How Deep Can A U-Boat Dive? | LakeWizard

U-boats are well-known superheroes in the naval history of Germany. Have you ever wondered how deep these boats could dive as compared to modern submarines?

Both World Wars featured the dramatic annihilation of enemy ships by German U-boats. History says these boats used to pop out of nowhere and destroy the naval vessels of adversaries in minutes.

Resources say that U-boats were able to dive to a depth of approximately 197 feet on average. But certain examples have been quoted in the historical literature that proves they were able to dive as deep as 300 feet without getting damaged, with a maximum theoretical range of 600 feet.

Due to their strong metallic hulls, U-boats were able to survive high water pressure. Although they were not as strong as today's submarines, their strength was remarkably high despite a lack of technological advancement.

We have explored some historical records and journals to collect complete information on the performance of U-boats. Here's what you need to know.

Table of contents


What were the Different German Submarines?

An official navy website of the US Naval History and Heritage Command has disclosed a pamphlet named "German Submarines in Question and Answer". This pamphlet, which was originally published in 1918, discusses some features of German submarines and how they used to work.

According to this pamphlet, there were four major types of German submarines that were operated at the time of the World Wars.

  1. Cruiser submarines, including converted mercantile class or Deutschland class submarines
  2. U-boats
  3. U.B. type boats
  4. U.C. type boats

What Do You Mean by a U-boat?

The U-boat which was previously known as a Unterseeboot is a type of German submarine. The term "Unterseeboot" means "Underwater boat". German naval forces utilized these submarines to target military and commercial ships during the first and second World Wars.

Although German forces frequently employed U-boats in the past, they are no longer operational. There are now only four U-boats that have been kept for museum purposes. These preserved boats are the only remaining symbols of the Battle of the Atlantic. They serve as a reminder of the thousands of sailors who perished during times of war in these.

How Deep Can a U-Boat Dive?

All German submarines, including U-boats, have a test depth of roundabout 197 feet. They used to operate at this depth under normal circumstances when there was no danger around. Usually, they didn't choose locations where the depth was greater than 164 feet for laying on the bottom.

The maximum operating depth of U-boats recorded during wartime was more than 200 feet. But they could dive even deeper for shorter periods of time. Many examples have been quoted in naval history that show U-boats diving to a depth of 300 feet without collapsing during battle times.

U-boats used during World War II had a crush depth (or collapse depth) range of 660 to 920 feet, whereas many modern nuclear attack submarines have a crush depth of 2400 feet.

How Long Does It Take A U-Boat To Dive Underwater?

In a U-Boat with two diesel engines, the periscope could be reached in approximately 1 to 1.5 minutes after receiving the diving signal. Even less time will be needed for U-boats with both an electric engine and a diesel engine to dive to the periscope. If the U-boat dives deeper, the time to descend to one foot will be one second.

How Far Can a Submerged U-boat Go?

Most of the German submarines, including U-boats, could be taken to a distance as far as 75 miles when submerged in water. In the event of an emergency, some U-boats could travel 100 miles when submerged in water.

How Long Will a Submerged U-boat Run?

The time for which a submerged U-boat is able to run underwater depends upon its speed. It could run for only a short period at maximum speed, for about one to two hours. However, low speeds allowed the boat to run for longer time spans, up to 2 days. In the event of a battle, a U-boat could stay submerged for up to 2 hours at a speed of 8 nautical miles per hour.

It could stay underwater for 12 hours at the speed of 5 knots, up to 24 hours at the speed of 4 knots, or a maximum of 48 hours at the speed of 2 knots.

The high speed means more expenditure on fuel. Therefore, a U-Boat would run at low speeds during battle times to avoid running its batteries down. Before it ran out of batteries, it had to recharge by surfacing atleast once. Recharging was done using a diesel engine when the vessel surfaces. In normal circumstances, a U-Boat did not remain submerged in water for more than 12 hours. It did so only when the weather was not good or when it was being chased continuously.

Dimensions of a U-Boat

Most of the U-boats were 210 to 225 feet in length, 20 to 22 feet in width, and, in surface trim, drew 11 and a half to 12 feet. These submarines used to operate at a maximum speed range of 14 to 17 nautical miles per second when on the surface and at 8 to 10 knots when submerged.

Other Characteristics of U-boats

Some other features of a standard U-boat are:

  • Carries one to two 22-pounder aft torpedo tubes
  • Flat and long deck rising toward the bows
  • A straight stem
  • Conning tower in between the ship's bow and stern
  • Two prominent cannons are mounted, one before and one after the conning tower
  • A net cutter near the bow
  • Carry a total of 8-12 torpedoes

What are the U-mine layers?

U-mine layers belong to a unique class of U-boats. These are single-hulled boats moving at relatively lower speeds. These were initially 10 in number, from U 71 to U 80. U-mine layers were able to carry 36 mines and 2 torpedoes. Only five of the U-mine layers had been left during 1918 because these submarines had not been effective.

Effect of Explosions on U-boats

Any explosion, including attacks through torpedoes in the vicinity, could cause serious damage to the U-boats. Some of these damaging effects can be seen in the following forms:

  • A serious leak led to the immediate sinking of the boat.
  • If a hatch buckled, a leak would result because the pumps would be unable to stop, ultimately forcing the vessel to surface.
  • The exterior tanks developed a leak. It could cause a significant loss of fuel due to spillage.
  • The bases of the on-board periscopes were rattled or broken, which would potentially require the boat to be brought back.
  • The boat could be brought to the surface of the water or be forced to plunge to a catastrophic depth if the hydroplanes are pushed hard up or down.
  • The boat may be shaken vigorously by the exposure
  • Cutouts fused, causing the electricity to go out as a result. In such cases, the boat didn't typically sink or float, but the impact on the crew was quite significant.