单项选择题 You are running parallel to the coast and estimate that the current is against you.In plotting a running fix using bearings from the same object on the coast，the greatest safety margin from inshore dangers will result if what speed is used to determine（）.

单项选择题 You are making tow.A loaded，open-hopper barge with independent tanks has placards，with alternating red and white quadrants，located at each side and end.You inspect the barge and find slight traces of water in the wing voids due to condensation.What（）.

单项选择题 You are entering an east coast port and see a buoy with a yellow triangle painted on it.This indicates（）.