Tradition holds that answer to be the correct one. The reason is because
the steering-board or oar was usually located on the starboard side
which prevented the ship from docking on to starboard.
Selected sentences from my handy dandy book of nautical terms:
"Starboard is a corruption of the Alglo-Saxon steorbord (steer board)
which hung over the right-hand side of the vessel.
The left hand side was known as larboard (loading side).
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And here I thought was because they kept their wine on the Left side to
keep the sun and stars from shining on it and thus affecting the
bouquet.......

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