Is 出国时船过香港 coherent?
船过香港 in this context is short for (他乘的)船经过香港. It is not a common way to speak, (more literary than colloquial) but native speakers would have no problem understanding what it means
If you say 路过香港, we would not know you're on a boat and would presume you personally visited Hong Kong briefly
Similarly, we can understand 枪指众人 = 用枪指吓(向)众人; 车弃路旁 = 把汽车弃置在路旁