Navy

Reinforced snap hook with dual-direction spring latch

Strong yet lightweight design for safely launching and recovering heavy objects

Military Technology Other

U.S. Navy engineers have invented a novel snap hook for launching and recovering large underwater drones. The patented mechanical device is available via license agreement to companies that would make, use, or sell it commercially.

Navy personnel launch a MK18 autonomous underwater vehicle. (Blake Midnight/Navy)

The MK18 Kingfish UUV is large, heavy and the Navy uses a cable winch to launch and recover it.

Using a common steel snap hook, attaching or detaching the cable to the MK18 requires a sailor to lean and reach out of the boat with their hands while other sailors steady the UUV with gaffing poles. This is a challenging task in rough seas and comes with some risk of injury.

Commercially available hooks with dual direction latches are not rated for the necessary weights, according to the Navy.

This led the engineers to design and test their own hook, which can be attached to the load for recovery using a handheld pole.

Illustration of U.S. Patent 9,994,430.

In one version, the bent wire acts as the latch and spring. When the latch is bent in either direction the difference in radii of the wire causes a spring effect to oppose any motion.

The latch guard and stop prevent the latch from getting pulled out of the hook. It also provides an end stop from over opening the latch.

Illustration of U.S. Patent 10,436,241.

To launch the load after it is positioned in the water the mainline is made slack and the secondary line is pulled, which pivots the load onto the latch for release.

The hook may be made of aluminum, titanium, 15-5 stainless steel, 17-4 stainless steel, carbon fiber, or carbon steel.

One version of the Navy’s snap hook weighs less than 300 grams and was designed specifically for launch and recovery of 1,000-pound loads with a 2X safety factor.

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