Re: Why so few U-boats at the start of the war?

In article <w_Lqj.31416$R55.15896@xxxxxxxxxxxx>, rsveinsn@xxxxxxx
(Robert Sveinson) wrote:

I am assuming that you are referring to "the
happy time" before mid 1943 as
ASDIC was developed during WW I and was
available to the navies at the beginning of WW II.


Confusing two different things here. The hydrophone was developed
during WW1 and was a passive listening device. Echo location, ASDIC was
developed between the wars coming into service 1938-39.

The first "Happy Time" was 1939-1940 before RADAR and before the Convoy
system was fully established.

ASDIC was capable of detecting submerged submarines
and not completely submerged iceberg.

Range was limited something like 800-1000 yards in 1939 IIRC. It helped
a lot if you had some idea of where the submarine was either from
torpedo tracks or seeing it submerge. Off course a surfaced submarine
could not be detected by ASDIC.

Before radar equipped escorts became common the German tactics of
attacking on the surface at night made a lot of sense.

The lost contact problem was reduced
when the Hedge Hog was used,

Nope it was solved because Hedgehog was a forward throwing weapon. When
depth finding sonar was added Squid came into use and that was time
fused. Contact was lost because most WW2 active sonars had only one axis
of rotation which meant that the vertical angle of the beam was fixed.
This produced a blind spot centred on the ship with a diameter that
depended on the submarines depth. To get an effective depth charge
pattern the ship had to fire as it was passing over the estimated
position of the sub after allowing for the charge sink rate.

This meant that contact was lost before the pattern could be fired.
With Hedgehog or Squid there was enough range that they could be fired
before contact was lost. Before the ahead throwing weapons if enough
escorts were available it was common for one ship to carry out a depth
charge attack while a second maintained contact with the sub and updated
the first on target position.


Ken Young

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