How good were Dunkerque Class?

[vinnye]

Given that this class of ship was conceived, designed and built to counter the KM Panzerschffe - Graf Spee etc, how effective would they have been? I read a Wiki article that said Dunkerque suffered bow damage in the North Atlanic, so she may have had some issues?

 

[davebender]

By 1932 the world was awash with so called "Treat Cruisers" displacing 10 to 12,000 tons and armed with 8" main guns. I think the Dunkerque class were ideal for catching and destroying those cruisers. So were German Scharnhorst class.


Historically the Dunkerque class never got a chance to prove themselves. Give the two French ships to ABDA and the Battle of Java Sea looks a lot more favorable for the Allies. Attach the two French BC (or similiar design USN ships) to American cruiser force at Guadalcanal and Japan has a much tougher nut to crack.

 

[vinnye]

I agree. What made me question how good they would have been was the reference to bow damage in the North Atlantic?
If they were to try to hunt down Graf Spee - would they have had better sea keeping than them?
Or if they were to engage Scharnhorst - would they have got the best of such an engagement?
I know that their design was supposed to makw them 11 inch shell proof - but that does not mean in real engagements it would be the case.

 

[fastmongrel]

Handsome looking vessels but they do seem to have been too lightly built damaging themselves when firing the main armament. They also had accuracy problems and never fired as fast as planned.

 

[vinnye]

Yes a fine looking ship for sure. I also like the Richelieu class Battleship design. The French seem to have had a flair for making elegant ships.
For ships with all of their heavy armament up front - they look good. I am afraid the same can not be said for Rodney and Nelson. But I think theses two would have the edge in an engagement.

 

[davebender]

Dreadnoughts and cruisers are complicated pieces of machinery. Dunkerque class were not unique in having teething problems. If their service life had not been cut short in 1940 chances are Dunkerque problems would have been fixed.

 

[vinnye]

Yes, modifications would no doubt have been made from experience gained during srvice.
They had better avoid a real Battlecruiser or Battleship with 14 inch or above.
From Wiki :
Dunkerque, after painfully breaking her mooring ropes, quickly suffered four-15 inch shell hits. The first shell rebounded off the upper 330 mm turret roof, killing all the men in the right half-turret (the left half-turret remained operational). The second shell damaged the aircraft installations, and the last ones – piercing the armored belt – damaged boilers and destroyed the electric power plant.

 

[Juha]

Yes, modifications would no doubt have been made from experience gained during srvice.
They had better avoid a real Battlecruiser or Battleship with 14 inch or above.
From Wiki :
Dunkerque, after painfully breaking her mooring ropes, quickly suffered four-15 inch shell hits. The first shell rebounded off the upper 330 mm turret roof, killing all the men in the right half-turret (the left half-turret remained operational). The second shell damaged the aircraft installations, and the last ones – piercing the armored belt – damaged boilers and destroyed the electric power plant.

All BCs should avoid ships armed with 15" guns, look what happened to HMS Hood. Even smaller BBs like Scharnhorst and Gneisenau should avoid proper BBs.

Juha

 

[vinnye]

True Juha, that's why most of them were designed to be faster than most BB, but not all.
Hood, Bismark and R class to name a few.
I think an interesting match up would be Scharnhorst v Dunkerque.
My vote would be Dunkerque. I think she has the edge in armour, firepower but lacks a shake down period so would need to sort out technical issues.

 

[fastmongrel]

I think an interesting match up would be Scharnhorst v Dunkerque.
My vote would be Dunkerque. I think she has the edge in armour, firepower but lacks a shake down period so would need to sort out technical issues.

Dunkerque had been at sea since Jan 1938 so she should have had a good shake down by the time she could theoretically meet Scharnhorst in November 1939 when Scharnhorst was operational. It would be a fascinating battle but personally I would give Scharnhorst the slight edge with her thicker belt armour and more accurate but lighter, faster firing guns.

 

[vinnye]

I know DoY had slightly bigger guns than Dunkerque, but the 14 's did some serious damage. From Wiki ;
At 16:50, Duke of York opened fire at a range of 11,000 m (12,000 yd); Scharnhorst quickly returned the fire. Five minutes after opening fire, one of Duke of York's 14 in (35.6 cm) shells struck Scharnhorst abreast of her forward gun turret. The shell hit jammed the turret's training gears, putting it out of action. Shell splinters started a fire in the ammunition magazine, which forced the Germans to flood both forward magazines to prevent an explosion. Turret Bruno's magazine was quickly drained, though the ship was now fighting with only two-thirds of her main battery.[56] Shortly thereafter, another 14 in shell struck the ventilation trunk attached to Bruno, which caused the turret to be flooded with noxious propellant gases every time the breeches were opened. A third shell hit the deck next to turret Caesar and caused some flooding; shell splinters caused significant casualties. At 17:30, shells struck the forward 15 cm gun turrets and destroyed them both.[57]

At around 18:00, another 14 in shell struck the ship on the starboard side, passed through the thin upper belt armor, and exploded in the number 1 boiler room. It caused significant damage to the ship's propulsion system and slowed the ship to 8 kn (15 km/h; 9.2 mph), though temporary repairs allowed Scharnhorst to return to 22 kn (41 km/h; 25 mph). She managed to add 5,000 m (5,500 yd) to the distance between her and Duke of York, while straddling the ship with several salvos. Shell splinters rained on Duke of York and disabled the fire-control radar.

But, I doubt if Dunkerque would have fared any better?
Maybe against 11 inch, she may have ?

 

[vinnye]

Also found this in Wiki -
The Germans response to Dunkerque were the Scharnhorst-class battleships, both laid down in 1935. They were larger, had better armour, but nine guns of only 280 mm caliber. These guns were improved versions of the type used by the Deutschland-class with longer barrels and higher muzzle velocity. A heavier armament had been pre-empted by negotiations for the 1935 Anglo-German Naval Agreement.[16] As the Dunkerques were designed to withstand 280mm shells, the French saw no need for a new class in reply.

This would suggest that the French at least, considered Dunkerque to be the equal or superior to Scharnhorst.

 

[davebender]

In a perfect world I agree. However you don't always get a choice.

Dunkerque class were eggshells armed with hammers, similiar in concept to WWI era Invincible class battlecruisers. The concept had some problems during WWI and sooner or later they would have encountered similiar problems during WWII.

I think Germany did the smart thing by paying a bit more for battleship scale armor on their battlecruisers during both world wars.

 

[Juha]

In a perfect world I agree. However you don't always get a choice.

Dunkerque class were eggshells armed with hammers, similiar in concept to WWI era Invincible class battlecruisers. The concept had some problems during WWI and sooner or later they would have encountered similiar problems during WWII.

I think Germany did the smart thing by paying a bit more for battleship scale armor on their battlecruisers during both world wars.

I agree most but I'd not call even Dunkerque, even less the better armoured Strasbourg, eggshell.

Juha

 

[davebender]

Kongo. Laid down 1912.
203mm armor belt.
8 x 356mm/45 main guns.
27.8 knots. (30 knots after 1930s refit). 8,000 miles @ 14 knots.

Dunkerque. Laid down 1932.
225mm armor belt.
8 x 330mm/50 main guns.
31 knots. 7,850 miles @ 15 knots.

 

[vinnye]

I think the biggest difference between Dunkerque and Kongo and others is the all up front armament.
This can be an advantage if you are hunting your opponent down, but a major flaw if you have to disengage and withdraw.

 

[delcyros]

Advantages DUNKERQUE:

[+] powerful main battery. The 13"/50 are similar in penetration power to KGV´s 14"/45
[+] good optical FCS with excellent prediction
[+] good armour protection of the embedded vitals vs 11", particularely at long range

disadvantages DUNKERQUE:
[+] poor dispersion patterns
[+] less redundancy
[+] poor practical rate of fire

advantages SCHARNHORST:
[+] high practical rate of fire, elevated optics, including radar ranging FCS
[+] good armour protection of the embedded vitals vs 13", particularely at short range
[+] tight dispersion patterns
[+] high degree of redundancy

disadvantages SCHARNHORST:
[+] large target area

The relatively fine hullshape of both vessels allowed relatively high speed at calm weather but caused wave issues at medium and poor seastate.
Thus, both ships are wet in North Atlantic Weather. DUNKERQUE is probably worse, as it lost both (!) fwd turrets in medium weather in 1939 during a maneuvre in medium seatate due to water ingress. Fast in calm weather but exceptionally poor in adverse conditions.

Otherwise the dsigns are matched equally, S&G hold a marked advantage at short range due to their protective scheme, higher rate of fire and tighter dispersion while DUNKERQUE holds an advantage at long range (deck armour), where cyclic rate of fire is low for both designs and additional spread may help if MPI is not perfectly well known...

 

[davebender]

That would leave Dunkerque with no operational main guns.

I've got to assume French Navy jumped on that problem and implemented some sort of fix.

 

[vinnye]

So if I am reading your synopsis correctly Delcyros, Dunkerque should have the advantage if she can keep the range opened?
I see that Scharnhorst had good armour at short range so she would want to get in close and scrap it out?

That is of course if Dunkerque can keep her guns working!

 

[delcyros]

"Long range" as I mentioned it previously is probably not sufficient. Extreme range (>25,000 yard) would be more correct. This is possible at good weather and air spot, particularely at the calm Mediterranean Seas, the intended operational environment of these vessels (to counter the italian threat).

Part of the problem is the exceptionally clean aerodynamic design of the high velocity shell. The angle of fall exceeds 20 deg (that´s where functional penetration starts to become effective) only at >26,000 yard.
At closer ranges, where the angle of fall is less than 20 deg (= 70 deg impact obliquity against a horizontal, flat deck armour plate), ricochetting off becomes increasingly likely instead, and -where penetration happens at less than 70 deg, the fuse will not be triggered (rendered blind). Only very few fuses of ww2 had graze function that allowed some functionability (30 to 70%) in the obliquity range 70 to 80 deg. Above 80 deg obliquity, a projectile ricochets off from surfaces like water.

for the 13"/50:
10 deg angle of fall =17,500 yard -ricochet
20 deg angle of fall = 26,000 yard -begin of functional deck penetration
30 deg angle of fall = 34,000 yard
-penetrates 110mm deck armour at 30,100 yard

for the 11"/54:
10 deg angle of fall = 16,300 yard -ricochet
20 deg angle of fall = 23,700 yard - begin of functional deck penetration
30 deg angle of fall = 30,000 yard
-penetrates 105mm deck armour at 28,100 yard

[+] advantage of the 13"/50 APC is the very large burster charge (44.7 lbs TNT compared to 14.55 lbs TNT in the L4.4 28.3cm APC).
The french projectile has a significantly higher percent weight devoted for the burster.
The flip side of the coin is that armour penetration should be compromised at obliquity impact.