4D Nav’s Pipelay Exit Monitoring System (PEMS) provides offshore pipe lay operators with an exceptional tool for visualizing and logging the position of the pipe relative to an ideal exit.

Based on the NavView suite of positioning and navigation software, PEMS incorporates a laser measurement system to continuously monitor and record changes to the pipe center position as it exits the lay vessel tensioner or hold-off module (HOM).

Installation requirements are easily met on most vessels. The laser requires only 24VDC and a single CAT 5 or 7 data cable to make it operational. The processing computer is fitted to the back of the display monitor, making the whole package compact enough to fit wherever the monitor can be installed. Tension output from most SCADA systems is easily interfaced, if desired.

The PEMS processing starts by inputting the raw laser data into a shape detection algorithm that computes the center and radius of the pipe. The resulting output is routed to the display and data logging modules. The operator is presented with a simple bull’s-eye view of the pipe deviation from center, allowing informed payout or vessel speed decisions to be made.

A two-minute calibration procedure executed at the beginning of operations establishes a reference center. From that point, millimeter pipe deviations from the reference can be measured.

4D Nav - PEMS


  • Laser tracking continuously monitors pipe exit angle
  • Easily-interpreted bull’s-eye view makes even small deviations of the pipe from center clear to operators
  • Warning zones may be configured at fixed distances from the center, or be dynamically driven by real-time tension measurements
  • May be configured to use a fixed pipe diameter, or to dynamically calculate pipe diameter from the laser data
  • All tracking data is time-tagged and saved at a 1-second interval
  • A visual query tool allows data from any time period to be retrieved and exported as a CSV file
  • Meets essential requirements of DNV-OS-F101 for pipe exit monitoring and logging

Click here to view the PEMS datasheet.