This weekend we took the train to El Jadida. It was a Portuguese coastal fortress built in 1514, expanded in 1541, and held until 1769.
Portuguese city overlooking the Atlantic.
Last summer I was in South Africa and saw the Castle of Good Hope, built by the Dutch starting in 1666.
African castles visited in 2017.
Portuguese cistern in El Jadida.
Antique cannon at Terrasse des Paresseux in Tangiers
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The castle in Cape Town, with clouds covering Table Mountain
For a number of years I have been using a data set with digitized ship logs from the age of sail. For some information on the source of this data set, try here. The data mostly postdates the building of these fortresses on opposite ends of the African continent, but the weather hadn't changed much, and sailing ships still saw the came limitations. The data set has no digitized logs from Portugal, and I have shown just the Dutch ships before 1755.
Note the large number of ships sailing south along the coast, past the Portuguese fortress; the winds are favorable for this. Approaching the equator, the ships wanting to travel fast to the Indies go straight south and do not try to hug the coast. Those that do hug the coast, sail very slowly (blue vectors), and give up before they cross the equator. They could in fact be engaged in the slave trade; this data set has an almost infinite number of questions it could be used to address. The ships going to the Indies would pass Cape Town, and the Dutch colony there could resupply then. The ships on the return voyage would initially sail north along the coast, and then swing far west to catch favorable winds back to Europe.
Routes of Dutch ships before 1755. Colors show ship speed (blue is slow; purple relatively fast considering these were big lumbering merchant ships) and the arrows show the direction of travel.
Annual wind patterns, which go a long way to explaining the overall sailing patterns. Both the vector length and color correspond with wind speed; 10 m/s is 22 miles per hour
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