Subsea Cable Testing and 4 other types of verification: the Design Compliance Matrix

Verifying the required specifications is perhaps the most crucial part of designing a naval subsea cable. After all, as an engineer, you must be able to prove that the cable works as it is supposed to. There are five different ways of verification, one of which is subsea cable testing. 

At DeRegt, we use a Design Compliance Matrix (DCM) as the foundation for the verification process. This way, you know that all of your specifications are thoroughly verified. This blog explains how a DCM works and what verification methods there are, including examples.

How the Design Compliance Matrix is built for subsea cable testing and more

The Design Compliance Matrix first describes the scope of the project. Here it is defined what the cable request entails and what the purpose of the Design Compliance Matrix is: what needs to be verified?

The project's background is also thoroughly described in the next chapter, where we include more about the subsea project in the DCM and whether there are any peculiarities. For example, when it comes to the winch or the termination. 

The Matrix of Conformity is the most essential part of the DCM. All specifications of the subsea cable are listed here. In the columns after the specifications, it is specified how these will be verified. 

5 Verification Methods within your DCM

There are five possible verification methods within the Design Compliance Matrix. The first column lists whether the qualification is done by Inspection (I), Analysis (A), or Demonstration (D). Subsea cable testing (T) is listed below as either Qualification Test or FAT, describing when the test(s) occur. The fifth verification method is the Certificate of Conformity. 

These verification methods are defined in detail within every DCM, together with used abbreviations. This way, the reader can always double-check what is stated about the specification and its accompanying verification method. 

Important to know is that verification methods can also be combined. For example, if something is analyzed in an early stage of the design process, a demonstration might be required to verify it. 

Below, we’ll define the five verification methods and give examples for each of them. 

1. Inspection (I)

The first verification method is Inspection. Specifications that can be verified by inspection, are checked visually or by dimensional checking. This relies mainly on the human senses (sight and touch), but basic measurements or handling methods are sometimes used. For example, Inspection can be done with a meter rule or a microscope.

An example of Inspection is the cable diameter measurement. The cable drawing is inspected in the early stages of the design process. Is the diameter as big as specified? At the FAT, the final product is inspected again. By comparing those inspections, the specification “cable diameter” is verified.

2. Demonstration (D)

For operational characteristics, often a Demonstration is required for verification. These specifications can be observed on the running item without needing physical measurements. 

For example, the start-up sequences or a built-in test device can be demonstrated by simply running the product and verifying that the specifications are being met. 

3. Analysis (A)

The A for Analysis is listed behind all specifications that can be verified by analytical evidence. There is a lot of data on materials and surroundings, often sufficient for verification. That’s why analytical evidence is obtained by calculation, without any intervention on the item itself. The techniques used are modeling, simulation and prediction. 

For specifications that can be verified by Inspection, Demonstration or Analysis, subsea cable testing is often not necessary and even unnecessarily expensive. However, sometimes subsea cable testing is crucial for properly verifying compliance to all specifications.

4. Testing (T)

Within the DCM, subsea cable testing is defined as a “Check of measurable functional characteristics, accessible directly or indirectly”. As stated before, subsea cable testing can occur in the qualification testing phase or at the Factory Acceptance Test (FAT). 

There are various qualification tests (you can find some common examples in this blog). Other specifications are standardly tested in the FAT. For example, all electrical components will be tested at the FAT. Can they handle the number of volts stated in the specifications? This can only be verified by testing, as inspections or analyses are insufficient. The same is true for optical components, these will also be standardly tested in the FAT.

5. CoC (C)

The CoC is an abbreviation for Certificate Of Conformity. This verification method is used for materials or components that other parties supply. Quite often, these materials or components have been tested or analyzed before shipping, so it would be a waste of time and resources to test or analyze them again. The CoC is a certificate that shows the material's or component's conformity.

For example, if we use steel wires as armoring, we want the steel to have a specific strength. The supplier has to comply with this and sends us a CoC. This certificate states its specifications. For example, it is galvanized steel and meets our requested strength.

Making your naval subsea project a success

The Design Compliance Matrix is an important part of our design process, as it forms the guideline for proper verification of all specifications. To make your naval subsea project truly successful, there are other important factors to consider.

That’s why our sonar cable experts wrote The Complete Guide on Sonar Cables and Subsea Defense Projects. In it, you read more about:

• Various Underwater Defense Solutions
• Sonar Cable Specifications
• Subsea Cable Testing for Sonar Systems

Download your copy of The Complete Guide here and gather all information on naval defense in one place:

With all other questions about your cabling needs, you can contact my colleagues or me here. Our cable experts are always happy to help, advise or guide you in all your cable requirements.