Joined: 11:25 AM - Jan 07, 2005

2:06 PM - Aug 10, 2018 #11

RAN Freemantle class had an 81mm mortar for the first half of their lives. Exactly why, and how often it was exercised is another question
"The stone age did not end because people ran out of stones." Ahmed Yamani
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Joined: 4:04 PM - Jan 14, 2013

2:15 PM - Aug 10, 2018 #12

From photos its looks like the Fremantle mortar was mounted on the stern without a gun shield or other special mounting.  Kind of hard to tell.
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Joined: 7:48 PM - Apr 10, 2006

2:17 PM - Aug 10, 2018 #13

Hark wrote: That's a nice installation for AMOS.  I've wanted the US Marines to try out this system on an armored vehicle.  Its perfect for what they do.
The USMC has taken a different route: their standard 120mm mortar, the M327, has a rifled barrel and fires spin-stabilised rounds. I can't see them adopting an entirely different 120mm mortar system using different ammo.


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M2
Joined: 12:22 PM - Aug 24, 2009

2:21 PM - Aug 10, 2018 #14

Actually hitting something with 81mm mortar that is not stabilized is not easy.

Stabilized NEMO Naval mortar system is in service in United Arab Emirates Naval Force. Containerised NEMO mortar system can be installed on ships. The problem with these things is that they are expensive with limited range. That is why guns are more common.
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Joined: 4:04 PM - Jan 14, 2013

2:26 PM - Aug 10, 2018 #15

A G Williams wrote:
Hark wrote: That's a nice installation for AMOS.  I've wanted the US Marines to try out this system on an armored vehicle.  Its perfect for what they do.
The USMC has taken a different route: their standard 120mm mortar, the M327, has a rifled barrel and fires spin-stabilised rounds. I can't see them adopting an entirely different 120mm mortar system using different ammo.
No, they won't and its good to have a heavy mortar on hand but I have difficulty understanding why they went with this towed piece rather than twice the firepower on an armored vehicle.  Cost/portability perhaps.
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jua
Joined: 3:54 AM - Mar 17, 2005

5:05 PM - Aug 10, 2018 #16

Portability, primarily. In particular I think it had to be MV-22 compatible. The USMC has always been a relatively light force and AFAIK never has made use of SP artillery except HIMARS, even then it's light truck mounted version of the original.
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Josh

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jua
Joined: 3:54 AM - Mar 17, 2005

5:10 PM - Aug 10, 2018 #17

Actually I just googled it and apparently the USMC has divested the system, with short range apparently being the primary concern.
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Joined: 9:26 AM - Apr 20, 2004

9:13 PM - Aug 10, 2018 #18

jua wrote: Portability, primarily. In particular I think it had to be MV-22 compatible. The USMC has always been a relatively light force and AFAIK never has made use of SP artillery except HIMARS, even then it's light truck mounted version of the original.
Hasn't used SP cannon artillery in a while but did for a long time post WWII. That started with the separate Fleet Marine Force gun batteries and howitzer batteries equipped with the Patton-derived chassis M53 155mm SP gun and M55 8" SP howitzer respectively in the 1950's. Those vehicles both served in Vietnam alongside USMC M109's and eventually M107 175mm/M110 8" replacing the M53/55 (not counting the Ontos SP multi-106mm recoilless rifle and 105mm LVTH sometimes used as artillery). Around the time of the 1990-1 Gulf operation the marines had decided to discontinue use of SP's but some units either still had them or were in the midst of conversion and stopped. I MEF was supported by a battery each of M109A1* and M110A2, II MEF by 3 batteries of M109 and 1 of M110 organized by then as part of general support battalions under the artillery regiments, 11th and 10th Marines respectively. Most of the artillery then was towed M198 155mm howitzer and there were some M101A1 105mm. The experience didn't permanently reverse the decision though and from not long after that, no USMC SP cannon artillery.

*the official history says the ones with 1 MEF were A1, "Order of Battle" by Dinackus refers to all USMC M109's of the time as A3's.

Joe
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Joined: 7:51 AM - Jun 18, 2015

10:27 AM - Aug 11, 2018 #19

NewGolconda wrote: RAN Freemantle class had an 81mm mortar for the first half of their lives. Exactly why, and how often it was exercised is another question
The 81mm on the Freo boat was mostly for illumination.  Not much good for anything else unless you were tied up alongside and the target stayed very still.  Elevation and training were free wheeling and controlled by the aimer to compensate for the movement of the boat.  Never exercised at sea.  Only time i used a mortar was on the Pre Joining Training (PJT) and later when we had to do function tests and both were at the West Head Gunnery Range.  
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Joined: 9:26 AM - Apr 20, 2004

2:44 PM - Aug 11, 2018 #20

NewGolconda wrote: RAN Freemantle class had an 81mm mortar for the first half of their lives. Exactly why, and how often it was exercised is another question
I assume those were US Mk.2 type. These were first installed on larger US Coast Guard cutters in the early 1960's as illuminating guns. But then the type was adopted by the USN, usually in the 'over/under gun' configuration with a .50 M2 HB mg and fitted in the 100's on USN coastal and riverine types in Vietnam, USCG patrol boats also. Some USN mounts were also just the mortar. It's surprising this prolific weapon would only come up indirectly so late in a discussion of modern naval mortars.

It fired the ammunition of standard infantry mortars but was not based on them. It had a recoil system and could be drop or trigger fired. It was only natural from the get go to think of the difficulty of firing such a gun, non-stabilized, accurately for HE fire at significant range from a small vessel in any kind of sea state. But besides illumination and smoke it gained a lot of popularity for awhile as an HE/incendiary gun. The USN torpedo-less PT types of the 1960's (PTF) had their 40mm removed in favor of 'over/under' guns; of course firing unstabilized manual 40mm mounts accurately from vessels that size was also subject to favorable sea state. But eventually the weapon lost currency. Most of the USN types fitted with it themselves disappeared after the Vietnam War. The USCG 82' started out with a 20mm as their main armament, went to .50/81mm plus other .50's in Vietnam era (photo), then to just several .50's in the post Vietnam era.



Joe
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