The Type XVII U-boats were small coastal submarines which used Hellmuth Walter

Hellmuth Walter

Hellmuth Walter was a German engineer who pioneered research into rocket engines and gas turbines...

's high test peroxide

High test peroxide

High-test peroxide or HTP is a high -concentration solution of hydrogen peroxide, with the remainder predominantly made up of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with no remaining liquid water...

 propulsion system, which offered a combination of air-independent propulsion

Air-independent propulsion

Air-independent propulsion is a term that encompasses technologies which allow a submarine to operate without the need to surface or use a snorkel to access atmospheric oxygen. The term usually excludes the use of nuclear power, and describes augmenting or replacing the diesel-electric propulsion...

 and high submerged speeds.

Background

In the early 1930s Hellmuth Walter had designed a small, high-speed submarine with a streamlined form propelled by high test peroxide and in 1939 he was awarded a contract to build an experimental vessel, the 80 ton V-80

German submarine V-80

The V-80 was a 1939 German Navy 76-ton experimental submarine and the only representative of the German Type V design.The prototype was completed in 1940 in Germaniawerft in Kiel. The 4 man vessel was designed to test the Walter hydrogen peroxide-based turbine propulsion system...

, which achieved an underwater speed of 28.1 kn (15.3 m/s) during trials in 1940. In November 1940 Admirals Erich Raeder

Erich Raeder

Erich Johann Albert Raeder was a naval leader in Germany before and during World War II. Raeder attained the highest possible naval rank—that of Großadmiral — in 1939, becoming the first person to hold that rank since Alfred von Tirpitz...

 and Werner Fuchs (head of the Kriegsmarine

Kriegsmarine

The Kriegsmarine was the name of the German Navy during the Nazi regime . It superseded the Kaiserliche Marine of World War I and the post-war Reichsmarine. The Kriegsmarine was one of three official branches of the Wehrmacht, the unified armed forces of Nazi Germany.The Kriegsmarine grew rapidly...

s Construction Office) witnessed a demonstration of the V-80; Raeder was impressed, but Fuchs was slow to approve further tests.

Following the success of the V-80's trials, Walter contacted Karl Dönitz

Karl Dönitz

Karl Dönitz was a German naval commander during World War II. He started his career in the German Navy during World War I. In 1918, while he was in command of , the submarine was sunk by British forces and Dönitz was taken prisoner...

 in January 1942, who enthusiastically embraced the idea and requested that these submarines be developed as quickly as possible. An initial order was placed in summer 1942 for four Type XVIIA development submarines.

Construction

Of these, and , designated Wa 201, were built by Blohm & Voss, commissioned in October 1943, and achieved 20.25 kn (11 m/s) submerged. The other pair of Type XVIIA submarines, and , designated Wk 202, were constructed by Germaniawerft and commissioned in April 1944.

The U-793 achieved a submerged speed of 22 kn (12 m/s) in March 1944 with Admiral Dönitz aboard. In June 1944 the U-792 achieved 25 kn (13.6 m/s) over a measured mile.

The Type XVIIA submarines were found to be very hard to handle at high speed, and were plagued by numerous mechanical problems, low efficiency, and the fact that a significant amount of power was lost due to increased back pressure on the exhaust at depth. Also, the length to beam ratio was too high, resulting in an unnecessarily high drag.

Admiral Fuchs argued that introducing a new type of U-boat would hinder current production efforts, but Dönitz argued the case for them and on 4 January 1943 the Kriegsmarine ordered 24 Type XVII submarines.

Construction of operational Type XVII submarines - the Type XVIIB - was begun at the Blohm & Voss yard in Hamburg

Hamburg

-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

. The Type XVIIB, unlike the XVIIA, had only a single turbine. The initial order was for 12 submarines, U-1405 through U-1416. However, Blohm & Voss were already struggling to cope with orders for Type XII submarines and the Kriegsmarine reduced the order to six.

Projected types

Twelve Type XVIIG of slightly improved design, U-1081 through U-1092, were at the same time ordered from Germaniawerft, Kiel

Kiel

Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

.

A projected Type XVIIK would have abandoned the Walter system for closed-cycle diesel engines using pure oxygen from onboard tanks.

Completed boats

Three Type XVIIB boats were completed by Blohm & Voss

Blohm + Voss

Blohm + Voss , is a German shipbuilding and engineering works. It is a subsidiary of ThyssenKrupp Marine Systems; there were plans to sell 80% of Blohm + Voss to Abu Dhabi Mar Group, but talks collapsed in July 2011.-History:It was founded on April 5, 1877, by Hermann Blohm and Ernst Voss as a...

 of Hamburg

Hamburg

-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

 between 1943 and 1944: , and . U-1405 was completed in December 1944, U-1406 in February 1945, and U-1407 in March 1945.

A further three boats (U-1408 to U-1410) were under construction, but were not complete when the war ended. Another six Type XVIIB's (U-1411 to U-1416) were cancelled during the war in favour of the Type XXI

German Type XXI submarine

Type XXI U-boats, also known as "Elektroboote", were the first submarines designed to operate primarily submerged, rather than as surface ships that could submerge as a means to escape detection or launch an attack.-Description:...

.

Post war

All three completed Type XVIIB boats were scuttled by their crews at the end of the Second World War, U-1405 at Flensburg, and U-1406 and U-1407 at Cuxhaven, all in the British Zone of Occupation. U-1406 and U-1407 were scuttled on 7 May 1945 by Oberleutnant Gerhard Grumpelt even though a superior officer, Kapitän zur See Kurt Thoma

Kurt Thoma

Kapitän zur See Otto Kurt Thoma was a Knight's Cross of the Iron Cross recipient during World War II...

, had prohibited such actions. Grumpelt was subsequently sentenced to 7 years imprisonment by a British military court.

At the Potsdam Conference

Potsdam Conference

The Potsdam Conference was held at Cecilienhof, the home of Crown Prince Wilhelm Hohenzollern, in Potsdam, occupied Germany, from 16 July to 2 August 1945. Participants were the Soviet Union, the United Kingdom, and the United States...

 in July 1945 U-1406 was allocated to the US and U-1407 to Britain and both were soon salvaged. The uncompleted U-1408 and U-1410 were discovered by British forces at the Blohm & Voss yard in Hamburg.

The United States Navy did not repair and operate the U-1406 as it had with the two Type XXI submarines

German Type XXI submarine

Type XXI U-boats, also known as "Elektroboote", were the first submarines designed to operate primarily submerged, rather than as surface ships that could submerge as a means to escape detection or launch an attack.-Description:...

 it had captured. She travelled to the US as deck cargo, having been stripped after being damaged by fire and twice flooded. Portsmouth Navy Yard estimated it would cost $1 million to put her into service, but plans to do so were rejected due to the perceived fire hazard and high cost of HTP and she was broken up in New York harbour sometime after 18 May 1948.

The Royal Navy repaired the U-1407 and recommissioned her on 25 September 1945 as . She served as the model for two further HTP boats, and .

List of boats

Type XVIIA

Wa 201 - Blohm & Voss, Hamburg

Wk 202 - Germaniawerft, Kiel

Type XVIIB - Blohm & Voss, Hamburg
- scuttled May 1945, raised, and transported to the US, broken up sometime after 18 May 1948 - scuttled May 1945 - scuttled May 1945, raised, repaired and served as until 1949

• U-1408—U-1410 - incomplete when the war ended
• U-1411—U-1416 - contract cancelled before construction began