The range on "grapeshot" is not very long at all. It is good for anti-personnel use, or close range ant-air use in tanks. A .50 caliber machine gun has more effective range than grapeshot out of a 5" gun. The 20mm gatling gun ciws is way better than giant shotgun shells out of a deck gun.

I don't believe that to be the case, you could easily get a weapons Manufacturer to get a VT Fuse on it and get it go off 300m before required Range. Plus the Heavier the rounds used the better, TUNSTEN Balls or Flechette rounds. Plus there is no reason why a Large calibre Gun system could not be used as a Second line Tactical Shotgun, The CIWS remains your Primary (Or maybe the ability to 30kts in the opposite direction!) but CIWS are difficult to maintain and if i am honest somewhat fickle. A Large scale Naval Shotgun firing a shell every second to 0.75s would be terrifiying. I think it would have numerous uses, it could be used to put a wall of tungsten up against an incoming ASM. Plus no Naval Officer worth his salt would turn down another item putting more rounds in the sky against an "EXOCET" et al.

Remember Naval Engagements of this nature would be a close in Knife fighting scenario especially against WBSIED (water bourne Suicide IED'S) the aim is surround and pummel a superior opponent with numerous targets. All ROE requires a positive VISUAL IDENTIFICATION unless a relaxation is inforce therefore A CAPTAIN will wait until he has hostile intent/Pos VID before bringing the Rain. Naval Engagements against FIAC type craft do not happen at range. It is not UDALOY, or MEKO 360, its a boat usually under 12metres doing a hell of rate of knots, engagement will be Sub 3nm....

[edit on 1/6/09 by LT mikey]

An interesting notion. The Japanese tried something similar in their largest calibre naval guns (16" and 18.1") during WWII for anti aircraft use. It was, by all accounts, less than successful, and damaged the guns that fired it. Can't remember the name right off the top of my head...

The damage was to the rifling of the guns, and if I"m remembering correctly, the recoil mechanisms.

The guns that fire a grapeshot round would have to be smoothbore, and perhaps specially made. A close in system, for those mobbing attacks you mentioned. I don't see a real reason to use them as a stand off weapon. But than I'm nothing even resembling an expert in these matters, though I play one on the internet...

Interesting thought, though...

Hmm... I have been thinking about that, if you went for an ALL UP ROUND that fired the Shell with a VT fuse (Variable Timed Fuse) it would be no different to any other Shell. It could go off 10-30m from end of barrel that way no damage to the barrel would occur.

Obviously TANKs with 120mm Smoothbore guns are used to it.

SABOT rounds with a sack of balls rather than a Dart Anyone?

Sorry guys the term GRAPESHOT was misleading, what i am really advocating is a CANISTER type Shell capable of being fired through rifled or a modded round for smoothbore. Which once fired and clear of barrel seperates to form a Shot Gun Shell type effect in flight and upon landing.

I have terrible visions of you all thinking i was firing ball bearings down my Barrels and pitting and destroying them, as a Gunner i would weep...

[edit on 1/6/09 by LT mikey]

Canister shot won't work well from a rifled gun either. The canister will have an imparted spin from the rifling. When the canister breaks open, the shot will retain the angular momentum, and proceed to spread far faster than the pattern from a conventional shotgun shell. The result will be a very wide pattern, but a very thinly-populated one, in terms of shots per square foot of beaten zone.

As someone pointed out above, you'd be better off to simply strafe a .50 cal or 20mm (or better yet, a 30mm Bushmaster II) over the same area. The result would be more lethal to the target, cheaper (no need to develop, test, and manufacture a new type of round), and easier on the logistical side of things (New types of main gun ammo = fewer rounds of each type in an already crowded magazine, more items to track through inventory, and more updates to the fire-control software). If the hostile targets are too large to be threatened by machine gun / light cannon fire, the odds are good that they'd require the use of HE rounds from the main guns in any case.

As you point out ROE restrictions, and the expected short ranged engagement zone, more light and medium (up to ~30mm) mounts would seem to be more effective. You can always use the big tubes to deal with the longer ranged badguys, but a number of lighter mounts would, I believe, be more effective to counter a 'swarm' attack. Further, there would be less risk of fratricide with lighter rounds, although they would do a proper job on the light boats the badguys would likely employ.

Well i believe "grape shot" was first used in the civil war if I'm not mistaken and was issued to both naval and field artillery by the end of the war it was replaced by canister shot which was quite effective against antipersonnel. The only practicality I see is using it against air attacks but its not like back in ww2 where you had to get close to the ship to bomb it. I mean technology is advanced and as far as naval warfare goes more emphasis is placed on long range because face it most countries nowadays have weapons that can really reach out and touch you. But maybe it could be effective against small ships or whatnot. Hell maybe it'd be a good defensive weapon against pirates you know. Instead of calling in a navy sniper team just get one of them deck shotguns and let it fly. I know if a giant shotgun was aimed at me I'd get the !*#@ outta there!

No, Grape (at least the concept, if not called 'grapeshot') was used very early in cannon development. Canister was used in the US war with Mexico. It may have been used earlier, but I wasn't a redleg, so that isn't my area. Any graduate of the Cherokee County Community College for Cannon-cockers could probably give chapter and verse.

Obviously such rounds violate the Geneva Protocol if you're going to use them around civilians - as do any other indiscriminate weapons.

That would apply if the only thing in the area were small boats manned by combatants as suggested.
Of course, on previous record someone might blast a boatload of Iranian schoolchildren by accident.