Towed Sonar Array Cables and other Underwater Defense Solutions

As an engineer in the defense market, you often have to deal with customers with many specifications and requirements. Many of these requirements have to flow down on the different components of your project – like in the (sonar) cable.

Often, this involves looking at international norms, standards and MIL-SPECs. If you need to know about all these requirements, you will have to go through a lot of research.

Don’t worry, as an engineer you don’t need to know everything about every single component. After all, you have partners who can help you with this and know all the MIL-SPECs for their components. On this page, we look at various cable solutions for naval systems and you will find information about specifications, testing, and validation of these cables.

Types of Sonar Cables: variable depth sonar vs towed array sonar

There are several naval systems that use underwater defense cables. Designing a cable for these different systems requires a different approach for each system. For example, underwater cables are being used in Mine Counter Measure applications. One of the biggest markets in underwater defense is sonar. The two main sonar systems are Hull Mounted Sonar (attached to the ship) and Towed Sonars (towed underwater).

In fact, there are two main types of towed sonar systems:

variable depth sonar
towed array sonar

Which questions should you, as an engineer, ask when selecting a cable for these sonar systems? Let’s compare variable depth sonar vs towed array sonar.

Variable Depth Sonar

Variable Depth Sonar is a system used to search for submarines at various depths. The right range is needed to detect an opposing submarine, so flexibility is key for these systems. Therefore, they use a long cable on the winch, which can be deployed at different lengths. It can be rolled out to search in deeper waters and taken in to search in shallower waters.

A Variable Depth Sonar system consists of multiple cables. The cable that tows the sound source or towed body is called the Heavy Tow Cable. This is a special cable, as it needs to be as heavy as possible to reach the operational depth. Therefore, it always has steel armor, and usually fairings as well. Fairings are plastic parts mounted around the cable, which make the cable more hydrodynamic. Streamlining the cable is necessary because sailing at a high speed will make certain depths impossible otherwise. A neutrally buoyant Tow Cable is also an integral part of these systems. The neutrally buoyant Tow Cable is often towed behind the sound source or towed body and remains continuously at the same depth.

Towed Array Sonar

As you can see in the image, the Towed Array Sonar system includes only that last cable: a neutrally buoyant Tow Cable carried behind the submarine. With a towed array sonar system, the cable must be constantly kept at the same depth. This means that the cable must have the same density as seawater so that it weighs precisely zero kilograms underwater. This is quite challenging, as seawater is not equally heavy everywhere; it depends on salinity, temperature, and pressure.

3 Advantages of Early Supplier Involvement in your Defense Project

Whether you are composing a towed array sonar system, a variable depth sonar or another underwater defense system; they all have in common that they consist of various components. As an engineer, it is hard to know everything about every component.

Involving suppliers at an early stage of the project makes sure you have partners with the right knowledge on board. And that’s not all; Early Supplier Involvement has even more advantages for your project, making your job easier.

Developing more efficiently
Identifying optimisation chances at an early stage
Reducing overall costs of components

Making sure the cable perfectly fits your Towed Sonar System: Testing and Validating

As mentioned, it is important to work with experts in specific components (such as the cable), who know the various International standards and who ensure that the components they supply meet all the requirements – and can also be demonstrated to do so. In this way, you receive optimal support as a defense engineer.

Of course, as the person responsible for the project, you want to be in control. For this reason, it is important that your partners look at the requirements and can demonstrate the impact of certain choices on the project. This is where DeRegt’s experts come in; they like to work together with engineers on a thorough result.

Important to know: the focus of all these standards in sonar systems is usually on electronics. Are they suitable for certain environments and do they meet safety requirements? In our towed sonar cables, there are usually no chips or electronics, which means that many standards are less relevant.

The most important thing for a successful defense project and the presentation of it to your end customer is the verification of standards and requirements. For defense projects, this often results in a very extensive verification document. Verification can be divided into two parts: analysis and testing.