member, 944 posts
Mon 8 Apr 2019
at 08:08
Advice: Submarine info needed
Back in the days when submarines carried deck guns, how soon after surfacing could such a gun be fired?

Wikipedia tells me that a 3 gun could manage 15-20 rds per minute, but my Google-fu fails to find anything on the typical interval between the submarine breaking surface and the first firing of the gun - the time for the gun crew to exit the conning tower, scramble to the gun, check it, open the ammo box, load up the first round, and acquire the target.

Any figures out there? Id prefer a quote from an official source, if possible.
 member, 172 posts
Mon 8 Apr 2019
at 08:38
Advice: Submarine info needed
A quick look suggests they had a screw in plug to keep the thing dry and some maintenance requirements.

If you need an exact time you probably aren't going to find it but somewhere around 30-40 seconds seems reasonable if you don't.
 member, 326 posts
 The Doctor.
Mon 8 Apr 2019
at 09:09
Advice: Submarine info needed
I'm too lazy to find a direct answer, but you might want to take a look at


It's the Historical naval ships association page that has scanned and translated manuals from WWII era for german and american submarines.

The 1943 german submarine manual states that

The submarine as a gunnery vessel is in itself properly a contradiction in terms.

an interesting snippet from sci.military.naval

D K Brown describes his time in HMS Tabard, winning the Fleet gunnery contest: based on the tactic of surfacing close astern of the target and aiming for his stern gun, the competition started with the umpire's "Go!" at periscope depth and ended when the first shell hit the (small) target: the aim was to surface about 300 yards off the target's quarter, and strong men were picked to open the hatches as the boat surfaced: Brown estimates about a ton and a half of water would come in.

suggests it's really in the 30 second range for a prepared crew and mounting.

Also, the sub commander might want to not make the interval too short because the crew might forget to unplug the gun, with embarrassing consequences. It's happened a few times.
 member, 666 posts
 Pretty, witty, and gay
 [married since 2011!]
Mon 8 Apr 2019
at 09:20
Advice: Submarine info needed
Two Thousand Questions And Answers About The War, p.65:
Q. How quickly can a submarine's guns be housed?

A. In from twenty to thirty seconds. The Krupp rapid-fire 3-inch guns with which German submarines are armed, are so mounted that by the pull of a single lever they will turn over backward on an axle and lie snugly upside down in the well, which is then closed with a water tight, hinged cover. The time for the whole operation is 20 seconds. Some of the very latest types have, in addition to these collapsible guns, smaller deck guns, which do not need housing at all, because they are made of metals impervious to salt-water.

Based on the above quote, I can't imagine it would take more than a couple minutes to ready or secure such a gun, whether housed in the hull or mounted on deck. How long did it take surface warships to ready similarly-sized deck guns after general quarters was sounded? I suspect it ultimately depends on how well trained the crew and how well maintained the gun.
 member, 684 posts
 Wayfarer of the
 Western Wastes
Mon 8 Apr 2019
at 15:58
Advice: Submarine info needed
Everybody responding is in the ball park so far.  The biggies are:

What size and type of gun and its munitions?
What provisions for housing have been made?
Experience and training of the gun crew

Most modern submarines no longer have deck guns, so presumably you are asking about WWI or WWII submarines.  Some of the resources given are excellent for questions about US Submarines of this era, and a search there will likely find old de-classified manuals related to submarines, also.

What's the game?
 member, 945 posts
Tue 9 Apr 2019
at 05:50
Advice: Submarine info needed
Thanks folks. I've had a browse of the manuals in that link, and a couple of other places as follow-ups. No times are stated (though perhaps access to ship's logs and training records would shed some light on it) but the gunnery procedures are laid out.

However, you're all suggesting times of half to one minute, and I found an old reference that did quote a 30-40 second time to clear the deck of a U-boat and dive, so that seems a likely ball-park figure.

So, even an on-the-ball enemy couldn't put more than two or three rounds your way before you could return fire. Of course, three ranging shots might be all they need, but you wouldn't be a sitting duck for five or ten minutes.

Which is all I needed to know. Those guys were skilled and drilled!

Thanks again. :)
 member, 1543 posts
 Ocoee FL
 40 yrs of RPGs
Wed 10 Apr 2019
at 20:19
Advice: Submarine info needed
In reply to icosahedron152 (msg # 6):

Keep in mind, too, that submarines never intentionally engaged enemy fighting ships. The deck gun was intended to intimidate merchant vessels into surrendering. Even when civilian ships mounted weaponry, their crews were rarely up to military standards and most mounted one bow gun and one stern gun.

According to pre-WWI conventions, submarines were not allowed to torpedo/sink enemy merchantmen without giving them the option to surrender and abandon ship. When merchantmen began to mount deck guns and when more heavily armed Q-ships became common, this convention quickly went by the boards. Torpedo los!
 member, 947 posts
Fri 12 Apr 2019
at 04:12
Advice: Submarine info needed
Thanks Gaffer. As it happens, I knew that already, but thanks for the contribution anyway. :) This is why deck guns eventually disappeared, and submarines came to rely solely on torpedoes. There was nothing left that they could safely make a surface attack against. Subs were a lot more vulnerable to deck gun fire than the vessels they would be exchanging fire with.
 member, 1518 posts
Fri 12 Apr 2019
at 05:53
Advice: Submarine info needed
I might be able to answer this. I have a book all about subs, including old ones. It'll be a few days before I can look it up though.