What is this deck fitting?

[HUAX]

Hello,

  I'm working on a set of plans for HMS Glen Avon, which I'm sure you knowledgeable people are aware was a passenger PS commissioned as a mine sweeper in WWI and then again as an anti-aircraft ship in WWII.  I'm drawing up plans for its WWII arrangement; there are a few good photos out there on the internet, and of her sister ship, HMS Glen Usk, but one deck fitting is proving a problem to identify:

Here's a 3/4 view of HMS Glen Usk: https://www.clydeships.co.uk/files/201403180814500.GLENUSK1914.jpg
Just aft of the sponsons, there's what looks like a square-barreled anti-aircraft gun, pointing almost vertically, amidships.  No listing of the armament of these vessels (sometimes referred to as Eagle Ships, possibly after HMS Eagle?) describes whatever this gun is, if it is a gun.

Here's a 3/4 view of HMS Glen Avon: https://www.wrecksite.eu/img/wrecks/glenavon_hms.jpg
The square-barreled weapon is here at a lower elevation.  This is a bit of a confusing picture - the grey wedge to the left of the mystery weapon is the raised section of the forward round armoured gun position (tub) on the port sponson, I think.

Here's a starboard view of HMS Glen Avon: https://images.squarespace-cdn.com/content/v1/5c65dd81af46834afd07e40a/1613239192381-IEMIDZEVTDA7TFP8IV2I/hms+glen+avon.PNG?format=2500w
The mystery weapon is above the liferaft, at the aft of the sponson.

Here's quite a nice water-colour of HMS Glen Avon setting off on patrol: https://www.shipsnostalgia.com/media/glen-avon.478008/
The artist shows the mystery weapon as some sort of enormous turret with its barrel pointing aft.

So, my question is - what is it?

Armament I've read was fitted, but that I think it probably isn't includes:
https://en.wikipedia.org/wiki/QF_3.7-inch_AA_gun - the barrel looks too long and whatever's fitted to the PS AA ships seems to have a double barrel.
https://en.wikipedia.org/wiki/QF_4-inch_naval_gun_Mk_XVI - only seems to have been fitted to much larger vessels.
https://en.wikipedia.org/wiki/QF_2-pounder_naval_gun - this is fitted everywhere else (apart from the MG positions and the forward deck gun) and is obviously smaller with a different barrel shape.

I suppose it doesn't really matter, but it'd be nice to get my plans right - any knowledge shared would be much appreciated.

Thanks!
HUAX

[derekwarner_decoy]

Welcome HUAX

I am sure you are correct, as the hull of the Glen Avon could not accommodate a 3.7" QF, or a 4"QF gun mount

The images you show of the Glen Avon for war service are I believe fitted with aft facing Bofor 40/60 single gun mounts of the Revision  as at the time...I have included an image and a link to the detail of a more recent 40/60 mount

The fwd mount is larger, could be the QF 2 Pounder "

My reference for comment is my previous employment as an Above Water Weapons Forman for our Garden Island Naval Dockyard in Sydney........and these 40/60's were repaired in my Group....[my role was Missile Launchers & [larger] Gun Mounts]

Sorry, but I do not have any answer to your original question

Derek

[HUAX]

Hi Derek,

  thanks for your thoughts and for the info on the bofors weaponry - all very helpful!

  I've been looking or other auxiliary PS AA ships (there were a surprisingly large number!) and have come across HMS Aristocrat:

https://scontent.fman7-1.fna.fbcdn.net/v/t39.30808-6/305198170_4847760998658720_9147875010694314560_n.jpg?_nc_cat=103&ccb=1-7&_nc_sid=5f2048&_nc_ohc=N9PcfGBqjv4AX-dPMTI&_nc_ht=scontent.fman7-1.fna&oh=00_AfAuq_lCMcfQI4_gsnByetEUXy5ejX4lHq5XulfZmtjt9A&oe=65651A21

  This ship (ex DEPV Talisman, notable for diesel electric propulsion - problematic, apparently) seems to have the same strange, square weapon on its aft upper deck.  There's a book written about this one, which might contain details of the AA armament fitted, so if I really can't live without knowing, I can always stump up 9.00 and buy it, I suppose...

Thanks for your help!
HUAX

[HUAX]

Goodness me, it's a small World, isn't it?

I carried on looking for detail on HMS Aristocrat and came across this:

http://www.paddleducks.co.uk/smf/index.php?topic=2490.0

...a post from this forum, between yourself, Derek, and a chap, Nordrand, who served aboard this very ship during the war!  I wonder if he's still alive?  He'd have to be about 100 years old now, if he was 18 or so during the war...

So much knowledge seems to have been lost in the last 20 years...

HUAX

[HUAX]

...so I bought the book;

"HMS Aristocrat: A paddler at war"
Alan Brown & Richard Polglaze
Published by Waverley Excursions Ltd
ISBN 095051778

I haven't read it all the way through, yet, but it's an interesting account of war aboard an auxiliary vessel and all the unusual duties it was set to (salvaging a part-sunken DUKW, for instance!).

Anyway, at one point, the author says, "When I joined the ship the for'd Boulton & Paul turret had been relocated roughly in the same spot as the rocket launcher, which had been removed."

I started looking for WWII AA rocket ordnance, then, and found out about Z-Batteries, which was something new to me!

I can't tell who runs this, but the Royal Artillery (1939-45) website is a very well organised library of useful info, which includes this page:

https://ra39-45.co.uk/guns-equipment/projector-3-inch-z-battery

Scrolling down, one finds the Mk1, 3" Projector:

(apologies for the hotlinking - poor form on my part!)

This is very much what the mystery turret looks like, so I'm going to say that this mystery is solved.

Best regards,
HUAX

[derekwarner_decoy]

Interesting HUAX, I had no idea that such rocket ordnance existed.............. Derek