S1:Mr. Pilot, I am captain. This is my first voyage through the Suez Canal. Could you tell me something about the convoy pattern?S2:Well, usually, there are three convoys a day, one northbound convoy and two southbound, because of the insufficient depths in the northern part of the Canal.S1:How long does it take to transit the whole Canal?S2:For the Northbound convoy, it take about 12 hours while, for the southbound, 16 hours or so. That's mainly attributed to deeper depths in the southern part of the Canal. The northbound convoy has almost a free run from Port of Suez to Port Said.S1:Oh, well, I see. It's side that each ship has to change several pilots during transit. Is that true?S2:Yes. Four pilots are assigned for each ship throughout its trip in the Canal.S1:What about the transit speed and safety margin between two ships?S2:The speed limit is 8 knots for tankers & deep draft ships and 10 knots for other ships. The distance between vessels should be kept not less than 1 mile in a convoy.S1:How many ships transit the Canal in a day, sir? S2:Usually, fifty or so. In 2008 , about 22,000 ships transited the Canal. Well, the pilot boat is coming. I'll hand over the watch to the next pilot. Please stand by the starboard gangway and pilot ladder.S1:All right. Thank you for your information. Q4:How many ships transit the Canal in a day?