The heights of the ships = they have different heights The height of the ships = they all have the same height "The ships' heights" is also correct. We also don't know. We, too, don't know. We don't know, either. All are good. Transport all kindS of cargo, from one marked zone to the other." This is correct!

The first one would indicate several ships for example, "the height of the ships was equal to the tallest building in the port". The sedond one would usually indicate one ship for example, "the ship's height was equal to the tallest building in the port" It doesn't sound natural for example, "You guys don't know the answer? Well we also don't know". A more natural way of saying that would be, "we don't know either". When you use "to the other" in that sentence it means to the other one that is known. That is you are aware of the exact marked that is being referred to. When you use "to another one" it means that you are not specifically stating the marked zone to which the cargo is going to be transported. It could be one of many.

Because you have many ships, "heights" need to be plural. You can say "the heights of the ships" or "the ships' heights". They are both fine. "We also don't know" is good. Or "We don't know either". The last one is not a complete sentence, there is no subject. Or it could be considered a command, however if that is the case, it's a little awkward. Regular sentence: We transport all kinds of cargo over the strait, from one marked zone to the other. Command: Transport all the cargo over the strait, from one marked zone to the other.

"we haven't go a clue either" - has a bit of a ring to it!!!