Sail beyond the start line, sight along it and find an object on shore that is on the line.
航⾏到起航线外侧,沿着起航线观察,选择岸上⼀处与起航线对⻬的参照物。
You can now tell if you are up to the start line (or not) by sighting the end of the line with the object beyond it. Be aware that quite a lot of the boat protrudes in front of you. A reads the transits and starts on time.