The introduction of nuclear power plants and the teardrop shaped hulls to US nuclear submarines in the late 1950s slightly overshadows one other important development in undersea warfare at that time. Sonar arrays on submarines became increasingly large. The size of an array is directly linked to the wavelengths they operate on. Larger arrays allow use of lower frequencies. And lower frequencies generally propagate further through water than higher frequencies. This, coupled with advances in passive sonar signal processing, extended the detection range against submarines from around 4000 yards to 50,000 or even sometimes 100,000 yards, or 25 to 50 nautical miles.

The increase in detection range called for an increase in weapons range. There was a limit to just how far a conventional torpedo might travel. Further, at long ranges, while a target might be detected, the precision of the plot was rather poor.

And so, like many other programs in the late 50s and early 60s, the answer was nuclear weapons. Where surface ships could use DASH to prosecute long range targets, submarines would have to use something that could be launched from a torpedo tube.

The answer was SUBROC, or Submarine Rocket, the UUM-44 underwater to underwater guided missile. Development began in 1958, and by 1965, it was deployed to the fleet. After being ejected from a torpedo tube, a solid rocket motor would drive it to the surface. The missile’s inertial navigation system would follow a precalculated ballistic trajectory. At the calculated time, the booster would be separated, and the warhead would continue to the impact point. There it would sink and then its W55 5 kiloton warhead would detonate.


Unlike ASROC, SUBROC never carried a torpedo payload. It was only available as a nuclear weapon. While training and testing rounds were fired, no actual nuclear testing of an operational warhead were ever conducted.

SUBROC was deployed until 1989, with the end of the Cold War. A proposed follow on weapon armed with a torpedo, Sea Lance, was cancelled due to technical issues, cost overruns, and the perceived reduction of the submarine threat after the collapse of the USSR. Today’s US Navy submarine force relies solely on the M48 torpedo for anti-submarine warfare.

3 thoughts on “SUBROC”

  1. The Mk-113 fire control system could be programed with a post launch own ship maneuver that would lead to the determination of (I’m not making this up) Own Ship Damage (LIGHT/MODERATE/SEVERE) after weapon detonation. Face it, you couldn’t shoot it at anything you couldn’t hear. Never saw more than two nucs in the torpedo room. Usually a SUBROC and a Mk-45 ASTOR (which was a wire guide and even more problematic than SUBROC).

    So I sez to the chief – “Hey chief, how come we got us four 4FZ slots and only two nuc fish in the room?”
    The chief sez – “Son, you will never be on an attack boat that carries more than two nuclear weapons.”
    “Why is that chief?”
    “We carry the second one in case the first one doesn’t work.”

    Speaking of nuclear weapons launched from attack submarines, I fondly remember the Regulus Missile:
    You should spring for the whole documentary (it’s a real hoot). What Regulus lacked in precision, it made up for in warhead yield (10MT).

    Jealous of the submarine force’s nuclear strike capability, the skimmer navy decided that they needed to get into the act. The value added was that they would send in two fighters to escort the weapon and to make sure that it got to the target. The full documentary has an interview with two of the fools who were selected to fly that mission. I refer you back to my conversation with the chief.

    1. USS Long Beach was originally designed to have a four pack of Polaris tubes amidships, where the ASROC launcher eventually ended up.

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