Naval guns and bearings

[johnshep]

I have two queries that will probably seem very naive.

1. When an account refers to say a starboard side battery of guns and the ship in question has 6 x 6 inch guns, is the battery the full 6 guns or 4 guns as per army usage?

2. I need some help in understanding the bearings given in ship's logs e.g Land Feature A - N 18 W, Land Feature B - N 60 E. If my understanding is correct, the bearings given never seem to exceed 90 degrees. This seems to imply that they are working in quadrants with angles ascending clockwise. Correct, or am I being misled by a very small sample size?

Many thanks for any help

John

[ionia]

1. What Class of ship are you dealing with? How are the 6" guns positioned on board?

2. The two bearings are 342 deg and 60 deg. They are certainly working in "quadrants" but I am not clear on what you mean by "angles ascending clockwise".

[per ardua per mare per terram]

Naval batteries rarely reflected Army usage, because the Navy usually had more guns and larger calibres to play with. In Napoleonic times for example a small squadron of 74s would have more guns than either Napoleon or Wellington at Waterloo. Whilst in WWI one class of 20 - 25 year old cruisers (such as the Edgar class) could muster more ‘heavy’ artillery than the whole British Army in 1914.

Bearings are taken in relation to points of the compass and so were primarily divided into 90 degree segments and then in relation to the principle points. Hence your example Land Feature B - N 60 E. This took over from the notations such as NNE that were less accurate.

[Ron Clifton]

Hello John

Forget about army batteries. Depending on the type of ship, six-inch guns might be the main armament, in which case they would probably be mounted on the centre line, in twin rotating turrets (e.g. HMS Ajax and Achilles of 1939). However, as secondary armament in a larger ship, they would be mounted in single-gun turrets, three on each side (or possibly two on each side and two on the centre line). The "battery" would refer to all the guns on one side.

As regards directions, it would clearly not have been feasible to derive these from the direction of the ship's course as this would often change, so compass bearings would have to be used. I do not know if south-east would be described as N 135 E or S 45 E but one or other of these would presumably be used.

An ex-naval friend of mine who served in the 1950s told me that, for gunnery purposes, changes of direction would be given as right or left, rather than port or starboard, which would be different depending on whether the guns faced forward or aft.

Ron

[per ardua per mare per terram]

Depending on the type of ship, six-inch guns might be the main armament, in which case they would probably be mounted on the centre line, in twin rotating turrets (e.g. HMS Ajax and Achilles of 1939).

In WWI the guns were rarely mounted as twins, the were usually mounted as single guns and often not in enclosed turrets.

[johnshep]

What Class of ship are you dealing with? How are the 6" guns positioned on board?

First of all many thanks for those helpful replies.

The ship I had in mind was the Euryalus in one of her actions off the coast of Gallipoli. She is reported to have opened up her 'starboard 6 inch battery'. Janes illustration of this ship shows a broadside of 2 x 9.2 inch and 6 x 6 inch guns (also 6 x 12-pdrs which are illustrated but not included in the brief note on the broadside armament for some reason). So I assume from this that the 6 inch battery was all 6 starboard guns.

The comments above also raise another interesting point - whether the fire power / destructive power of naval guns can be put on a comparative footing with the fire power of land based artillery guns. Would a comparison of muzzle energy be a valid (if approximate) measure?

John

[per ardua per mare per terram]

On these pictures of His Majesty's Ship Euryalus you can see how the 6 inch guns were arranged in casemates. In naval terms 12-pdrs were pea shooters. They were used to counter torpedo craft, not counted for broadsides against major vessels.

http://www.battleships-cruisers.co.uk/cressy_class.htm

[per ardua per mare per terram]

The comments above also raise another interesting point - whether the fire power / destructive power of naval guns can be put on a comparative footing with the fire power of land based artillery guns. Would a comparison of muzzle energy be a valid (if approximate) measure?

They could not only be put on a comparative footing, they were used in land campaigns. Naval 6-pdrs were fitted into tanks and there were numerous other examples. In the Second Boer War, the army's guns were hopelessly out ranged, so 12-pdrs, 4.7 inch and a 6 inch gun were landed from naval cruisers and used on land mounts. In WWI there were naval/ Royal Marine anti aircraft guns, siege guns up to the 15 inch howitzers.

[David B]

Ron is correct, the main armament is on the centre line and can fire in any direction except the aft guns generally cannot fire forward and conversely the forward

guns cannot fire backwards (that would imply something wouldn't it !). However the secondary armament is normally mounted on either side of the centre of the ship and

can only deal with targets on their side. In my experience when a contact/target/object is tracked, if the bearing is not given in true azimuth the normal reporting

procedure of a target is reported as green or red (starboard or port) followed by the bearing from the ship i.e. green 45 meaning 45 degrees from the ships bow.

David

[ionia]

Ron is correct, the main armament is on the centre line and can fire in any direction except the aft guns generally cannot fire forward and conversely the forward

guns cannot fire backwards (that would imply something wouldn't it !). However the secondary armament is normally mounted on either side of the centre of the ship and

can only deal with targets on their side.

In WW! this was not nescessarily correct. e.g. many 6" gun armed ships had their main armament distributed ahead and astern on the centreline and also in port and starboard batteries.

[ionia]

First of all many thanks for those helpful replies.

The ship I had in mind was the Euryalus in one of her actions off the coast of Gallipoli. She is reported to have opened up her 'starboard 6 inch battery'. Janes illustration of this ship shows a broadside of 2 x 9.2 inch and 6 x 6 inch guns (also 6 x 12-pdrs which are illustrated but not included in the brief note on the broadside armament for some reason). So I assume from this that the 6 inch battery was all 6 starboard guns.

The comments above also raise another interesting point - whether the fire power / destructive power of naval guns can be put on a comparative footing with the fire power of land based artillery guns. Would a comparison of muzzle energy be a valid (if approximate) measure?

John

Bursting charges might make for a better means of comparison. The EURYALIS' 6" guns were BL Mk VII (2570fs) firing a 100lb shell to a maximum range of about 13000 yds at 15 deg elevation. This gun was also used as a heavy artillery weapon on land in WW1 and in coast defence.

[michaeldr]

To supplement PAPMPT's post #7 above

[johnshep]

Once again, very many thanks for those replies. I have learned something new from each and every one of them.

Just to pursue the quarry a bit further; is there any rough and ready way of comparing the fire power of say a land based 60-pdr with a naval 12 inch gun? What I would like to be able to do is come up with some sort of a statement along the lines 'a naval battery of six 6 inch guns had roughly the same destructive power as 2 (3, 4?) land based batteries of 60-pdrs'. Chalk and cheese I dare say, and I imagine there are a lot of variables to be taken into consideration but sometimes ways can be found of measuring the immeasurable, if only by putting things in some sort of batting order.

Thanks again

John

[michaeldr]

Chalk and cheese I dare say, and I imagine there are a lot of variables to be taken into consideration but sometimes ways can be found of measuring the immeasurable, if only by putting things in some sort of batting order.

I'm swimming way out of my depth here, but I wonder if this helps

Shell 60 pound (27.22 kg) shell, later 56 pounds (25.40 kg) with 8 lb Lyddite, later 6 lb Amatol

Shell Lyddite, HE, Shrapnel 100 pounds (45.36 kg)

Calibre 5 inches (127.0 mm)

Calibre 6 inches (152.4 mm)

Rate of fire 2 rounds/min

Rate of fire 8/minute

Muzzle velocity 2,080 feet per second (634 m/s) (Mk I)

2,130 feet per second (649 m/s) (MK II)

Muzzle velocity 2,525 feet per second (770 m/s)

Maximum range 10,300 yards (9,420 m) (original 60 lb 2 c.r.h. shell),

12,300 yards (11,200 m) (modified 8 c.r.h. shell shape) (Mk. I)

15,000 yards (14,200 m) (56 lb Mk 1D 10 c.r.h. shell, Mk. II gun)

Maximum range On Field carriage Mk. II : 13,700 yards (12,530 m)

Naval : 14,600 yards (13,350 m) (light charge); 15,800 yards (14,450 m) (heavy charge)

Black = 60-pdr & Red = Naval 6-inch

See http://en.wikipedia.org/wiki/BL_6_inch_Mk_VII_naval_gun

& see http://en.wikipedia.org/wiki/BL_60_pounder_gun

[MikB]

So a naval 6" battery (with casemated guns on a Cressy-type cruiser effectively a broadside) could therefore put out 48 rounds a minute, totalling about 4800 pounds of shell.

A battery of 4 60-prs would put out 8 rounds a minute (can 2 rounds a minute be right? Seems low) or 480 pounds of shell.

So on weight of metal the cruiser roughly matches 10 4-gun batteries.

But 10 army batteries would distribute its 4800 pounds to 80 rounds, so might be able to achieve a better coverage in lethal density of flying splinters or shrapnel than the 48 naval rounds.

On the other hand, the naval rounds could penetrate concrete emplacements that would shrug off 60-prs.

And on the other, other hand, casemated secondary armoured-cruiser batteries were notorious for being unusable in much of a seaway, being low in the ships, whereas land-based artillery - especially against well-surveyed and registered targets - was less affected by weather.

So yes, chalk and cheese it is.

Regards,

MikB

[per ardua per mare per terram]

Ron is correct, the main armament is on the centre line and can fire in any direction except the aft guns generally cannot fire forward and conversely the forward guns cannot fire backwards (that would imply something wouldn't it !). However the secondary armament is normally mounted on either side of the centre of the ship and can only deal with targets on their side. In my experience when a contact/target/object is tracked, if the bearing is not given in true azimuth the normal reporting procedure of a target is reported as green or red (starboard or port) followed by the bearing from the ship i.e. green 45 meaning 45 degrees from the ships bow.

David

In WWI, the focus of this forum, even battleships did not all have their main main armament on the centre line.

It looks like the ways of expressing bearings had altered between WWI and your day.

[MikB]

Take a gander at this 'ere site:-

http://www.dreadnoughtproject.org/tech/

Wander about and run some of the tutorials - eg. the one on the Dumaresq. It's allegedly based on RN WW1 techniques, and both compass bearings and relative bearings are used in discussion, though only compass bearings in working up the firing solution on the Dumaresq.

The lookouts might well describe targets by relative bearings, because their kit would be on fixed pillars calibrated to ship's head. But by the time it reached the guns, it would have been through several sets of computations.

Regards,

MikB

[michaeldr]

Re MikB's post #15, and bearing in mind that we are talking about shore bombardment off Gallipoli (Suvla, August 1915) then this would seem to apply

"But 10 army batteries would distribute its 4800 pounds to 80 rounds, so might be able to achieve a better coverage in lethal density of flying splinters or shrapnel than the 48 naval rounds."

while concrete emplacements would not come into it (nor would the sea conditions be important)

Edited 25 June , 2010 by michaeldr

[ionia]

So a naval 6" battery (with casemated guns on a Cressy-type cruiser effectively a broadside) could therefore put out 48 rounds a minute, totalling about 4800 pounds of shell.

Four rounds per minuite would be the sustainable rate of fire of the 6" BL Mk VII, reducing the output to 2400lbs p.m.

[MikB]

Four rounds per minuite would be the sustainable rate of fire of the 6" BL Mk VII, reducing the output to 2400lbs p.m.

That doesn't much surprise me - and I wonder if the 60-pr might've been capable of more than 2. So we're working at an equivalence of maybe 5 4-gun batteries.

I don't know if there were concreted enemy emplacements at Suvla, but there certainly were at other places in the Gallipoli campaign.

There are also questions of elevation - usually limited to 20 degrees or so at that time - fire control against targets high above sea-level, and ammunition supply. I wouldn't expect ammunition outfits for cruisers were sufficient for the very long-drawn-out bombardments common in land actions, and resupply would presumably have required port facilities within a short steaming time of the scene of action.

Regards,

MikB

[michaeldr]

MikB,

Suvla in August 1915 is a presumption on my part, as Thales also has a current question regarding artillery at Lala Baba. He will no doubt correct me in due course.

If correct then this was, for the most part, open country with little in the way of Ottoman prepared positions, so I think concrete does not have to enter the equation.

The terrain did not reach any great height at Suvla and I do not recall reading of it presenting any problems to the naval gunners

Supplies were held at the near-by island of Lemnos (the harbour was Mudros) and the army suffered the same shortages as the navy, so again I do not think that this has to enter the equation

regards

Michael

[joseph]

Hi,

"There are also questions of elevation - usually limited to 20 degrees or so at that time - fire control against targets high above sea-level, and ammunition supply. I wouldn't expect ammunition outfits for cruisers were sufficient for the very long-drawn-out bombardments common in land actions, and resupply would presumably have required port facilities within a short steaming time of the scene of action."

The RN had this covered resupply would be as for the army at mudros and lemnos.

Regards Charles

[michaeldr]

Apologies to Thales for drifting off topic here

But many thanks to Charles for that picture – Can you date it?

I had a thread awhile back on the battleships with howitzers – see

 

regards

Michael

[joseph]

Michael,

The photo would be taken first half of 1915 as the same ship is sporting a cow catcher. This is a standard howitzer not of the bomb throwing type 7.5 inch and 11 inch.

Regards Charles

[michaeldr]

Thanks again for your help here Charles

I have copied your photograph across to the old thread

where it helps to answer one of the original questions there

regards

Michael