ST. CROIX NATIONAL SCENIC RIVERWAY
This National Scenic Riverway consists of 252 miles of the St. Croix and Namekagon Rivers, including a section of the former which serves as the MinnesotaWisconsin border.
Minnesota Guide for Tourist Photo Gallery
Later in the war, 37-mm twin mounts were tested experimentally on a few boats, but the snort had by then already reduced the threat from aircraft. Apart from these standard AA modifications on Atlantic boats, further experimental modifications were carried out on other boats but never became a standard form. Modifications were made to all frontline or working-up boats regardless of their date of commission and, during yard layovers, boats were continually upgraded to the latest version. The operational diving depth of a VIIC boat was 100 m (328 ft), with a maximum depth of 165 m (541.33 ft) and a crush depth of 200 m (656 ft). A crash dive to 20 m took an average of 30 seconds. The VIIC/41 boat was the same in almost all respects as the VIIC but was designed with a stronger pressure hull, which gave the boat an operational diving depth of 120 m (394 ft) and a crush depth of 250 m (820 ft). Both the VIIC and VIIC/41 boats carried between 44 and 52 crewmen. With increased AA armament in 1943-1944, crew numbers were at their highest. Following the introduction of the Schnorchel the crews were often reduced to 46-50 men.