Ah, that Map... I stopped short of having each line input separately to match the colours, but still didn't get them right.
Took me a while this week - engrossed in Tableau Conference-ish! Always love a nautical challenge. Not sure I took the most efficient route, and had one key difference - buoy colors in the challenge output are reversed, so I corrected. While in the US, returning to harbor the red buoy's are on the right (Red-Right-Returning)... the UK is opposite. https://www.belfast-harbour.co.uk/documents/download/254 for your perusing fun!