Re: IJN and sound velocity profile

"Christophe Chazot" <c.chazot@xxxxxxxxxx> wrote in message
news:44526275$0$6686$8fcfb975@xxxxxxxxxxxxxxxxxx


In December 1942 or January 1943 (my sources are not very clear), the 12th
department of the Naval HQ issued a "doctrine related to the protection of
communication lanes of the great east Asia", which was the first "ASW
policy" of IJN. It was pretty irrelevant at this time but was improved
several times. In October 1944 it had become more consistent, recommending
close cooperation between aircraft and escorts and with search patterns
for
MAD-equiped and radar-equiped planes, but rather strangely it does not
mention anything about sound velocity profiles or anything close that
could
have helped omptimizing sonar operation or escorts positioning around
convoys. That's why I suspect they hardly had an idea of it. Other clues
are
that I've never heard or read anything about a dedicated bathythermograph,
that none of the numerous requisitionned crafts acted as ocean survey
ship,
and that US subs frequently noticed that IJN escorts seemed to have no
idea
of the role of temperature layers, as far as they could judge from the
reactions of escorts.
But I do not understand how IJN sub captains (or, at least, some of them)
knew that they could hide under layers. Did they learn it from their
German
counterparts ? and why didn't they inform the 12 dept.?


Chris,

Physics of underwater sound was in it's infancy in the 50's....I doubt any
WW2
Navy understood the effects of underwater sound propagation during
the war....If any Navy had a handle on it I'd say it would've been the
Brits.

Question: Have you been able to find out if any WW2 ships / submarines
even had bathythermograph's onboard?

I would argue it was the threat of the Soviet submarine force that
drove our understanding of acoustics, not U-boats in WW2, and of course
the IJN blew off ASW all together....suggesting they knew nothing of
acoustics
or underwater sound propagation.

The following quote supports the fact that Acoustics is a new science...

Mark

....[A]coustics is characterized by its reliance on combinations of physical
principles drawn from other sources; and that the primary task of modern
physical acoustics is to effect a fusion of the principles normally adhering
to other sciences into a coherent basis for understanding, measuring,
controlling, and using the whole gamut of vibrational phenomena in any
material.
Origins in Acoustics. F.V. Hunt. Yale University Press, 1978




.