Here are a couple of interesting notations from the Tirpitz war diary describing the run along the Norwegian shoal route to the North for Operation Rösselsprung. At Rörvik the narrows are only 350 wide; I don’t know the width of the shipping channel and its depth. At Sortland the narrows are 1000 ft. The tides are 20 ft and, for example, at Bodö there is the world record spot for a current of 7 kn! But the Tirpitz took the risk and sailed through shallow and narrow waters, with following, probably strong, currents. I think this is a remarkable accomplishment of seamanship, but would you take such a great risk with a ship of that value and size. They had a Norwegian pilot aboard who knew the area, but he did not know what the ship could do.
3 July 1942
01.40/0140 [Juli Mitternachtsonne!/July midnight sun!]
Vor Rörvik.
Off Rörvik.Schlepper “Atlantik” meldet sich zur Hilfeleistung, wird nicht benötigt. Enge [350 m breit] wird trotz Mitstrom ohne wesentliche Schwierigkeiten (geringe Maschinenhilfen) durchsteuert. 9 – 12 sm Fahrt.
Tug “Atlantik” reports ready to assist, but is not required. The narrows [350 m wide] are transited without considerable difficulties despite the following current (minimal engine assistance). Speed 9 – 12 knots.
and
21.02/2102
Sortland-Sund.
Beim Passieren des Sundes keine Schwierigkeiten [Enge bei der Brücke 1000 m] . Geringste Lotung 13 m [Tieftgang der Tirpitz ist 10.6 m!]
Sortland Sound
Transited the sound without difficulties [narrows at bridge 1000 m]. Least sounding 13 m [draft of Tirpitz is 10.6 m!]