perisher
05-03-07, 10:36 AM
I had a conversation today with a work colleague who served in British conventional subs in the '60s and '70s. His father served in subs in WWII.
I asked his opinion on the rate of fire that could be achieved with the deck gun. His answer was, "Surprisingly high." He said that his father claimed 10 to 12 rounds per minute on a 4 inch gun, but, (and this is a big but), only on those classes with a gun tower, such as the T, S and A boats. The technique was to approach the target, anything from a ship to a coastal railway, at periscope depth. The gun's crew all taking a good look at the target before getting into position under the gun tower hatch. Meanwhile ammunition was moved from the magazine to the wardroom, which was just below the gun tower. Compressed air was released into the boat to create a significant over pressure inside the hull. As the boat arrived at the firing point the captain would take a range and bearing to the target and order, "Surface". He would then give the gun layer the range and bearing and the order to commence firing. When the boat was still a few feet below the surface the first lieutenant would blow his whistle and the conning tower and gun tower hatches would be opened and the bridge and deck crews would climb out in the bubble of escaping air. The gun layer and sight-setter would train on the range and bearing given while the first round was being loaded and it would leave the gun before the deck was clear of the water. They could then fire as fast as the ammunition could be passed up the tower.
However, boats without gun towers, U, V and late model A boats, had to send up crew and ammunition via the conning tower. Manning the gun would take up to a minute and the rate of fire would be about 5 or less. He believed that a U Boat, due to its less elaborate ammunition supply system would be hard pushed to achieve 2 rounds per minute, with any kind of sea running.
As for US boats, he says it would be down to the ammunition supply again. Those boats that had chutes or tubes through the pressure hull for ammunition delivery could probably manage about 6 rounds per minute, while those whose ammunition had to come up the conning tower would be able to fire about 3 rounds per minute. The British boats were a little faster because the upper and lower conning tower hatches were in line with each other.
He added that rate of fire was only important when engaging a target when you needed to strike fast and be away before the enemy could react, as in destroying a bridge on a coastal railway. It is of little importance when using the gun in its traditional role of finishing off a target well out at sea, as no sub skipper in his right mind would use the gun for that unless he was sure his sub would be safe.
I asked his opinion on the rate of fire that could be achieved with the deck gun. His answer was, "Surprisingly high." He said that his father claimed 10 to 12 rounds per minute on a 4 inch gun, but, (and this is a big but), only on those classes with a gun tower, such as the T, S and A boats. The technique was to approach the target, anything from a ship to a coastal railway, at periscope depth. The gun's crew all taking a good look at the target before getting into position under the gun tower hatch. Meanwhile ammunition was moved from the magazine to the wardroom, which was just below the gun tower. Compressed air was released into the boat to create a significant over pressure inside the hull. As the boat arrived at the firing point the captain would take a range and bearing to the target and order, "Surface". He would then give the gun layer the range and bearing and the order to commence firing. When the boat was still a few feet below the surface the first lieutenant would blow his whistle and the conning tower and gun tower hatches would be opened and the bridge and deck crews would climb out in the bubble of escaping air. The gun layer and sight-setter would train on the range and bearing given while the first round was being loaded and it would leave the gun before the deck was clear of the water. They could then fire as fast as the ammunition could be passed up the tower.
However, boats without gun towers, U, V and late model A boats, had to send up crew and ammunition via the conning tower. Manning the gun would take up to a minute and the rate of fire would be about 5 or less. He believed that a U Boat, due to its less elaborate ammunition supply system would be hard pushed to achieve 2 rounds per minute, with any kind of sea running.
As for US boats, he says it would be down to the ammunition supply again. Those boats that had chutes or tubes through the pressure hull for ammunition delivery could probably manage about 6 rounds per minute, while those whose ammunition had to come up the conning tower would be able to fire about 3 rounds per minute. The British boats were a little faster because the upper and lower conning tower hatches were in line with each other.
He added that rate of fire was only important when engaging a target when you needed to strike fast and be away before the enemy could react, as in destroying a bridge on a coastal railway. It is of little importance when using the gun in its traditional role of finishing off a target well out at sea, as no sub skipper in his right mind would use the gun for that unless he was sure his sub would be safe.