If you can think of another couple of examples, you'll persuade me to change the word 'marginal' to 'minimal' ;-)
Back in the day the rudder had not yet been invented, so they used a slightly oversized oar to steer (dutch: stuur) the ship. It was not practical to fasten it exactly in the middle, so it would have to be either on the right or the left side of the ship. Because most helmsmen were right-handed, the oar usually got fastened to the right side, which was henceforth known as the stuur-boord, literally the board of the ship that the steering oar was fastened to. Because the uu-vowel doesn't do too well in English, it got turned into starboard, which is still used today. Coincidentally, because the steering oar was in the way when mooring the ship it became customary to moor the ship on the 'left' side. This then became known as the 'port' side because the port was always on that side.
Jag styr min båt. Jag styr på styrbord. I steer my boat. I steer on starboard.
The Swedish styr is pretty much like the English steer but rounded instead of flat, if that makes sense, and means the same. And bord can be a board.
So, steering board.