Where does «estribor» come from?

Question

In Spanish, the right side of a ship (and everything beyond said side) is called «estribor». I know enough about sailing to guess that it can't possibly have anything to do with a «estribo» (which is where you put your feet when you ride a horse). So more than once I've wondered: maybe «estribor» comes from English «starboard»?

I've done my fair bit of research:

• RAE dictionary says «estribor» comes from old French «estribord». However, I've checked the etymology for modern French «tribord» on some French dictionaries and they say it comes from «stirbord» instead; no references to «estribord».
• NGRAM has nothing for «estribor» before ~1740...
• ... but CORDE has registered uses for «estribor» from as early as 1525. Then again, I highly doubt that «estribor» was already written like that in early 16th century.
• Finally, the Lexicon Tetraglotton, an English-Italian-French-Spanish dictionary from 1660, says Spanish for «starboard» in s. XVII was «estroiborda». Probably a mistake, but there's that.

So... I'm aware that most European words for «right side of ship» come from some old Indo-Germanic-Something root meaning «the side of the steering stick». But where does the current writing of «estribor» come from?

Answer 1

Etimologías de Chile sugiere que estribor se formó a través del francés estribord (que ha evolucionado a su vez hasta el actual tribord) y que esa voz francesa viene a su vez del neerlandés stierboord que es una voz que une los términos "stier" (timón) y "boord" (bordo).

Este otro artículo sobre la etimología de "babor" y "estribor" confirma también que debido la posición del timón que permite manejar el barco (a la derecha, por ser más fácil así de ser manejado)

[...] para distinguir la izquierda de la derecha en el mar, se usó el medio más claro, ya que se tomó como punto de referencia el principal elemento de asimetría de un barco tradicional: la posición del timón en el lado derecho.

[...] se le llamó [al lado derecho del barco] ‘lado o borda del timón’, cosa que en neerlandés se dice stierboord.

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Etimologías de Chile hints that the Spanish estribor comes from the French estribord (the archaic form of the current tribord) which in turn comes from the Dutch stierboord a word that combines "stier" (tiller) y "boord" (on board).

This article explains the etymology of the Spanish "babor" y "estribor" based on the position of the boat's tiller. The tiller was the main element to divide the boat in two sides, left and right. The right side of the boat, where the tiller was, was called in Dutch stierboord