Port makes sense, never thought about it. Ships I see rarely, so I couldn't tell which side they use (or even both depending on the harbor) But for passenger planes it's definitely left.

In German starboard is steuerbord, steuern = to steer. No shifting over the centuries.

However, port is still backbord. I am not familiar with Northern dialects (where they have a coast), back does not tell me anything. Maybe packen = to pack/load)??? Interestingly enough the English argument that the 2 words should not be too similar has not been applied. Maybe because there are already 3 vs. 2 syllables? Whereas English had 2 and 2 so they changed to 2 vs. 1 to make it make obvious what was said even in a big storm?