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C - 6 : Why Sailors love Ports and hate the Bora

Remember the trees in the Rhone Valley in Southern France which are bent due to the strong Mistral? The area around Chantrou, our house near the Provence, is full of them. A Mistral usually occurs when a strong high pressure system over the British Islands and a depression over the westerm Mediterranean persists. The two pressure systems equalise. A a fast, dry wind flows North - South and can easily reach 150 km/h. Often the Mistral blows for days

Typical Mistral tree in the Provence

The Mistral is not the only long-distance weather system in the. Mediterranean. In 2017 we were running into the Meltemi when crossing from the Peloponnes to Bodrum in Turkey. We experienced wind speeds of over 100 km/h and waves two meters high for two days. Luckily our Carpe Diem was a big, sturdy boat!

Behind Amorgos (Greece) on 12 August 2017

The Dalmation coast knows similar winds that can be equally violent. Frequent in winter and rarer in summer, it forces sailboats back to the harbours. There is now a sophisticated early warning system that alerts crews of any incoming Bora, as the wind is called. There is a small chance that we will encounter one during our journey to Venice. But a Bora does not last long and blows out within a few hours. We would simply seek shelter in a nearby harbour or a well protected bay.

Bora in September 2018 - weather map

The Bora is one of the reasons why the Venetian sailing season was limited from June to September each year - just enough time to make it back from the trading towns in the Levante or Alexandria. The Venetian Galleys were simply to fragile to ride out a Bora in open waters. Without sophisticated warning systems, the Venetian mariners had to rely on other clues to detect incoming Boras. Usually, the air temperature increases unexpectedly before a Bora starts blowing. If the Venetians could not make it to the next harbour, they rowed to the next beach and pulled their Galleys on the shore.

Dynamics of a Bora occurence which accelerates when flowing towards the Mediterranean

A Bora would not only create stormy gusts which easily rip apart a sail - were they not as sturdy as today’s - and whip up high waves, it also creates a 5 - 20 m thick layer of mist which essentially blinds a sailing crew. It is like sailing in a fog with visibility limited to 5 - 10 meters. Not a good situation to be in on such rocky coast as the Dalmatian!

Choppy waters and the typical Bora mist

The high density of Venetian harbours along the Dalmatian coast thus has one more reasons. Avoid sailing blind in the fog! Fragility of Galleys, the need to rest the crew after eight hours of rowing (30 miles), the lack of precise nautical instruments and the persistent fear of pirates were the others.

Human ingenuity would not be what it is if someone did not find a way to use the Bora’s drying properties.: Pršut, the Croatian ham is made by drying ham over winter in the open in the Bora. Croatians swear that their Pršut is better than the Italian Prosciuto di Parma or the Spanish Serano ham - let’s see. We have time to assess the Croatian claim!

Pršut from Croatia

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