View source for Acasta Class Destroyer (1912)

Twenty [[Destroyer|destroyers]] of the '''Acasta Class''' (redesignated the '''"K" class''' in 1913{{Conways1906|p. 75}}) were completed as part of the 1911-1912 Programme.  Twelve were Admiralty design, and eight were Specials.

They were the first Royal Navy destroyers to drop the 12-pdr gun and use only 4-in guns, increasing to three such weapons from two although the third only had 35 degrees of firing arc on each beam.{{March|p. 127}}

At the outset of the war, these ships comprised the {{UK-DF|4}} under leader {{UK-Swift}}.{{DittColl|p. 15}}

<div name=fredbot:ships>
{| class="wikitable collapsible collapsed" border=2 cellpadding=2 cellspacing=0 style="margin: 0 0 1em 0.5em; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse;" align=center;
|-
! colspan=6 align=left|Overview of 20 vessels
|-
| colspan=6 align=left|<small>Citations for this data available on individual ship pages</small>
|-
! align=center | Name 
! align=center | Builder 
! align=center | Laid Down 
! align=center | Launched 
! align=center | Completed 
! align=center | Fate
|- align=left
| {{Template:UK-1Acasta}}
|[[John Brown & Company]]
|
|10 Sep, 1912
|
| May, 1921
|- align=left
| {{Template:UK-1Achates}}
|[[John Brown & Company]]
|
|14 Nov, 1912
|
| May, 1921
|- align=left
| {{Template:UK-Ambuscade}}
|[[John Brown & Company]]
|
|25 Jan, 1913
|
| Sep, 1921
|- align=left
| {{Template:UK-Christopher}}
|[[Hawthorn Leslie & Company]]
|
|29 Aug, 1912
|
| May, 1921
|- align=left
| {{Template:UK-Cockatrice}}
|[[Hawthorn Leslie & Company]]
|
|1912
|
| May, 1921
|- align=left
| {{Template:UK-Contest}}
|[[Hawthorn Leslie & Company]]
|
|7 Jan, 1913
|
|Torpedoed 18 Sep, 1917
|- align=left
| {{Template:UK-2Shark}}
|[[Swan Hunter]]
|
|30 Jul, 1912
|
|Sunk 31 May, 1916
|- align=left
| {{Template:UK-1Sparrowhawk}}
|[[Swan Hunter]]
|
|12 Oct, 1912
|
|Sunk 1 Jun, 1916
|- align=left
| {{Template:UK-Spitfire}}
|[[Swan Hunter]]
|
|23 Dec, 1912
|
| May, 1921
|- align=left
| {{Template:UK-Lynx}}
|[[London & Glasgow]]
|
|20 Mar, 1913
|
|Mined 9 Aug, 1915
|- align=left
| {{Template:UK-Midge}}
|[[London & Glasgow]]
|
|22 May, 1913
|
| Nov, 1921
|- align=left
| {{Template:UK-Owl}}
|[[London & Glasgow]]
|
|7 Jul, 1913
|
| Nov, 1921
|- align=left
| {{Template:UK-1Hardy}}
|[[John I. Thornycroft & Company]]
|
|10 Oct, 1912
|
| May, 1921
|- align=left
| {{Template:UK-Paragon}}
|[[John I. Thornycroft & Company]]
|
|21 Feb, 1913
|
|Torpedoed 18 Mar, 1917
|- align=left
| {{Template:UK-1Porpoise}}
|[[John I. Thornycroft & Company]]
|
|7 Jul, 1913
|
| Mar, 1921
|- align=left
| {{Template:UK-Unity}}
|[[John I. Thornycroft & Company]]
|
|18 Sep, 1913
|
| Oct, 1922
|- align=left
| {{Template:UK-Victor}}
|[[John I. Thornycroft & Company]]
|
|28 Nov, 1913
|
| Jan, 1923
|- align=left
| {{Template:UK-1Ardent}}
|[[William Denny & Brothers]]
|
|8 Sep, 1913
|
|Sunk 1 Jun, 1916
|- align=left
| {{Template:UK-1Fortune}}
|[[Fairfield Shipbuilding and Engineering Company]]
|
|17 Mar, 1913
|
|Sunk 31 May, 1916
|- align=left
| {{Template:UK-1Garland}}
|[[Cammell Laird]]
|
|23 Apr, 1913
|
| Sep, 1921
|}
</div name=fredbot:ships>

==Electric Logs==
It was ordered that these ships were to receive two [[Trident Electric Log]]s and one Charthouse Receiver sometime prior to March 1914, but the delivery date is unknown.{{AWO1914|967 of 27 Mar, 1914}}

==Performance==
The first ships completed steered very poorly.

{{UK-1Acasta}} took so long to turn through 8 points that only {{UK-1Mohawk}}, which was 10 feet longer, was slower to effect this.  Her advance of 596 yards was larger than all but those of 4 "Tribals".   {{UK-1Acasta}}'s diameters were 861 yards to starboard and 1097 to port &mdash; nearly twice that of the ''Acheron'' class's Yarrow special {{UK-1Firedrake}}.{{March|pp. 128-9}}

Things were so bad that comparative turning trials were ordered for {{UK-1Firedrake}} (rudder area 41.75 square feet) and {{UK-Christopher}} (46 square feet).  The issue was seen that a slight advantage for {{UK-Christopher}} in radius at lower (385 yards at 20 knots) fell apart at higher speeds (960 yards at 29 knots versus 490 yards for ''Firedrake'').  The ''Acasta'' class advance was worse at all speeds (295 versus 280 yards at 16 knots, degrading to 605 versus 375 at 29 knots).  It was determined that ''Christopher'''s response to additional helm disappeared past 20 degrees of helm, and further rudder seemed to actually worsen diameter up to 28.5 degrees and advance to 26 degrees at which point the rudder again became helpful.  She achieved her best diameter (785 yards) at 20 degrees helm, where her sister {{UK-1Achates}} had a whopping 1808 yards diameter.{{March|pp. 128-9}}

The suggestion was offered that the shape of the stern might be causing the problem, but a larger rudder or one with a plate on top of it were offered as less costly fixes than rebuilding the sterns.  The plate was chosen, but though the forensic trail goes cold, it seems something effective was done, as {{UK-Midge}}, {{UK-Lynx}} and {{UK-Owl}} had a reasonable 700 yard diameter at 33 knots.{{March|pp. 128-9}}

{{UK-1Ardent}} was most economical, burning 12.9 tons per hour. The average was 15.4 tons per hour.  With her semi-geared turbines, {{UK-1Garland}} burned 13.2 tons per hour, or 2.307 miles per ton as opposed to just under 2 miles per ton for the direct-drive turbines in the other ships.

On gun trials in rough conditions, it was found that the centre 4-in gun fouled the torpedo tube and enjoyed firing arcs of only 35 degrees.{{March|p. 127}}

==Armament==
Some of the ships were required to land their aft gun to accommodate depth charges.{{UKTHVol4Part34|p. 14}}

In late September, 1914, the Admiralty ordered that the guns on the [[Tribal Class Destroyer (1907)|Tribals]] and later classes were to be given loading lights, initially on temporary circuits.{{AWO1914|416 of 29 Sep, 1914}}

===4-in Guns (First 13 Ships)===
The first ships carried their 4-in guns on P. VII mountings.{{TheSightM|p. 83, 108, Plate 36}}

The mounting could elevate 20 degrees and depress 10 degrees, but its sight could only elevate 15 degrees and the range dial to 15 degrees (8,500 yards).  It recoiled 38 inches.<ref name=th15>''Technical History and Index'' Vol. 4, Part 34, p. 15.</ref>

These gear-worked sights had gearing constants of 26.67 and range dials for 2275 fps, and 1-in and .303-in aiming rifles.  M.V. could be corrected by a cam pointer allowing for a decrease to 2075 fps.<ref>The 2075 fps figure is inferred from similarity to P. IX sight and difference in range dial M.V..</ref>

It is unknown whether these were {{FTP}} sights.

The deflection gearing constant was 57.20 with 1 knot equal to 3.05 arc minutes, corresponding to 2275 fps at 2000 yards.  Drift was corrected by inclining the sight about pivot pins 2 degrees.

The layer's sight line was 12.5 inches above the bore, and 21.45 inches left.  The trainer's telescope sight line was 12.5 inches above and 17.4 inches right.

The sight had neither a temperature corrector nor a "C" corrector.<ref>No mention made, seems absent in Plate.</ref>

Both sides had an open sight.

Immediately before the war, a project to test "5 degree elevating gear" in {{UK-Cockatrice}}, {{UK-1Shark}} and {{UK-1Sparrowhawk}} that had stalled for some time when parts had been incorrectly machined was being expedited.  I would think that this gear was meant to provide sight elevations to match the mounts' limits of 20 degrees.{{AWO1914|147 of 17 July, 1914}}  The gear was issued three weeks later (to {{UK-1Acasta}}, {{UK-1Achates}} and {{UK-Christopher}} as well), and reports were requested on by the end of the month &ndash; a measure of the imperative of the war that had just started.{{AWO1914|236 of 7 August, 1914}}

===4-in Guns (Last 7 Ships)===
{{UK-1Garland}}, {{UK-Paragon}}, {{UK-1Porpoise}}, {{UK-Unity}} and {{UK-Victor}}, at least, carried three 4-in Q.F. Mark IV guns on P. IX mountings as in the following [[Laforey Class Destroyer (1913)#Guns|"L" class destroyers]].{{TheSightM|p. 80, 108, Plates 33, 34}}  The remainder of this section is copied from our section for the "L" class.

There were 120 rounds per gun. 

The mounting could elevate 20 degrees and depress 10 degrees, but its sight could only elevate 15 degrees and the range dial was actually only graduated to 12.5 degrees (7,900 yards).  "This was soon remedied by the supply of additional sight strips graduated to the extreme range of 10,200 yards."{{UKTHVol4Part34|p. 13}}  A photo of a weapon from {{UK-Lance|f=p}} on museum display shows that the range dial's markings to 10,200 yards required it to rotate through about 440 degrees &ndash; a revolution and a half.  That is, the range graduations were helical.<ref name=Hartley>[https://twitter.com/dhartley_NMRN/status/1164512882530422784/photo/1 photo] by Dave Hartley of the The National Museum of the Royal Navy.</ref>

These gear-worked sights had gearing constants of 26.66 and range dials for 2200 fps, and 1-in aiming rifle, though at least one was marked for 0.303 aiming rifle on its reverse.<ref name=Hartley/>  M.V. could be corrected by a cam pointer allowing for a decrease to 2000 fps.

Unlike some P. IX sights, these were not {{FTP}} sights.  The museum piece alluded to above shows that the range and deflection receivers were not even particularly convenient in their location.

The deflection gearing constant was 52.6 with 1 knot equal to 3.18 arc minutes, corresponding to 2200 fps at 2000 yards.  Drift was corrected by inclining the sight about pivot pins 2 degrees.

The layer's telescope sight line was 12.5 inches above the bore, and 21.45 inches left.  The trainer's telescope sight line was 12.5 inches above and 17.4 inches right.  Open sights were 13.3 inches above the bore and 24.35 inches left for layer and 20.3 inches right for trainer.

The sight had a temperature correcting scale plate and a "C" corrector.

The layer had an open sight.  The trainer's sight could be used as a [[Free Trainer's Sight|free sight]] with a counterweight.

During the war, some of the ships were required to land their aft gun to accommodate depth charges.{{UKTHVol4Part34|p. 14}}

As the midship 4-in mounting could train in a full circle and thus might break the electrical firing circuit wires, in June 1914 it was ordered that the pedestal to these guns have a warning plate fitted to them reading, "See circuits clear when training across limit stops."{{AWO1914|76 of 3 July 1914}}

In late September, 1914, the Admiralty ordered that the guns on the [[Tribal Class Destroyer (1907)|Tribals]] and later classes were to be given loading lights, initially on temporary circuits.{{AWO1914|416 of 29 Sep, 1914}}

===Other Guns===
In September 1916, {{UK-1Garland}} tested a P. IX trap-door mounting that could elevate a 4-in Mark IV gun 50 degrees in 1 minute 50 seconds.  {{UK-1Acasta}} and possibly some other ships also received this, probably on the midships or aft gun, although ''Acasta'' later surrendered hers in favour of an enhanced torpedo outfit.  Other units had a single 2-pdr pom-pom by 1920.{{March|p. 131}}<ref name=th15/>

===Doodling===
In a gun test for the forward gun using a whip hoist below and manual handling otherwise, one man in the magazine, one in shell room, one on the upper deck platform and one on the forecastle could supply 3 boxes of ammunition and 12 shells to the racks in two minutes.  The mid and aft guns without a hoist could do three boxes and 9 shells in 50 seconds.{{March|p. 128}}

===Torpedoes===
* two single 21-in tubes on the centreline

The height of the foremost tube above the deck required them to have a foldable platform pivoted on the stokehold to position abaft the tube to assist in "launching in" (loading) the torpedo.  This platform could be swung to either side of the deck and were high enough to pass over any spare torpedoes stored on the chocks.{{ARTS1912|p. 36}}  Concerns of visibility prompted instructions that provisions be made to guarantee clear arcs of 65 degrees to each side of the beam for the torpedo directors.{{ARTS1912|p. 37}}

In June, 1918, {{UK-1Acasta}} replaced her tubes with a double mounting Mark III another double Mark IV, losing her after gun, trap door mounting and searchlight.{{March|p. 131}}

===Other Weapons===
Early in 1918, {{UK-Cockatrice}} was fitted with depth charge throwers and rails capable of dropping 5 charges at 3 second intervals.{{March|p. 131}}

Addition of depth charges to these ships required some of them to land their aft gun.{{UKTHVol4Part34|p. 14}}

==Other Equipment==
In October 1914, as the ''Acastas'' were all serving in the {{UK-DF|4}}, they were ordered to have the (hydraulic?) searchlight control system first used in {{UK-Badger|f=p}} fitted.{{AWO1914|454 of 6 Oct, 1914}}

{{UK-Unity}} successfully tested an observation balloon in April 1918.  It was towed while escorting a convoy at 13 knots (40 knot wind speed at balloon) at an altitude of 300 feet.  It could be hauled down and up in as little as two to five minutes, eventually by moving the winch to the pom-pom platform from which crew could be easily exchanged.  842 miles of patrols were carried out with little need to refill the balloon.{{March|p. 131}}

In January 1918, {{UK-1Garland}} landed her midship tube and 4-in gun for a 24-ton lined acid tank for a smoke-generating apparatus.  The acid was vile and ate iron and steel, requiring the decks to be washed with 2 percent soda ash solution after each smoke making use.  Paintwork disappeared on first use.  The acid produced intense heat and dense white smoke when the acid contacted sea water.  About one quarter ton to one ton of acid per hour was used.  It was impossible to use with a following wind and people abaft the funnel had to wear a gas mask.  The system needed improvement, but was so effective that it was used at the [[Zeebrugge Raid]].{{March|p. 132}}

==Fire Control==
By 1915, at least, these ships also had fixed voice pipes installed between decks with the last lengths being flexible (one voice pipe for gunnery, one for torpedoes) fitted between bridge and guns, torpedo tubes, and searchlights.  A third voicepipe, entirely flexible, ran from bridge to the forward gun.<ref>''Manual of Gunnery, Vol. III., 1915.'', p. 150.</ref>

===Instruments===
By 1920, the ships in ''Acorn'' to ''Laforey'' classes had [[Wise Pressure Telegraphy System]]s in place to support fire control.{{UKTH34|pp. 15-16}}

===Rangefinders===
A 1-m base rangefinder was supplied to all destroyers of the "Tribal" class through "L" class around 1916, but this was later withdrawn.{{UKTH23|pp. 31, 32}}

==Torpedo Control==
[[File:ARTS1917Plate84.jpg|thumb|300px|'''Electrical Instruments'''{{ARTS1917|Plate 84}}<br>found in most or all "Acasta" class destroyers]]
A single sighting position was located high up in the centre of the bridge, thus requiring only a single set of firing pushes or keys as well as keys for operating a buzzer at the forward torpedo mount and a rattler at the aft mount.{{ARTS1917|p. 211}}

The data instruments used were electrical.  A single Mark I deflection transmitter at the control position, and separate order transmitters and keys, one for the forward tubes and one for the aft.  Each torpedo mount had a combined receiver for these signals.{{ARTS1917|p. 211, Plate 84.  (C.I.O. 439/17.)}}

==See Also==
{{WP|http://en.wikipedia.org/wiki/Acasta_class_destroyer}}

==Footnotes==
{{reflist}}

==Bibliography==
{{refbegin}}
*{{Conways1906}}
*{{March}}
*{{UKTHVol4Part34}}
{{refend}}

{{Footer Acasta Class Destroyer (1912)}}

{{DEFAULTSORT:Acasta}}

{{CatClassDestroyer|UK}}


<!-- data

nat=UK
cat=Destroyer
type=destroyer

chain=Destroyers

{group
name=Admiralty Design
}

{ship
name=Acasta
pend=H.59 (1914)<br>H.00 (Jan 1918){{DittColl|p. 63}}
builder=[[John Brown & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=10 9 1912{{DittColl|p. 63}}
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Achates
pend=H.46 (1914)<br>H.01 (Jan 1918){{DittColl|p. 63}}
builder=[[John Brown & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=14 11 1912{{Conways1906|p. 75}}
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Ambuscade
pend=H.62 (1914)<br>H.05 (Jan 1918){{DittColl|p. 63}}
builder=[[John Brown & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=25 1 1913{{Conways1906|p. 75}}
comm=
fatedate=9 21{{Conways1906|p. 75}}
}

{ship
name=Christopher
pend=H.51 (1914)<br>H.25 (Jan 1918){{DittColl|p. 63}}
builder=[[Hawthorn Leslie & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=29 8 1912{{Conways1906|p. 75}}
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Cockatrice
pend=H.73 (1914)<br>H.26 (Jan 1918){{DittColl|p. 63}}
builder=[[Hawthorn Leslie & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=1912
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Contest
pend=H.63(1914)<br>H.28 (1917){{DittColl|p. 63}}
builder=[[Hawthorn Leslie & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=7 1 1913{{Conways1906|p. 75}}
comm=
fate=Torpedoed
fatedate=18 9 17{{Conways1906|p. 75}}
fate2=in English Channel{{Conways1906|p. 75}}
}

{ship
name=Shark
pend=H.04 (1914){{DittColl|p. 63}}
builder=[[Swan Hunter]]{{Conways1906|p. 75}}
order=
laid=
launch=30 7 1912{{Conways1906|p. 75}}
comm=
fate=Sunk
fatedate=31 5 16{{Conways1906|p. 75}}
fate2=in [[Battle of Jutland]]
}

{ship
name=Sparrowhawk
pend=H.61 (1914){{DittColl|p. 63}}
builder=[[Swan Hunter]]{{Conways1906|p. 75}}
order=
laid=
launch=12 10 1912{{Conways1906|p. 75}}
comm=
fate=Sunk
fatedate=1 6 16{{Conways1906|p. 75}}
fate2=in [[Battle of Jutland]]
}

{ship
name=Spitfire
pend=H.41 (1914)<br>H.1A (Jan 1918){{DittColl|p. 63}}
builder=[[Swan Hunter]]{{Conways1906|p. 75}}
order=
laid=
launch=23 12 1912{{Conways1906|p. 75}}
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Lynx
pend=H.71 (1914){{DittColl|p. 63}}
builder=[[London & Glasgow]]{{Conways1906|p. 75}}
order=
laid=
launch=20 3 1913{{Conways1906|p. 75}}
comm=
fate=Mined
fatedate=9 8 15{{Conways1906|p. 75}}
fate2=in Moray Firth{{DittColl|p. 63}}
}

{ship
name=Midge
pend=H.13 (1914)<br>H.40 (Sep 1915)<br>H.79 (Jan 1918){{DittColl|p. 63}}
builder="
order=
laid=
launch=22 5 1913{{Conways1906|p. 75}}
comm=
fatedate=11 21{{Conways1906|p. 75}}
}

{ship
name=Owl
pend=H.31 (1914)<br>H.93 (Jan 1918){{DittColl|p. 63}}
builder="
order=
laid=
launch=7 7 1913{{Conways1906|p. 75}}
comm=
fatedate=11 21{{Conways1906|p. 75}}
}

{group
name=Thornycroft Specials
}


{ship
name=Hardy
pend=H.67 (1914)<br>H.39 (Jan 1918){{DittColl|p. 63}}
builder=[[John I. Thornycroft & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=10 Oct, 1912{{DittColl|p. 63}}
comm=
fatedate=5 21{{Conways1906|p. 75}}
}

{ship
name=Paragon
pend=H.26 (1914){{DittColl|p. 63}}
builder=[[John I. Thornycroft & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=21 2 1913{{Conways1906|p. 75}}
comm=
fate=Torpedoed
fatedate=18 3 17{{Conways1906|p. 75}}
fate2=in [[Dover Straits Action]]
}

{ship
name=Porpoise
pend=H.27 (1914)<br>H.95 (Jan 1918){{DittColl|p. 63}}
builder=[[John I. Thornycroft & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=7 7 1913{{Conways1906|p. 75}}
comm=
fatedate=3 21{{Conways1906|p. 75}}
fate2=to Brazil{{Conways1906|p. 75}}
}

{ship
name=Unity
pend=H.68 (1914)<br>H.5A (Jan 1918){{DittColl|p. 63}}
builder=[[John I. Thornycroft & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=18 9 1913{{Conways1906|p. 75}}
comm=
fatedate=10 22{{Conways1906|p. 75}}
}

{ship
name=Victor
pend=H.36 (1914)<br>36 (1915)<br>H.6A (Jan 1918){{DittColl|p. 63}}<ref>R. A. Burt.  ''British Destroyers in World War One'', Photo 66.</ref>
builder=[[John I. Thornycroft & Company]]{{Conways1906|p. 75}}
order=
laid=
launch=28 11 1913{{Conways1906|p. 75}}
comm=
fatedate=1 23{{Conways1906|p. 75}}
}

{group
name=Other Specials
}

{ship
name=Ardent
pend=H.78 (1914){{DittColl|p. 63}}
builder=[[William Denny & Brothers]]{{Conways1906|p. 75}}
order=
laid=
launch=8 9 1913{{Conways1906|p. 75}}
comm=
fate=Sunk{{Conways1906|p. 75}}
fatedate=1 6 16{{Conways1906|p. 75}}
fate2=at [[Battle of Jutland]]
}

{ship
name=Fortune
pend=H.30 (1914){{DittColl|p. 63}}
builder=[[Fairfield Shipbuilding and Engineering Company]]{{Conways1906|p. 75}}
order=
laid=
launch=17 3 1913{{Conways1906|p. 75}}
comm=
fate=Sunk
fatedate=31 5 16{{Conways1906|p. 75}}
fate2=at [[Battle of Jutland]]
}

{ship
name=Garland
pend=H.32 (1914)<br>H.36 (Jan 1918){{DittColl|p. 63}}
builder=[[Cammell Laird]]{{Conways1906|p. 75}}
order=
laid=
launch=23 4 1913{{Conways1906|p. 75}}
comm=
fatedate=9 21{{Conways1906|p. 75}}
}


data -->

[[Category:Featured Ship Classes]]