[dhanushmenon]

Splendid thread! Having churned out stand out classics about the Indian Navy, Naval Aviation, Ship building, Foxbats and what not, I knew that it's only a matter of time before another classic on the Coast Guard rolls out from your stable. Absolutely involving and incredibly informative (as always). Cheers to your relentless efforts sir.

Just to add a point of information:-
Coast Guard Aviation added another feather to its cap last month when night deck landings were undertaken onboard ICGS Shoor. This greatly enhances the spectrum of operations and flexibility.
ICGS Shoor became the first Coast Guard ship to undertake night deck operations. Landing trials were undertaken off Goa by CG ALH Dhruv, flown by pilots of Indian Navy.

[V.Narayan]

Originally Posted by Sutripta

In use and in design how do the different big guns (field, tank, naval) differ? Asking because Rommel used AA guns as field/ anti tank guns to devastating effect.

I am no expert but let me try to share what little I know as an amateur. There will be others on Team BHP better qualified by profession to answer this.

Naval Guns versus Land based Artillery: BLUF — Bottom line up front - The naval gun of similar calibre can fire greater distances because it can have a longer barrel, be of heavier construction, shoot with heavier projectiles using larger propellants capable of a slower burn rate.

A gun is all about projectile weight, projectile velocity, propellant charge, barrel length & strength and calibre. Land based artillery - field gun or tank mounted - while very powerful & lethal in their own right are often for the same calibre lighter than a naval gun. The naval gun because it is mounted on a ship weighing xxxx hundreds or thousands of tonnes and has the benefit of automatic loading is usually of a much heavier mounting, heavier barrels and almost always with bigger propellant charges than comparable modern land guns.* This usually gives it a greater range and sometimes bigger heaver more lethal projectiles. A modern naval gun would be of between 51 to 64 calibers ie the barrel length to diameter while a typical field gun would be 39 calibres. The greater the calibers the more the propellant charge's kinetic energy can be transferred to the projectile - hence the velocity and range.

An army gun is often manually loaded and for good reasons of flexibility, reliability and ease of movement. Therefore weight of projectile & propellant are smaller. Automatic loading in naval guns means the designer is not restricted to the weight a man can lift and ram (into the chamber). All this is relative. You don't want to be at the receiving end of a Bofors 155mm or a T-72's 125mm.

A tank mounted gun focuses on shells to fly straight and level at very high velocities in order to destroy other tanks or structures. The focus is more on speed of shell than weight - hence specialized armour penetrating shells like APDS (armour piercing discarding sabots). Tank guns are not range focused due to their role and their inability to elevate (elevation of 68 degrees is ideal for range optimization) #

As you move to smaller calibre guns - 40mm and below the differences diminish except in mounting arrangements, number of barrels depending on role.

In WW2 the biggest & best mobile German gun was the 88mm anti-aircraft gun. In an age before missiles such a size was needed to get a shell up to 20,000 feet where the bombers flew and to carry explosive warhead large enough to cripple a bomber even with a near miss (proximity fuse). The kinetic energy of this gun, projectile weight x velocity x velocity was so good that Rommel discovered he could use them in the horizontal plane to knock off enemy tanks. Very quickly shells suited to the task were deployed - 'armour piercing high explosive' -APHE - as opposed to the anti-aircraft ones which were high explosive proximity fused, HE-PF.

* For example a typical 155mm Army field gun would weigh around 11 tonnes. A 127mm Naval ship mounted gun would weigh around 22 to 25 tonnes without counting the structural engineering elements that hold it in place.
# the shell of a Naval gun or a Army field gun would have an initial velocity of say 750 to 900 metres/second. An anti-tank discarding sabot round fired by a tank gun would have a velocity broadly in the 1100 metres/second range.

Originally Posted by dhanushmenon

Splendid thread! Having churned out stand out classics about the Indian Navy, Naval Aviation, Ship building, Foxbats and what not, I knew that it's only a matter of time before another classic on the Coast Guard rolls out from your stable. Absolutely involving and incredibly informative (as always). Cheers to your relentless efforts sir.

Thank you very much for your words of appreciation. Coming from you this has a special meaning :-)

Just to add a point of information:-
Coast Guard Aviation added another feather to its cap last month when night deck landings were undertaken onboard ICGS Shoor. This greatly enhances the spectrum of operations and flexibility.
ICGS Shoor became the first Coast Guard ship to undertake night deck operations. Landing trials were undertaken off Goa by CG ALH Dhruv, flown by pilots of Indian Navy.

Thank you for sharing this with all our readers. For some one not in aviation it is hard to fathom the complexity and sheer risk of a night landing on a small deck that is always rolling and pitching and moving away from you! There is simply no room for error.

[Sutripta]

^^^
Number of questions, but esp. two
A) I thought that in large (ie on capital/ battleships) naval guns the propellent was loaded separately from the projectile. (Much like muskets of yore). And there was a fair bit of manual work involved.
B) AA and proximity fusing - wasn't there also a time delay fuse?
C) When did rifling fall out of favour, and why. (Fin/ spin stabilised).

Regards
Sutripta

[V.Narayan]

Originally Posted by Sutripta

Number of questions, but esp. two
A) I thought that in large (ie on capital/ battleships) naval guns the propellant was loaded separately from the projectile. (Much like muskets of yore). And there was a fair bit of manual work involved.
B) AA and proximity fusing - wasn't there also a time delay fuse?
C) When did rifling fall out of favour, and why. (Fin/ spin stabilized).

(A) Up to the ships designed in WW2 the loading of the projectile and propellant was done manually often with the help of hoists/some mechanical leverage. Propellant & shell, today maybe one unit or separate - varies with gun and size. Smaller units up to 57mm / 76mm it would almost always be a single unit. Bigger than that it is often separate. All large Naval guns today have fully automatic loaders with a below deck magazine.

(B) Time delayed fuses are more for surface targets like armoured vehicles or ships - both for shells and missiles. Anti-aircraft shells are almost entirely proximity fuzed - same for anti-aircraft missiles.

(C) Smooth bore guns, made popular by the Soviets, in the late 1970s with their classic 125mm 2A46 gun fitted on the T-72 tank and every Russian tank since. Smooth bores, of any nation, are usually found only in the guns of main battle tanks. The Russians , Germans and French prefer smooth bore, for their tanks, as it imparts a higher velocity to the shell which is much needed for anti-armour duties. British & American stayed with rifled tank guns but the Americans shifted over about 20 odd years ago. Only the British have stayed with rifled main battle tank guns. All other guns/cannons remain rifled - naval, artillery, aircraft mounted et al.

As mentioned in the last post this is not my area of expertise. Others on the forum could add greater insights.

[DrPriyankT]

Originally Posted by V.Narayan

(A) Up to the ships designed in WW2 the loading of the projectile and propellant was done manually often with the help of hoists/some mechanical leverage. Propellant & shell, today maybe one unit or separate - varies with gun and size. Smaller units up to 57mm / 76mm it would almost always be a single unit. Bigger than that it is often separate. All large Naval guns today have fully automatic loaders with a below deck magazine.

(B) Time delayed fuses are more for surface targets like armoured vehicles or ships - both for shells and missiles. Anti-aircraft shells are almost entirely proximity fuzed - same for anti-aircraft missiles.

(C) Smooth bore guns, made popular by the Soviets, in the late 1970s with their classic 125mm 2A46 gun fitted on the T-72 tank and every Russian tank since. Smooth bores, of any nation, are usually found only in the guns of main battle tanks. The Russians , Germans and French prefer smooth bore, for their tanks, as it imparts a higher velocity to the shell which is much needed for anti-armour duties. British & American stayed with rifled tank guns but the Americans shifted over about 20 odd years ago. Only the British have stayed with rifled main battle tank guns. All other guns/cannons remain rifled - naval, artillery, aircraft mounted et al.

As mentioned in the last post this is not my area of expertise. Others on the forum could add greater insights.

Adding a bit of information here. Our homegrown Arjun Tank too has a rifled main gun. AFAIK rifled guns provide greater accuracy, as the spinning shell stays truer to its course , as compared to a shell fired from a smooth bore gun. That’s the reason why infantry guns of all calibers like 5.56mm, 7.62mm and 9mm are rifled. It’s due to the fact that infantry men value accuracy over range for close combat.

[Sutripta]

Originally Posted by V.Narayan

(B) Time delayed fuses are more for surface targets like armoured vehicles or ships - both for shells and missiles. Anti-aircraft shells are almost entirely proximity fuzed - same for anti-aircraft missiles.

The proximity fuse was a British (further developed by Americans) invention. So what fuze did shells of the Flak 88 use?

Regards
Sutripta

[Sutripta]

Originally Posted by DrPriyankT

That’s the reason why infantry guns of all calibers like 5.56mm, 7.62mm and 9mm are rifled. It’s due to the fact that infantry men value accuracy over range for close combat.

Now if someone would start a thread on small arms.

Regards
Sutripta

[mbsomanna]

Very informative thread Sir.
Most of CG ships in the world have colorful paint scheme, unlike the typical colors used by the armed forces.

In 2014, I had the opportunity to get up close with one of our hovercraft's parked on Malpe beach near Mangalore. I had a chat with the Officer on board as well.

[Thad E Ginathom]

Originally Posted by mbsomanna

Most of CG ships in the world have colorful paint scheme, unlike the typical colors used by the armed forces.

The intention of one is to be camouflaged; the intention of the other, I suppose, is to be seen

one of our hovercraft's

Like sheep or deer, the plural of craft is craft: one hovercraft, two hovercraft...

When I have seen these craft/vehicles, on land or sea, I have been amazed by the amount of noise they make!

[Sutripta]

^^^
Hope it is not causing you to tear your hairs out.

Regards
Sutripta

[V.Narayan]

Originally Posted by Sutripta

The proximity fuse was a British (further developed by Americans) invention. So what fuze did shells of the Flak 88 use?

As you correctly point out the proximity fuse was invented by the British. In WW2 the Germans did not have it. The 88mm Flak gun shells used timed fuses which (knowing the velocity of the shell & its de-acceleration) were designed to explode the shell at a pre-set altitudes usually between 16,000 to 20,000 feet in a cube fashion. The German radars would determine the altitude of the incoming bombers and the timed fuses set accordingly. Not as effective as a PF but it worked.

Fuzes are difficult to design and the hardware has to withstand an acceleration of over 10,000 G force (!!) when the gun fires and then function as designed a few seconds later after having lain dormant for 3 years prior in an ammunition store.

[V.Narayan]

Coast Guard commissions ICGS Sujeet Offshore Patrol Vessel

https://www.newindianexpress.com/nat...a-2236611.html

ICGS Sujeet is the 8th vessel of the planned 11 ship strong Samarth class being built for the Indian Coast Guard. These are long range Off Shore Patrol vessels for open ocean all-weather operations. To be truly open ocean capable with operating a helicopter the vessels needs to be 2000+ tonnes in displacement. The Coast Guard is simultaneously also building a similar OPV series, almost sister ships of the 7 strong Vikram class 5 of which have been commissioned.

Off Shore Patrol vessels focus on protecting the EEZ, anti-piracy patrols, anti-drug running, anti-terrorism and protecting off shore oil assets. For this they are equipped with a medium helicopter, a 30mm rapid fire gun, light & heavy machine guns and fire fighting at sea gear. All ICG OPVs are equipped for some degree of oil pollution and sludge clearance.

Specifications:

Displacement: 2450 tonnes

Length: 105 metres

Powerplant: 2 MTU medium speed diesels rated at 12,200 shp continuous married to 2 controllable pitch propellers

Speed: 23 knots, sustained

Range: 6000 nautical miles at 12 knots {this seems to be understated according to me}

Armament Fit: 1 x 30mm CRN gun; 1 x Dhruv medium twin-engined helicopter; 2 x 12.7mm HMG

The Indian Coast Guard now operates 22 large OPVs, 45 Fast Patrol Boats in the ~200 to 300 tonne range and a further 73 fast patrol craft in the 90 to 110 tonne range {for coastal & inshore work}. It is now the third largest Coast Guard after the US and Japan.

Source: Coast Guard Twitter
ICGS Sujeet, built by Goa Shipyard

Source: Goa Shipyard
ICGS Samarth, lead ship of the class

[Jeroen]

Originally Posted by V.Narayan

[h3]
Displacement: 2450 tonnes

Length: 105 metres

Powerplant: 2 MTU medium speed diesels rated at 12,200 shp continuous married to 2 controllable pitch propellers

Speed: 23 knots, sustained

Range: 6000 nautical miles at 12 knots {this seems to be understated according to me}

Smart looking ship!

Of course, when it comes to range it is all down to speed, but yes this seems a bit on the low side for a 105 meters long, only 2450 tonnes ship at 12 knots

As this is a full displacement type of craft it means that its range at top speed will drop to less than half, well under 3000 nm. (speed correlates to power 3 to engine power)

I get you need a certain size of ship to operate helicopters off in an ocean. Even so do coastal vessels really need that much range? Or rather, does the Indian coast guard operate that far out from coastal waters, for long periods of time?

Jeroen

[dragracer567]

An interesting article in the Economist about the Chinese Navy. Turns along with their Navy, their CG has also been growing at a (almost comically) rapid pace. The Chinese CG has about 500 vessels, 87 of which are more than 1,500 tonnes (51 in 2015, just to show how fast they grew). Their ships also have impressive tonnage with the Zhaotou-class cutter weighing 12,000 tonnes (the world's largest CG ship) while the 4000 tonne type 818 patrol ship basically being modified 054A frigates (the largest and most potent Pakistani Navy warship).

Similar to what Jeroen explained in The Netherlands, the Chinese combined multiple maritime security agencies in 2013 to form the Chinese Coast Guard while in 2018, it was put under the command of the People’s Armed Police, a paramilitary force that reports to the Central Military Commission, the country’s supreme military body. In effect, this turned China’s coastguard into a branch of the armed forces - like its counterparts in the US and India (nice to see India being more forward-thinking than the Chinese here).

Here is the article link

[V.Narayan]

Originally Posted by Jeroen

Smart looking ship!

Of course, when it comes to range it is all down to speed, but yes this seems a bit on the low side for a 105 meters long, only 2450 tonnes ship at 12 knots

As this is a full displacement type of craft it means that its range at top speed will drop to less than half, well under 3000 nm. (speed correlates to power 3 to engine power)

I get you need a certain size of ship to operate helicopters off in an ocean. Even so do coastal vessels really need that much range? Or rather, does the Indian coast guard operate that far out from coastal waters, for long periods of time?

Jeroen

In the 1950s to 1980s the Indian Navy used to operate three British built Leopard class frigates of identical tonnage and diesel powered. Mind you these were early 1950s designed diesels. Those ships {my father served on one of them} did 7500 nautical miles at 16 knots {I do not know about reserves}. Even if we ignore improvements in diesel technology these Coast Guard OPVs at least should do something similar. Indian Coast Guard vessels typically operate 150 to 300 nm off shore for two to three week long patrol. That would be roughly 7500 nm at 14 knots. Our biggest role is around anti-terrorism, anti-piracy, protection of off shore oil rigs and prevention of infiltration by our Pakistani friends. Fisheries come after all this.