On 10 October 1942, USS Idaho
(BB-42) was the subject of an unusual test to determine the ability of
the older battleships to maintain a rate of fire over a prolonged period.
During this test, she fired 100 rounds from each of her six forward guns
in 156 salvos. Most of these were fired at a range of 21,000 yards
(19,200 m), but the range varied from 19,000 to 28,000 yards (17,370 to
25,600 m) and some salvos were air spotted. The sea state was calm
and she maintained a speed of about 15 knots during the test. The
test was observed by no less than eight BuShips and four BuOrd observers
along with the CinCPAC gunnery officer and eight Army officers from the
Western Defense Command. The Navy also used this opportunity to train
thirty-five battleship officers in spotting techniques, which probably
slowed down the firing cycles.
The New Mexico class (BB-40), of which
USS Idaho was a member, carried 300 projectiles per turret with 67 of these
on the turntable, 185 on the fixed structure of the shell deck, 30 in the
lower handling room and 18 in the lower shell circle in the fixed stool
structure immediately below the turret shell deck. After the turrets
were modified in the 1930s to increase their maximum elevation, these latter
shells were difficult to access as they had to be first lowered into the
lower handling room before they could be hoisted to the gunroom.
This modification also hampered the propellant supply, with bags being
passed by hand into the lower handling room and then taken by hand to the
upper handling room where they were transferred into upper hoists discharging
into transfer rooms and the loading level, where four bags were sent from
each of two hoists to the wing guns and two bags from each hoist to the
center gun.
This complex system worked well during
the test, even though ammunition supply depended largely upon muscle power.
Only five times before the 148th salvo did any gun fail to fire because
it lacked powder and only once because a projectile was not available.
BuShips commented that "for a good portion of the time, shell and powder
handling lines were crossing each other in the lower powder handling room
without causing any confusion. In fact, the flexibility of the powder
handling system was most impressive, especially with the relatively green
crew manning these stations. . . . 2,400 bags of powder were handled without
any breakage. Considerable strength and dexterity were exhibited
by shell handlers as they 'walked' the projectiles to any desired location
by rocking and turning the shells so their points moved in a horizontal
circle of about 6 inch diameter. This indicates the importance of
acquired skills in any ammunition handling problem."
During the 156 salvos fired for the test,
only for twenty salvos did all six guns fire together. Forty-seven
salvos had five guns. There were twenty-two four gun salvos, thirty-one
three gun salvos, twenty-five two gun salvos and eleven 1 gun salvos.
The average interval between salvos was 1 minute and 24 seconds.
One five gun salvo was fired forty-nine seconds after the last one.
Salvos sixty to eighty, which were primarily of five guns, were fired at
an average interval of sixty-seven seconds. By the end of the exercise,
with both projectiles and propellant having to be transferred from the
farthest corners of the shell and powder rooms, salvo firing was delayed
and the average interval for salvos 148 to 156 was two minutes. These
last salvos were almost all of one gun.
Besides the problems of these last salvos
with slow supply of ammunition, ammunition supply was considered satisfactory,
with only five salvos prior to 148 having any gun failing to fire due to
lack of propellant and only one salvo having a gun failing to fire due
to lack of projectile. "Guns generally failed to fire for minor reasons:
the need to adjust or replace a gas check pad (seventy-eight times); the
need to adjust a rammer (seventy-five times); or a misfire (thirteen times)."
Based upon this test, BuShips concluded
that the magazine arrangements of the old battleships were satisfactory,
although it had reservations about the performance of the system in heavy
weather.
Shortly after this exercise, Idaho entered
Puget Sound Navy Yard to be regunned.
