Bottom Sludge

Seafarers could also be fooled by normal aids. During high seas and where there was shallow water bottom sludge could be churned up to the surface.

In the shallowest areas of the North Sea this was quite common. Bottom sludge is usually pointer to the nearest land but not in these cases and you could be fooled by nature.

Finding the Depth

Finding the depth with a sounding lead or bar was only used in waters with a relatively flat bottom. During river navigation it is reasonable to assume they used a sounding bar.

Speed - Distance

The most difficult thing was to calculate the distance you had travelled. It wasn't possible until the chronometer was invented in the 1700's. There was no measure for the distances they had sailed. Length was therefore measured in sailing days. It was a certain number of days to the Faeroes and a certain number to Iceland.

Where's the Town?

Finding the entrances to the markets wasn't always easy. They weren't always at the mouth of rivers but on the riverbank a bit inland. many of the approaches were therefore marked by some sort of aid. Ex. Adam of Bremen mentioned a sort of lighthouse at the mouth of the Oder.

- 14. august 2004 -