The world seas are heavily sailed these days. Mega container ships sail from port to port, delivering their cargo along the way. Modern inventions such as satellite navigation, internet and ECDIS steer these vessels across our oceans. But once upon a time, these methods were not available and sailing across the vast world seas required a different set of skills. The knowledge of clouds and waves and a steady hand when using the sextant to determine one’s position on the globe. Meticulously recording the ships position on the charts and keeping track of the speed while on the voyage. Although our Dutch Tall Ships are required to have the modern methods for navigation, we still use our old-school sailing skills as well. If you are interested, our crew will teach you all the ins and outs about celestial navigation, how to use a sextant, what the clouds can tell you about what weather is coming and all the other secrets of sailing a tall ship across the oceans!
Celestial navigation is based on the use of a sextant which measures the vertical angle between an astronomical object and the horizon, called taking a sight or shooting an object. You have to note down the time you made the observation. Together the angle and the time can be used to calculate a latitudinal (north - south) position on a nautical map. When the sextant is used to measure the angle between the moon and another astronomical object one can determine Greenwich Mean Time, and hence longitude (south - west).
“Red sky at night, sailors delight. Red sky in morning, sailor’s warning.” This proverb is perhaps the best known, and it certainly holds some truth. If a red sky appears in the east, at sunrise, it means the light of the rising sun lights the undersides of moisture-bearing clouds. The proverb assumes more such clouds coming in from the west. Red skies at night trusts on the fact that there must be a clear path from the west, so there for the prevailing westerly winds must bring clear skies.
“Mackerel skies and mares’ tails, make tall ships carry low sails.” The mackerel in this proverb refers to altocumulus clouds and the mare’s tails to cirrus clouds. Seeing these in the sky can be an announcement of a low-pressure system. In the immediate future the weather will be good, but a warmer front is approaching, which together are the ingredients for a storm. As the low-pressure system rolls in, the clouds will thicken until it starts raining. Ships will in preparation of this weather forecast lower sails and close hatches in preparation for the incoming bad weather.