Pentland Firth

Geographical location

Pentland Firth ( freely translated: " the strait in the country of the Picts " ) refers to the strait / the sound between the Scottish mainland and Orkney. It was created (before are dating, but are controversial ) by rising sea levels in the post-glacial period, sometime 12000-10000 BCE.

Importance

The Pentland Firth is considered because of its extreme flow and wind conditions as one of the toughest seas in the border area between the North Sea and North Atlantic. Thus, for example, in the Indienststellungsfahrt of MV St. Sunniva, a ferry to the shipping company P & O - Peninsular and Oriental Line - in the 1980s, a Kaventsmann smashed the bridge deck so that the ferry in the protection of the Scottish coast, running back to Aberdeen had.

Almost 100% of the failing crossings at the Ferry Lifeline service between Orkney ( Stromness ) and the Scottish mainland ( Scrabster ) are not generally on the account of adverse weather conditions in the waters around Orkney or off the Scottish north coast, but solely on the account of the conditions for the decisive 4 nautical miles between the south coast of Hoy and the mainland at Scrabster.

Tidal rapids ( Tidal Races )

The Firth is well known for the intensity of the tidal stream associated because of its high flow rate among the most powerful in the world. But the only 7 km wide main stream between Duncansby Head and Muckle Skerry leads on average about eight times as much water as the Amazon. Therefore, this area is also referred to as the " Saudi Arabia of tidal power ". West of the Pentland Skerries ( about 30 km / h) were measured up to 16 knots. Elsewhere significantly higher peak speeds are achieved, but because of the small cross-sections and the lower average speed have little total volume flow ( Saltstraumen 22 knots or Skookumchuck Narrows in British Columbia with 17 kn). The power of tidal currents leads to Stromkabbelungen and tidal rapids that can occur at certain times of the Tide currents. Some of the main rapids are:

• ' The Merry Men of Mey '. Southwest of stroma; of St John 's point across the Firth towards the goal Ness on the island of Hoy. Especially on a 25 m shallow sandbar 5km west of stroma formed during westgerichtetem current ( Weststrom! ) and wind from the west ( Westwind! ) constant standing and permanently breaking waves several meters high. The speed of the tidal current can be 10 knots ( 18.5 km / h ) top.

• The ' Duncansby Race' always flows in an easterly direction! It starts after low water with the incoming tide flow along the northeast side of a 10 m deep and 2 km long shoal Boar of Duncansby first immediately before Ness of Duncansby to southeast. With increasing flood flow and increasing water depth above the Boar of Duncansby flows over the next two and a half hours more and more water faster and faster over the shoal, now after east-northeast. Here is another race created the west parallel to the coast before Ness of Huna. After flooding, the go northwest tide creates a Nehrstrom counterclockwise, so that in turn is a walking to northeast flow over the shoal. Even before Duncansby Head east to form different phases of the tide rapids with varying but always dangerous character. It is particularly dangerous in stormy winds against the Tide currents, since the vortex interrupt the transport of energy within the storm waves, so that their kinetic energy is converted into potential, the wave builds up a wall of water and breaks down the next moment under gravity.

• The ' Liddel Eddy ' ( Liddelnehrstrom ) forms at high tide between the islands of South Ronaldsay and Muckle Skerry.