Hi. I'm building an old Matchbox 1/72 Flower and I can't find any data about the shape or position of the Mk 123 ASDIC dome which these ships had.

This feature always seems to be missing on kits, but it would be quite obvious in real life. Even the full-size Sackville re-creation does not seem to have a dummy dome.

The best ASDIC site on the web seems to be http://jproc.ca/sari/asd_et2.html , which shows a Mk 144Q dome, but this will not be the same as the Mk 123 non-retractable dome.

Hello, mate, and
Welcome to Model Shipwrights!

Great question, and I'll do my best to help ya out, but right now I'm at the office, and my library is at home. . .give me til after quitting time, and I may be able to help you out!
Cheers!
~Gunny

Hey Dodgy,
In the meantime, have you seen this website of Flowers? It's quite extensive and very concise. . .
Flower Class Corvettes

Yes, I have been to the cbrnp site, and, I suspect, most others on the web!! I picked up this original Matchbox kit at a summer fete for a few quid and found it missing the main deck and rear superstructure, so I have been looking at kit pictures to find where to place the deck items. You can see a bit of what I was doing here - http://www.rcgroups.com/forums/showthread.php?t=473188&page=6&pp=15

Thanks for the welcome and the offer, Gunny. Your research work on the sweeps was first-class. The problem seems to be that ASDIC was a highly classified subject during this period, and photos of anything associated with it are going to be rare. But Flowers are such a well-modelled subject that I had hoped someone would have asked this question before me. It's beginning to look as if I am the first

Hello, mate!

Nice work on the Flower so far! I'm going to ask the obvious, though, is she going to be RC?

I've searched through every related volume and have come up with text and reference info, but no pics, or even any detailed description that may help. . .but I'm not giving up yet!! (I can be quite tenacious, my friend! )
Gimmee a bit more time to see what I can dig up!

~Gunny

Welcome aboard !!!

I have quite a bit of Flower info & never even thought about it.

The plan sets I have indicate it would be approx 3-1/2 feet forward of a line drawn down thru the main gun pedestal. I am unsure if it is mounted on center or offset. I know little else about it.

When I get around to the 1/48 Flower (R/C) & the 1/72 Flower (w/all the GLS brass), I'll have to get more serious about that detail ...

Hope my one piece of info helps ...
John

BTW, the book "The Flower Class Corvette Agassiz", by McKay & Harland is an invaluable reference,

Another little "piece" of info for ya--- the Asdic Dome on the Flower Class Corvettes was located between the bridge and the forward gun, on the bottom of the ship and offset to starboard from the keel.

The dome was semi-circular in shape and could be retracted into the hull. This was I was told in the RCN. but precisely which mark/model this referred to, I don't know.

As other posters have said, this was highly "classified" information during WWII and was being constantly modfied.

It still may be difficult to find this information as when I joined up in 1964 the sonar and radar rooms were "off limits" to anyone not a radioman or sonar rating......!

I'll see what I can find out through some of my "sources"....Good Luck!

(And yes, Bravo Zulus to Gunny for the sweeps info!!)

Thanks for the help. Gents!
I'm still trying to locate a usable photo/diagram for our man to use, but not much luck. . .still going, though!
~Gunny

Thanks for all the info, folks. We still don't have a definitive photo, though. It may well be the case that so many different Flowers had so many different fits throughout their lives that almost anything would be appropriate.

Though the boat is for R/C, I had never intended it to be fully scale. My main interest is in slope soarers. I just could not let it sit there on the stall and be junked at the end of the day! I was originally intending to build it out-of-the-box, but when I looked at the mould design for the Oerlikons I could not put up with that, and then checked on the rest of the weaponry. That was when I noticed the ASDIC dome was missing. It's not much smaller than the radar, and just as important to the ship's operation, so I thought it should be there.

Dome shape:

The Proc site gives it as 'covered with steel fairing plates', and the only pictures we have for the 144Q dome show it as a symetrical elliptical protrusion. Interestingly, the same shape is shown at this site http://www.de220.com/Electronics/Sonar/Sonar.htm where it is designated as non-retractable, and is probably a different mark. I suspect this long shape is needed to enclose the 'Sword' transducers which gave a tight directional beam, and which, of course, the Flowers would not have had (or did some of them?). I can well imagine that the early domes without Sword would be semi-circular, but that would give turbulence unless the ship was stationary. Of course, the original U-boat threat was around harbours, so a slow or stationary patrol craft might be quite a reasonable plan. And the turbulence would mask the view behind, but that would be off-limits due the the propellor wake anyway, so it might not matter. It might be worth streamlining the dome a bit to reduce drag, especially if it were non-retractable.

From this I guessed that the Mk. 123 domes might be semi-circular, then faired to a teardrop shape.I feel pretty sure the Flower domes were non-retractable. I think I can remember stories of crews having to remove the dome before proceeding up river. Proc certainly gives the 123 dome as non-retractable.

Dome position:

The Proc site implies that the dome was directly below the ASDIC hut, which was just in front of the bridge. This is in agreement with Killick's view that the dome was between the bridge and the forward gun. I would be suprised to find that it was as forward as JRatz's plans put it - there is very little hull there and it would be in danger of breaking surface in heavy seas. It would have to be centre mounted there, and would be the first thing to break in a ramming attack. I think we have stories of corvettes using their ASDIC after several ramming episodes? I would love to see a copy of the relevent portion of the plans to understand what he is proposing.

I had initially thought that the dome would be offset. The Flowers were simple ships built to a basic design, and any non-standard keel fabrication would cause problems in a small shipyard. But if the domes were non-retractable, I suppose they could be bolted on anywhere later. Proc implies that the 123 domes were centre-mounted when he says "The dome was fixed to the bottom of the keel with heavy nuts. " . The Flowers did not have an external keel in spite of what the Matchbox kit shows. The problem is that Proc may well mean 'hull' by 'keel'? I think that later he says 'understatement' when he means 'overstatement'.

Based on the above arguments I was going to put a teardrop-shaped dome in place, central, somewhere in the mid-forward portion of the hull. You can see a picture of the shape I have so far here, http://www.rcgroups.com/forums/showthread.php?t=591436 though I have stopped work while this discussion proceeds.

If you go to the Sirmar Model Ships website at http://www.sirmarmodelships.com/showship.asp?ID=38
---you'll find that they offer an "Asdic Dome" for their 1942 Bangor Class Minesweeper (Fittings Package #1).....Sirmar Models are exhaustively researched and designed to "museum standard" .

The Bangor Class Minesweeper was used extensively by the RCN during WWII --and one of the first things the Canadians did was "chuck the Sweep gear on the jetty" --as these sweepers were used for the most part as Anti-Submarine vessels.

Yes, Asdic domes were quite commonly damaged if a U-Boat was rammed by almost ANY ship that was fitted with one.....A ship the size of a Corvette was almost the same size as a U-Boat and would "ride up over it's deck". Didn't do much for the Corvette, either....!

Thanks - that's really useful - shame they don't show a picture of the item, and that it costs £30 to buy the pack. That's ten times the cost of my original kit!

They do show a picture of the boat with the fitting, and it looks like the large eliptical stub that we have pictures of already. Of course this is the 128 retractable dome - I suspect the 123 was somewhat different.

The picture is very helpful for illustrating the position - I would guess that the 123 was probably mounted in a similar place. It looks slightly offset (or would you say it was central?), but more forward than I was guessing. It matches the JRatz plan rather than the Proc implication. It's smaller than I was expecting - I had been planning a 5'x5'x12' shape, while this looks more like 3'x3'x5'. A non-retractable dome might be even smaller.

I was suprised at the frequency of ramming attacks against U-boats, particularly if it meant loosing your ASDIC. I would have thought a 4" shell would have done more effective damage quite reliably at point blank range. Even cannon shells would make a hole in them at that range, wouldn't they?

Interestingly, the Sirmar site also does 1/48 kits of the Agassiz and Byrony. The Agassiz fitings mentions a 'Sonar' dome while the Byrony, which must have had the same fitting in full size, does not. I would be a bit annoyed if I were buying a Byrony!

The fittings are FirstMarine, so I went there to see if I could find a picture, but the FirstMarine site does not want to work with my Opera browser, so I couldn't see everything. I suspect, however, that the 'Sonar' dome they are selling is not a Mk 123, but the same one as on Bangor, which should be a Mk 127 retractable. Still, it may look very similar?

"Ramming" was a last-ditch measure , as escorts of any kind were in short supply until late in the war. If you know the "basics" of U-Boat construction (ie, what you see is an"outer" hull , with the "pressure" hull inside) you can tell that a 4" gun could do damage to the coning tower .....but usually had little effect on the pressure hull.

(The same principle makes so effective the "spaced" armour of today)

A well-trained crew on a U-Boat's deck gun could --and some times did -- --inflict severe damage on a Corvette closing with them.....Remember, a surfaced U-Boat would sit very low in the water and the motion of a vessel like the Corvette made hitting something that low rather difficult.
(There was a limit after all to how far her gun would "depress"...!)

The Corvette's guns of course were :"manually" controlled ; although I myself never served on one, the Ols Salts who were among my instructors did --and said those ships "Would roll on wet grass!".

Good Luck in Your Searches --

"Splice the MainBrace!"

Paul.

The impression I got from a number of the reports of actions was that ramming was not thought of as a last-ditch resort, but rather something you would attempt to do if you got close to your enemy.

While a 4" shell might not penetrate the pressure hull amidships (though it would go through the bow or stern) it would surely make a mess of the main dive tanks, which should be enough to sink the U-boat?

Inability to depress the main gun would certainly be a reason for ramming. The reports I have read suggest that ramming was a typical scenario in bad weather (visibility 300 yds or less, and radar being used to engage). The corvette's light calibre weapons were used to keep the U-boat's deck gun unmanned while the corvette rammed and delivered a shallow-setting depth charge as it withdrew. With the ASDIC dome where we now think it is, unless the ram was a glancing blow, you would almost certainly loose your ASDIC capability through such an action. I don't know if the corvette bows were specially strengthened. You might also lose your propeller if you went right over the boat!

Perhaps the loss of one corvette for one U-boat was seen as a reasonable exchange?

The plans I referenced are Lambert plans. I have the Sirmar Agassiz hull and parts -- on the to-do list as I said ...

Anyway, I suspect that after ramming a U-boat, the state of the ASDIC is one of the lesser worries of a corvette crew ...

BTW, if you think going to sea in corvettes was scary, start looking at trawlers ...

John

I am building at present a 81" model of an Auxilliary Patrol Trawler. which is not equppied with Asdic --but is just about as hard to find information on ....! .

Bobslr on http://www.rcgroups.com/forums/showthread.php?t=591436#post6338740 has very kindly provided me with a couple of scans of plans showing shape and placement of the dome on the Flower and Castle corvettes.

It is situated in JRatz's position - quite far forward - and in shape is the same as the dome called 'generic' on this site: http://jproc.ca/sari/asd_et2.html . This is a copy of a drawing from this site: http://www.de220.com/Electronics/Sonar/Sonar.htm where it is described as a 'retractable sonar pod'.

So it's beginning to look as if Flowers might have had retractable pods after all. This would explain how corvettes could use ASDIC after ramming, but it would also mean that JProc's site is incorrect.

I also have difficulty with this shape being retractable - it's on a stalk which would mean a cavity would be left in the hull above it when it was deployed, creating extensive turbulence. Surely retractable domes would have parallel sides?

And I'm busy researching plans for HMT Bedfordshire, a Grimsby fleet trawler built in 1935 by Smith's Dock and requitioned into the RN as an A/S trawler, sunk off the Outer Banks 11 May 1942. I have one picture of it before requisition and one after requisition and arming. I have some Lambert plans that allow me to "interpret" the photo a bit better. Not started work yet -- it will obviously be scratchbuilt, but not 81" ... I agree, there isn't much available ...

John

First off --let me apologize: I mean to type 61", not 81"....!! Happens when you squint too long at the screen....

I found Bedfordshire among Requisitioned Trawlers in my "Warships of WWII, Part 6" .. She's a bigger trawler than the one I'm doing, which is 311 tons, 123' LOA. Bedfordshire is listed as 443 tons, PN FY141.... According to "Trawlers Go To War", she was sunk by a U-Boat just South of Cape Lookout , only 2 months after her arrival in the States!

For my model I'm using a Dwight Hartman Hull; tt will be made into a "Strath" Class Trawler, in 1/24 scale. I've been researching trawlers since last Spring -- and if I can be of any help in that department please let me know..

Was Bedfordshire equipped with a 12-pounder gun? I have some excellent close-up photos from a Naval Museum that I'd be glad to scan and email to you....!

I haven't started building my trawler yet, either. But I also have a Hard Drive full of pictures, links, etc, that may be of some use....

I assume you've seen the picture of the (armed) Bedfordshire on "The Bosun's Watch" website?
http://www.fleetwood-trawlers.connectfree.co.uk/wartrawlers.html

Even though the Site is dedicated to Trawlers that were based in Fleetwood, the Webmaster, is very helpful when it comes to providing details for wheelhouse interiors, etc. ...!




..

You might be interested in a picture of the ASDIC domes I have made so far - I have put them up here: http://www.rcgroups.com/forums/showthread.php?t=591436#post6343745

Paul:

Yes, thank you, that armed picture is the same as I have -- the only one in existence. Is a 4" gun a 12-pdr ? My scale will be small, wheel house interiors aren't necessary, but thanks anyway.

I have just laid a grid over that photo and will start to make a drawing, using the Lambert plans for the Zeno & St Apollo to interpret the photo ...

The Bedfordshire was based at Ocracoke Island. The few bodies that washed ashore are buried there, in a cemetery administered by the Brit Graves Comm (sic). Every year there is a small ceremony attended by an RN, or sometimes RCN, representative. "Forever a small piece of England..."

John

Quite an array of shapes there; dodgy...! I really like your idea of the brass pins and "plug-in" asdic domes!

Actually John, there is a difference:. A 12-pounder Gun has a 3" bore, whereas a "4-inch gun" is a heavier gun and has (what else?) a 4-inch bore....!

!2-pounders were found mostly on Minesweeping and Auxilliary Patrol Trawlers; Anti-submarine Trawlers carried the heavier 4" gun.

There were two types of single-mounted 4-inch guns: one used a projectile and a "bag charge" , and the other --the "Quick-Firing" version-- used "fixed" ammunition. The gun in the photo of Bedforshire appears to be the QF type, which fired HE rounds, semi-armour piercing rounds, and starshell.

(There are definitely machine guns mounted on the Bridge wings, and what looks to me like a 20mm gun abaft the funnel. This would be pretty much the "standard" armament for an A/S Trawler.)

The QF 4-inch had a relatively "square" breech, very similar to what you would find on an Army 105 Howitzer , and the shell's "shape" was similar to that of a high-powered rifle bullet.

Paul.

Fascinating Discussion, mates!
Even with the lack of (so far) photos for reference, this thread has really spawned excellent discussion and coverage of this Classified subject! Thanks!
~Gunny

Looking more closely at this set of plans, http://www.history.navy.mil/photos/images/s-file/s511-30c.htm , I see that above the position where the ASDIC dome is believed to be there is an 8'x5' space titled 'sound room'.

This room seems to have a floor about 4' higher than the base of the keel, thus allowing a retractable pod to be stored there. There is, of course, no detail of the ASDIC system, but it does confirm the position, and suggests that retractable domes were at least being planned in 1941.

Paul -
Thanks for the gun info -- I would have got there sometime, so you saved me some work ...

Dodgy,
The Lambert Flower plans show that same room -- I probably should have mentioned it sooner & saved you some work. But there are no details, just a room ...

John