to the height where they have a breadth of four. ');"><sup>5</sup></span>