I-VMS Rectification Proposal


Response sent to MMO with more detailed information on proposal to fix issues

Date: 19th May 2023

1          Overview

In a letter on 13 March 2023, the MMO requested a proposal to fix the issues raised in independent test.

Our proposal on 17th March 2023 was considered lacking in detail.

As requested in a meeting on 18th May 2023, the details below are to answer all questions raised in more detail.


The MMO report including the detailed results of testing for the MS44 device. At a high level the testing undertaken by GMV NSL identified issues with the device, specifically:

  1. IP67 Status
  2. Blackout Performance
  3. Missing Status code messaging

2          IP67 Status

With GNV permission we consulted with the MS Testing, who carried out the test. Maritime Systems used this company for our approval testing.


In consultation with the company who carried out the IP67 test, it was concluded that the speaker aperture is the weak spot in the design.


It uses a waterproof film patch on the inside the housing to seal the device whilst still allowing sound to resonate through the fabric.

In the IP67 specification some ingress of water is allowed, but the testing institution considered our ingress in the test above acceptable limits.

We accept this decision.


It was noted by GMV that there is also a microphone hole that may have contributed to the leakage, but this is not an open aperture, and is not a risk of failure. It is an external feature that remains in the mould for the device from previous iterations not used in the I-VMS program. It does not lead to an open aperture.


Initially we were using the speaker as a method of signalling operation status to the users, hence why the feature is in the housing.

However, now we are no longer using this method, instead relying upon the lights to rely operational information.


Rectification overview

We will produce am adhesive waterproof vinyl patch that is added to the external surface of the housing, sealing the speaker aperture.

When submerged, the positive pressure of the surrounding water will act to increase the sealing effect of the patch over the openings.

In conjunction with the internal patch this will provide a double defence against water ingress and will be satisfactory to prevent a future test failure.

Patch Design

The patch will be manufactured from F Mat 44 Autotex V200 Polyester, with 3m 468 adhesive.

We have used this material and adhesive for our military projects for many years to seal open apertures of a similar nature.

The patch will be manufactured by CCL Design in Chippenham. They are experts in this product and supply many military and commercial projects that require similar parts.

Mounting of Patch

The patch is supplied with the adhesive attached and with a backing strip.

The application area on the device is cleaned and dried.

The strip is removed and the patch applied to the device.

Hard finger pressure is maintained  on the patch for a 5 seconds to ensure correct adhesion.


Patch Dimensions

The patch will be 20mm diameter, and red in colour to make visible check of its fitment easy.



 Time to implementation

1 week for Manufacture of prototype for testing

1 week for IP67 testing by MS testing. (quoted at £400, 1 week for completion)

2 weeks for manufacture of 2000 patches

2 weeks for distribution and fitment by engineers around England.


Method of implementation

The patches will be manufactured and distributed to our network of engineers, for installation on all vessel with a MS44 device.


Using our engineers app, they will record and take pictures of all installations, so that progress can be monitored and evidence supplied to MMO.


3          Tamper Indicator

The MS44 has an internal tamper sensor that detects if the main electronics has been removed from the outer housing.

This is a laser sensor that detect if the distance to a hard surface below it has increased above 1 cm.

When intrusion is detected, this sends an alert message to the server via a text message.

This ensures that it operates in remote locations where an IP data connection may not be possible, providing the best chance of the message being delivered timely.

Once received by the server, the appropriate tamper status message is transmitted to the UK VMS Hub.

This method provides an earlier detection than system that rely upon an internal microswitch.




This sensor is already fitted to all MS44 devices.

This sensor can be activated on all installed MS44 devices remotely by Maritime Systems.


Time to implement

After approval from MMO the implementation can be undertaken immediately via the administrator portal at Maritime Systems.


Additional Tamper Security

If an engineer finds evidence of tamper, for example cut or missing tamper label, then they can report this to the server, and a tamper message will be sent to the UK VMS Hub.

4          Status Codes

GMV confirmed on the meeting that the only issues was the “Loss of GSM Reception” status message.

The “Loss of GSM reception” message cannot be sent when reception is lost, as there is no reception to send the message on.

GMV confirmed that the message was received correctly when GSM reception was restored.

GMV stated in the meeting that a “GSM Reception restored” message is required, but this is incorrect. It is not in the specification and can be inferred from the fact that data is slowing again.


There is no corrective action required here.


5          Blackout Performance

In the meeting GMV was not clear on the exact issue.

This has now been fixed.

In the server software code the number of satellites required to initiate a blackout status code was incorrectly set.

This has not been resolved.

Further testing by GMV will prove that this issue is fixed.


We do not need to interact with GMV.

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