Conway Maritime Press - Warship 44

i
iculars on 1 December 1938 at an estimat€d
cost of f400,000 per vessel. On
the 3fth, approval was given to orderten
vessels. However, the order for the second
group of ten vessels was to be delayed
pending the evaluation ofthe alternative
design armed with torpedoes.
The functions of the vessels were listed
under the staff requirement for the 1939
fast escort vessel (ADM I/9440):
o
r
o
e
To supplement existing vessels on
A/S and A,/A escort duties.
To provide A/S and A,zA escort for
fast transports and detached units
of the fleet.
For use at home and abroad.
The vessels could be used fortraining
in peacefime.
The Initial Building
Programme and Problems
Tenders, to be received by 20 January
1939, were invited on 20 December 1938.
However, all the firms asked to tender
said that the Engineer-inchiefs estimate
of 270 tons for machinery was 30 tons too
low. It was agteed to use 285 tons. Second,
the legend hull weight was stated as 450
tons (despite the detailed calculation of
495 tons). The shipbuilders suggested 475
tons and finally a figure of 460 tons with a
margin of ten tons was agteed. By using
D quality steel, the shipbuilders saved 13
tons ofhull weight, leaving the design 14
tons overweight compared with the
revised estimate of 460 tons.
A second problem arose when the
stability of the vessels was checked and
found to be 0.8 feet lower than originally
calculated. After discussions with the
builders, the beam of the vessels was
increased by 9in to 29 feet on 14 February
1939. The extra beam increased the hull
weight by five tons and the full load by 7
tons as the tanks got bigger. The speed of
the vessels was reduced by 0.1 hrots.
On 14 March 1939. the First Sea Lord
{irected that in order to speed production,
the second batch of ten vessels were to be
repeats ofthe first ten. A week later, the
first ten were ordered, to be followed
quickly by the ordering of the second
batch of ten vessels on 11 April 1939. the
first units of the class were laid down on 8
June 1939 on the expiry of TYeaty
obligations. Progress was rapid with 18
vessels being laid down before the
declaration of war and, Atherstone,
Hambledon and Eglintonbeing launched
before 1939 had closed.
Athe r s to ne's St ab ility
Problems
Atherstone was nearing completion and
as usual an inclining experiment was
undertaken to check the weight and the
It would seem that the detailed calculations
of her stability had been repeated
and a serious error found. Goodall noted
in his diary: "Cole came in with
Atherstone's inclining results. GM 1 foot
'tion, less than calculated. bad errorin calculashall
have to do something drastic."
After an investigation, the reasons for
this error were discussed. First there was
an original error in the preliminary calculation
for the KG ofthe hull structure and
fittings (it appears that the upper deck
was taken as 7 feet above the keel instead
of 17 feet). This was responsible for twothirds
of the loss of stability. Second, the
vessels turned out to be 60 to 70 tons
heavier than estimated. This should have
been expected, especially in light of the
problems raised by the builders the
previous year. This increase in weight
was responsible for the other third of the
loss of stability.
The vessels were altered in the following
ways to restore stability:
o No 2 4in twin mounting was
landed.
o The funnel and bridge were cut
down to reduce top weight.
e 52 tons of permanent ballast was
fitted.
In fact, 23 vessels had to be altered this
way, as three vessels of the second group
(ordered in September and December
1939), Blencathra, Brochlesby and Liddesdale,
were already too far advanced
to be widened and received modifications
similar to those affected to the first
group.
It would seem that the stability
problems that arose in Atherstone werc a
result of the pressure being placed on
naval constructors during 1938 and 1939.
Supervision was inadequate and the
head of section must be to blame for not
checking the design of the new class
against the Blqck Swan cfass, also armed
with-three twin 4in guns on a beam of 37
feet. Second, there were inadequate
checks on the weights to be used in the
design.
The Deuelopment of the
Type 2 Vessels
To speed up production, these 36 vessels
had originally been ordered as repeats of
the original group. These vessels, except
for those mentioned earlier, incorporated
the following alterations to improve
stability:
r
The beam of the vessels was
increased by 2 feet 6in to 31 feet 6in.
It is believed that some vessels
were
'kippered'
on the slip to
incorporate the required beam, by
widening shell strakes.
o
further aft.
The funnel was lowered'
As a result of these modifications no
permanent ballast was shipped. Further
changes were made to these vessels to
enhance their anti-aircraft provision, by
fitting a quadruple 2-pounder and two
single 20mm Oerlikon. The specifications
of the Tlpe 2s were as follows:
kngth: 280 feet (oa) 264 feet &etween pp)
Beam: 31[ feet
Displacement: 1050 tons (standard), 1430
tons (deep)
Armament: Six 4in (3x2), One 2-pounder
quadruple pom pom, two 20mm and 50
depth charges with one rail and two
throwers.
Max Speed: 25 knots (deep load) with
19,000sHP
Endurance: 2560 miles at 20 knots
Complement: Nine officers, 155 ratings
Ttre revised gxoup weights were:
Hull:
595 tons
Machinery: 295 tons
Armament: 136 tons
Equipment: 111tons
Oil Fuel:
277 tons
RFW:
16 tons
Deep displacement: 1430 tons
The Type 3 Vessels
By the spring of 1940, it had become clear
that the Hunts would be undertaking
fleet duties and would require a torpedo
armamerit, albeit at the expense of
suppressing part of the gun armament.
This proposal was, in effect, a revival of
the idea to arm the second batch of ten
vessels of the 1939 Programme with
torpedoes.
At a meeting held on 26 March l.940the
following parameters of the design were
accepted:
The ships were to have a beam of
3lL/2 feet and it was hoped that a
speed of 27 knots in deep condition
could be achieved.
The quarter deck 4in mounting
was suppressed.
It.was hoped to ship 100 depth
charges, with four depth charge
chutes'and four depth charge
throwers being provided, butitwas
accepted that two throwers only
might have to be tolerated.
Better protection ofthe bridge and
wheelhouse, as well as depth
charge personnel was to be
provided.
TWo designs were produced in April 1940:
A: Four 4in guns, one set of twin tubes on
2t9