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> When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical mi

> When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) I always pictured submarines would spend most of their time submerged, but how is that possible if its maximum submerged range was 92 miles? Was it really possible its surfaced range was over 100 times greater? Or was it just that it needed to surface occasionally then it could submerge again?

ralfd 7y ago
I think battery tech was the limit back then. They couldn't run the diesel motors while being submerged.
- Ididntdothis 7y ago
  I think later on they had snorkels but that still didn’t allow them to stay submerged for a long time.
jki275 7y ago
WWII Submarines were really surface ships that could dive and operate submerged for short periods of time. They weren't really submarines and weren't really designed to operate submerged. The data listed is roughly correct from what I've read.
Ididntdothis 7y ago
These submarines only dove when close to the enemy. They spent most of their time as regular ships.
jonathanp88 7y ago
You are thinking of nuclear submarines. Submarines of this era would have a bank of batteries, using 1940's technology, which they could use to run the boat whilst submerged. Once they were flat, they would have to stay at or near the surface long enough to charge them again(they could run at the surface using a 'snorkel' to bring in air for the engines. They would submerge only to attack or to hide. So looking at it from a range perspective is perhaps not the best way. They could have stayed submerged under water for a long time, but they couldn't be cruising flat out whilst doing it.
- PhasmaFelis 7y ago
  Which explains the shapes of submarines in the two eras: they're optimized for their preferred mode of operation. Diesel submarines were shaped approximately like a regular ship, with a angled and tapered prow to cut the waves. Nuclear subs are shaped like a torpedo, roughly cylindrical with a rounded prow, to move through deep water.
  - brandmeyer 7y ago
    The shift in thinking about submarine hulls occurred at about the same time as changes in propulsion, but they were separate developments. USS Albacore was the first to prototype the hull shape. A short-run class of diesel-electrics were designed to that shape before being completely overtaken by nuclear propulsion in the US. All modern submarines, including AIP, diesel-electric, and nuclear, use hull forms optimized for underwater operations.
    - rtkwe 7y ago
      There are some neat ones employed by Sweden that use Sterling engines powered by liquid oxygen and diesel which is pretty neat and makes them really quiet.
- rtkwe 7y ago
  And later in the war radar made even the semi submerged operation via snorkel pretty dangerous because the snorkels would show up on radar. If they were discovered while doing that they'd be at a pretty stark disadvantage because they wouldn't have a full set of batteries to submerge and avoid the submarine hunters.
lqet 7y ago
AFAIK, at least in WWII and for the German submarines of the VII class, the normal mode of operation was surfaced. The submarines would only submerge (go on a "Tauchfahrt") if it was absolutely necessary. Don't forget that these boats still operated with Diesel motors or on batteries when submerged. It was later possible to use the Diesel motors submerged with a snorkel [0], but this would of course only work very close to the surface. [0] https://en.wikipedia.org/wiki/Submarine_snorkel https://en.wikipedia.org/wiki/Submarine_snorkel
tsjq 7y ago
>The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines they have to come to surface to recharge the batteries and to take in oxygen.
hef19898 7y ago
Back than submarines were more like diveable torpedo boats, early in the war the still used their small deck mounted guns quite regularly. The first true subs came late during the war with the Types XXI and XXIII which looked a lot like modern Diesel-Electric subs.

ralfd 7y ago

I think battery tech was the limit back then. They couldn't run the diesel motors while being submerged.

Ididntdothis 7y ago
I think later on they had snorkels but that still didn’t allow them to stay submerged for a long time.

jki275 7y ago

WWII Submarines were really surface ships that could dive and operate submerged for short periods of time. They weren't really submarines and weren't really designed to operate submerged. The data listed is roughly correct from what I've read.

Ididntdothis 7y ago

These submarines only dove when close to the enemy. They spent most of their time as regular ships.

jonathanp88 7y ago

You are thinking of nuclear submarines. Submarines of this era would have a bank of batteries, using 1940's technology, which they could use to run the boat whilst submerged. Once they were flat, they would have to stay at or near the surface long enough to charge them again(they could run at the surface using a 'snorkel' to bring in air for the engines. They would submerge only to attack or to hide. So looking at it from a range perspective is perhaps not the best way. They could have stayed submerged under water for a long time, but they couldn't be cruising flat out whilst doing it.

PhasmaFelis 7y ago
Which explains the shapes of submarines in the two eras: they're optimized for their preferred mode of operation. Diesel submarines were shaped approximately like a regular ship, with a angled and tapered prow to cut the waves. Nuclear subs are shaped like a torpedo, roughly cylindrical with a rounded prow, to move through deep water.
- brandmeyer 7y ago
  The shift in thinking about submarine hulls occurred at about the same time as changes in propulsion, but they were separate developments. USS Albacore was the first to prototype the hull shape. A short-run class of diesel-electrics were designed to that shape before being completely overtaken by nuclear propulsion in the US. All modern submarines, including AIP, diesel-electric, and nuclear, use hull forms optimized for underwater operations.
  - rtkwe 7y ago
    There are some neat ones employed by Sweden that use Sterling engines powered by liquid oxygen and diesel which is pretty neat and makes them really quiet.
rtkwe 7y ago
And later in the war radar made even the semi submerged operation via snorkel pretty dangerous because the snorkels would show up on radar. If they were discovered while doing that they'd be at a pretty stark disadvantage because they wouldn't have a full set of batteries to submerge and avoid the submarine hunters.

lqet 7y ago

AFAIK, at least in WWII and for the German submarines of the VII class, the normal mode of operation was surfaced. The submarines would only submerge (go on a "Tauchfahrt") if it was absolutely necessary. Don't forget that these boats still operated with Diesel motors or on batteries when submerged. It was later possible to use the Diesel motors submerged with a snorkel [0], but this would of course only work very close to the surface. [0] https://en.wikipedia.org/wiki/Submarine_snorkel https://en.wikipedia.org/wiki/Submarine_snorkel

tsjq 7y ago

>The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines they have to come to surface to recharge the batteries and to take in oxygen.

hef19898 7y ago

Back than submarines were more like diveable torpedo boats, early in the war the still used their small deck mounted guns quite regularly. The first true subs came late during the war with the Types XXI and XXIII which looked a lot like modern Diesel-Electric subs.