British Type 170B and 174 sonars

[STURM]

In the 1970's a number of RN ships and ships that were made in the U.K. for export, were fitted with hull mounted Type 170B and Type 174 sonars, which were linked to the LIMBO mortar. Does anyone know if these 2 sonars were fitted in a common dome and why there was a need for 2 hull mounted sonars? Thank you.

 

[ASSAIL]

In the 1970's a number of RN ships and ships that were made in the U.K. for export, were fitted with hull mounted Type 170B and Type 174 sonars, which were linked to the LIMBO mortar. Does anyone know if these 2 sonars were fitted in a common dome and why there was a need for 2 hull mounted sonars? Thank you.

As far as I remember, and without any resort to BR's they were in separate domes.
Type 170 was the attack beam (10degs IIRC) sonar and 174 or Sword was a depth (slant range) type.
174 was not fitted into RAN Type 12's but were last used in the Battles. I was a Cadet Mid in ANZAC and we used 174 to navigate through uncharted passages of the Great Barrier Reef in the 60's
Cheers

On the other hand that 174 could have been sonar 147?

Bad case of late nightess or foot in mouth! Just checked and 174 was the precurser to the sonar type 177.

 

[STURM]

If I'm not mistaken, the Type 147 was used for depth sounding and were fitted on the RNs Type 16s. A possibility is that of the Type 170 and 174, one was passive and one was active/passive. The Type 21s had 3 sonars, a Type 170, a Type 174 and a Type 162. A bit confusing isn't it .

 

[ASSAIL]

If I'm not mistaken, the Type 147 was used for depth sounding and were fitted on the RNs Type 16s. A possibility is that of the Type 170 and 174, one was passive and one was active/passive. The Type 21s had 3 sonars, a Type 170, a Type 174 and a Type 162. A bit confusing isn't it .

Type 170 was a narrow beam attack sonar usually associated with Mortar MK 10.
Types 174/177 were medium range search sonars.
Type 162 was a bottom classification set which, a little like a depth sounder that gave an image of a sub (shadow areas on a paper recorder)if you passed directly over it.

Sonar 147 was used in conjunction with Mortar Mk 3 and calculated slant range as its primary function, could be used in much the same way that modern forward looking depth sounders are used.
Now you have really started to blow a few cobwebs loose from my past!
Cheers

 

[Abraham Gubler]

The book "A Critical Vulnerability: the impact of the submarine threat on Australia's maritime defence 1915-1954" by David Stephens has an appendix detailing all of these early sonars (up to 177) and other ASW weapons. You can download all 400 pages at:

http://www.navy.gov.au/w/images/PIAMA15.pdf

And yes Assail is right in his summaries!

Cut and paste:

368 A CRITICAL VULNERABILITY
Type Introduced Vessels Remarks
in RN
147B 1943 Battles, An active high frequency, short range, low
Frigates. powered depth finding set used with Type 144
and Squid. The RN’s most sophisticated WWII
A/S weapon system.
147F 1947 Battles, Improved depth recorder, more powerful
Tribals (mod), transmitter and improved transducer and
Frigates (mod), ‘sword’ for use against very deep
Darings (interim). conventional submarines (1500 ft).
149 1944 Melbourne Passive torpedo detection set. Hydrophone on
forward shaft which was rotated continuously by
separate motor; standard quartz aft transducer.
One operator. Superseded 132.
160X 1948 Battles Expected fit only. Essentially an updated
(proposed) 144, with two quartz transducers on separate
shafts, but did not proceed beyond prototype.
162 1948 Tribals (mod), An active high frequency, short range, low
Frigates (mod), Battles, powered set for classification of bottom
Darings, ‘Q’ conversion, contacts. No operators.
Type 12s.
164 1950 Tribals (mod) An active high frequency, short range, low
Frigates (mod) powered search light set. Three operators.
Maximum detection range 3000 yds. Controlling
set for Squid. Retractable dome. Essentially an
updated 160X with better bearing recorder and
more efficient steering arrangements.
166 1950 Darings (interim) Double set combining 164 with 174, one to be
used for echo sweeping and the other as a
hydrophone. The aim was to pick up a fast
submarine making loud HE.
170 1952 Darings (final), An active high frequency, short range, low
‘Q’ conversion, powered search light set. Three operators.
Type 12s Controlling set for Limbo. Retractable dome. Attack
set.
174 1951 Darings (final) An active high frequency, short range, low
‘Q’ conversion powered active or passive searchlight set.
Type 12s (interim) Two operators. Modified version of 164.
Used as secondary listening set for 170 in some
ships. Same dome as 170.
176 1952 Type 12s (final) High frequency passive scanning set for
torpedo detection. One operator. In lieu of 174 in
some ships. Same dome as 170.
177 1956 Type 12s (final) An active low frequency, medium range, high
powered search-light set. Three operators.
Median detection range 4500 yds but capability
to 20,000 yds. Fitted in own retractable dome.
Sources: Hackmann, Seek & Strike; Paper, ‘HMA Ships in Commission and Operational
Reserve, 1970’, NHD Canberra; various archival sources.

 

[STURM]

Thanks for the help guys. That's the great thing about DT, no matter how obscure your question is, there's always someone who can help!

Have another question. Instead of opening a seperate thread, I thought I'd ask it here.
When a hull mounted sonar is removed from a ship and is not replaced with another, is the dome normally left in place or is it also removed? And if the dome is removed or sliced off, can the opening/gap in the hull be welded or does a new frontal hull section have to fitted to the hull?

 

[ASSAIL]

Thanks for the help guys. That's the great thing about DT, no matter how obscure your question is, there's always someone who can help!

Have another question. Instead of opening a seperate thread, I thought I'd ask it here.
When a hull mounted sonar is removed from a ship and is not replaced with another, is the dome normally left in place or is it also removed? And if the dome is removed or sliced off, can the opening/gap in the hull be welded or does a new frontal hull section have to fitted to the hull?

I'm not sure why a serviceable ASW ship would remove its Sonar unless, for some obscure reason there was a total role change.
Having said that, there are various types of "domes", "hull outfits". The most recognisable are the huge 20 tonne plus low frequency sonars often found on the bow which give the "bulbous" bow look. If the sonar transducer was removed from these it would probably be most cost effective to simply ballast the bulb to the same weight as the removed transducer.
Another type of hull outfit is a retractable dome usually sighted about 1/3 ships length back from the bow (to reduce water disturbance). These could be easily removed and welded shut as the effect on longitudinal stability is negligable.
Cheers

 

[localhost127]

could anyone recommend any books on passive/active sonar sensors/suits/arrays/etc for a hobbyist?

lots of wonderful references out there on radar, but now i'm looking for something geared towards sonar.

thank you,

 

[STURM]

I'm not sure why a serviceable ASW ship would remove its Sonar unless, for some obscure reason there was a total role change.

Thank you for the feedback. The reason I asked the question is because I have been doing some research on an RMN ship, KD Hang Tuah [the former HMS Mermaid]. As part of a refit in 1997, to serve as a training ship, she had her sonars removed. They were no longer operable due to old age and a lack of spares. It got me thinking of whether on no the dome was left in place or was removed.