Navigation in Southern North Sea

Navigation in Northwestern Europe is fantastic. There are various components to be considered before departing, and also on the way. This turns route planning into a strategic game with many tricky components.

Next to geography and wind direction and force, the perhaps most important item is the tidal streams. Tidal streams are motion of the entire sea, depending on actual position of earth and moon. The vast mass of moon works as a field of gravity for things on earth. If that thing is a large area of liquid (e.g. the sea), the weak gravity of moon is still strong enough to makes the liquid on earth moving. Wherever the water is drawn into a corner of land mass where it can no longer move to the side, then the sea water level will rise.

Why is this of importance to us as sailors. Lets say that a boat is traveling with a speed of 6 knots (this is what we want to see as an average). The current of the water we are travelling in has a speed of 1.5 knots. The boat against the current makes good only 4.5 miles per hour, whereas the boat going with the current makes 7.5 miles. A distance of 22.5 miles is therefore made in either 3 hours or 5 hours. Our average daily traveling distance in this first phase of out trip is however 32 nautical miles (60km).

The tide certainly doesn’t start to flow into your direction at the time you are
ready to leave. We use tidal stream maps and tables and plan departure times usually for the two traveling legs in ahead. Markus likes this game very much and will miss it, once we leave North Sea (tonight) and the English Channel (in about 2 weeks time.

By the way, doing a regatta in tidal waters requires a lot of knowledge, especially when there are submerged sand banks with changing water depth. The stream will usually be quicker in the channels, and an almost won regatta can be lost if your final course leads through shallow waters.

My regatta skipper George always said that regatta sailors are often the better cruisers. And yes, four Dutch sailing yachts confirmed that it could be like that. Three days ago, those guys were racing down the coast, ourselves being far more away from the land. For many hours it seemed that they would arrive in Scheveningen before us. The slightly bent coast line however made them going straight against wind and wave for the last two hours, and this was why we got the last nice berth in the harbor, not one of them. I was jumping with joy!

What other complications can be found out there? The better issues are objects which do not move, such as huge wind farms, containing dozens of wind mills, or off shore drilling platforms for oil or natural gas. There are fish and mussel farms, same as hundreds of ship wrecks sea bed cables and munition deposing grounds from the past. Better don’t drop your anchor there.

Movable things can include commercial vessels, and if you check on ship tracking sites such as http://www.marinetraffic.com you can easily spot that the Southern North Sea belongs to the sea areas with one of the densest cargo ship traffic in the world, same as Strait of Malacca in Singapore area.

Our issue with this is that from time to time, we have to cross this well organized shipping lanes. The big guys are usually 3 to 5 times as fast as we are. With some optical aids and transponder information from everyone, we can estimate quite well where we can still go and where we should better wait until the big guys have passed. In a shipping lane which is marked like that on the map, these guys have priority. In a more coincidental vessel crossing far out on the sea, it is the sailing vessel who has right of way, at least in theory.

When we come to the conclusion that there is still room enough to pass on front of a commercial vessel, then we want to be sure to have a plan B in case our propulsion fails in front of the other’s bow. He cannot stop, perhaps just change course by two or three degrees. For this reason we always call the big guys on the VHF radio before passing ahead of them.

Other things which are there on and off can be fishing vessels or army firing exercise. Whereas army exercise is broadcasted on the VHF, the fishing vessels move totally unpredictable, as the fish goes. These can be the toughest ones especially if sailing at night in coastal areas. It is sometimes difficult to understand where the fishermen are going, particularly when many lights from land interfere with the fishing vessels lights.

That can be what’s going out there. Usually we love it, sometimes we hate it, for example if one cannot go to the toilet just because fish have no plan where to go next 😉

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