# A question regarding the cannon on top of submarines **URL:** \ **Category:** Factual Questions\ **Created:** [March 10, 2003, 11:16pm UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431 "2003-03-10T23:16:36Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [March 11, 2003, 6:47pm UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/21 "2003-03-11T18:47:07Z")
I seem to recall that the Japanese build some enormous submarines, which mounted large-calibre deck guns and carried seaplanes! From what I read, these big boats were not of much use…but they sure had a great range. What was the largest pre-nuclear submarines? ---
**Author:** ![Doc\_Nickel](https://avatars.discourse-cdn.com/v4/letter/d/5fc32e/32.png) [@Doc\_Nickel](https://boards.straightdope.com/u/Doc_Nickel)\ **Post date:** [March 11, 2003, 7:01pm UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/22 "2003-03-11T19:01:49Z")
Actually they weren’t all that large. The plane- singular- was disassembled and stowed in a special compartment. The plane itself was pretty small too- I forget exactly, but I seem to recall it was a small recon type, not a fighter, equipped to carry only one or two small bombs. I get the impression it was the size of a large Cessna. When launching, the crew hauled out the fuselage, attached the floats and wings, set it in the water and the pilot took off like any normal small seaplane. ---
**Author:** ![Sofa\_King](https://avatars.discourse-cdn.com/v4/letter/s/58956e/32.png) [@Sofa\_King](https://boards.straightdope.com/u/Sofa_King)\ **Post date:** [March 11, 2003, 7:26pm UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/23 "2003-03-11T19:26:20Z")
I think that the planes the Japanese usually used via submarine were [Yokosuka E14Y](http://www.pacificwrecks.com/resources/tech/aircraft/glen.html) float planes which the Allies called “Glen.” They were primarily reconaissance, but one did try to start a forest fire in Oregon. However, at the close of the war the Japanese were developing a larger float plane with which to attack the Panama Canal with adult-sized bombs, the Aichi M6A1 Seiran. The [Paul E. Garber](http://www.si.edu/opa/researchreports/9995/seiran.htm) facility has one and is working to complete its restoration. ---
**Author:** ![sqweels](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@sqweels](https://boards.straightdope.com/u/sqweels)\ **Post date:** [March 11, 2003, 10:12pm UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/24 "2003-03-11T22:12:13Z")
> [@](#): > > A gun has rifling and fires a shell, a cannon has no rifling and fires a cannon ball. And yet rapid fire weapons of 20mm-40mm caliber are called “cannon”. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [March 12, 2003, 6:25am UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/25 "2003-03-12T06:25:06Z")
Probably not officially. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [March 12, 2003, 6:59am UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/26 "2003-03-12T06:59:09Z")
U.S. Navy (DoD) definition of [gun](http://www.dtic.mil/doctrine/jel/doddict/data/g/02349.html) (note that it is defined as a _type_ of cannon. The definition of _gun_ is contrasted with the definitions of [howitzer](http://www.dtic.mil/doctrine/jel/doddict/data/h/02478.html) and [mortar](http://www.dtic.mil/doctrine/jel/doddict/data/m/03465.html). There is no separate entry for _cannon_ or for _machine gun_ (which would be useful, for those not already aware of it, in distinguishing between a 20 mm cannon and a .50 caliber machine gun) or for _rifle_ (which is another Navy term for the long-barreled cannons that replaced the older smoothbores). ---
**Author:** ![ChalkPit](https://avatars.discourse-cdn.com/v4/letter/c/a88e4f/32.png) [@ChalkPit](https://boards.straightdope.com/u/ChalkPit)\ **Post date:** [March 12, 2003, 7:43am UTC](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431/27 "2003-03-12T07:43:14Z")
**sqweels** , that was the naval definition. I found that cannon and gun would be used to describe the same weapon in the same sentence, it’s just a case of what’s the official designation I suppose. The difference between a cannon and machine gun is somewhat simpler. As a general rule: Cannon fire shells which explode, machine guns fire bullets, which do not. Different services define the various weapons slightly differently, but that topic would hijack the OP even further. [Previous page](https://boards.straightdope.com/t/a-question-regarding-the-cannon-on-top-of-submarines/160431.md?page=1)