KONGSBERG MRU-M-MB3 – Marine Motion Reference Unit with MB3 Bracket for Reliable Roll/Pitch/Heave Data

The KONGSBERG MRU-M-MB3 is a marine‑rated Motion Reference Unit configured with the MB3 mounting bracket, built for precise roll, pitch and heave measurements on vessels and offshore platforms. From my experience, this is the kind of sensor you fit once and depend on for years—especially when dynamic positioning, heave‑compensated cranes, multibeam sonars, or helideck monitoring systems need stable, low‑latency motion data. You might notice that Kongsberg’s MRU line typically provides high update rates and robust filtering, so integration into existing navigation or survey stacks tends to be straightforward.

Order Placement Process and Guarantees

Key Features

• Marine‑grade MRU sensing – Measures roll, pitch, and heave with stable output for DP, survey and crane ops.
• MB3 mounting bracket included – Speeds up bulkhead or deck installation and helps with axis alignment.
• High update rates – Typically supports fast data output (up to high tens or 100+ Hz) for low‑latency control loops.
• Real‑time and delayed heave – Real‑time output for control, delayed (filtered) heave for improved accuracy in many cases.
• Flexible I/O – Ethernet and serial interfaces with common marine protocols (e.g., NMEA‑style ASCII and binary formats).
• Robust filtering – Motion filters tuned for vessel dynamics; seems to be especially effective in swell and long‑period seas.
• Integration‑friendly – Works well alongside multibeam sonars, attitude heading reference systems, and DP controllers.

Technical Specifications

Where it fits best

• Dynamic positioning input on OSVs, PSVs and research vessels
• Heave‑compensated offshore cranes and moonpool handling
• Multibeam echo sounder stabilization and patch‑test repeatability
• Helideck motion monitoring and gangway control (real‑time heave)
• USV/ASV payload stabilization where low latency is critical

A chief engineer on a North Sea PSV told us the MRU “settled fast after turns and gave steadier heave numbers for the crane team,” which matches what we typically see when the filters are properly tuned.

Related or Supporting Products

• KONGSBERG MRU 5+ – Higher‑grade MRU with improved roll/pitch accuracy and advanced heave options.
• KONGSBERG MRU H – Heave‑optimized variant favored for crane and wave‑compensation tasks.
• KONGSBERG MRU E – Cost‑effective unit for general survey and platform monitoring where moderate accuracy is fine.
• KONGSBERG Seapath series – GNSS/INS systems that can complement the MRU for navigation‑grade position and attitude.
• MB3 Mounting Bracket (spare) – Replacement/extra bracket identical to the one bundled with MRU‑M‑MB3 for quick swaps.

If you’re swapping an older MRU on a multibeam, the MRU‑M‑MB3 usually drops in with minimal software changes—protocols tend to line up, and output rates can be matched to your sonar ping schedule.

Installation & Maintenance

• Mounting – Fix the MB3 bracket to a rigid, low‑vibration surface near the vessel’s roll/pitch axes. Align the sensor arrows with ship axes. Avoid flexible decks or thin panels.
• Cabinet & environment – For cabinet installs, allow cable bend radius and strain relief. The housing is marine‑sealed; still, keeping connectors dry and looped for drip protection helps in most cases.
• Wiring – Use shielded twisted pairs for serial lines; bond shields at a single ground point to reduce loops. For Ethernet, use marine‑rated Cat cable and proper glands.
• Setup – Configure output rates and formats to match your control/survey system. Heave filters may require a brief learning period to reach peak stability.
• Safety – De‑energize before connecting/disconnecting. Verify polarity and supply range to prevent damage.
• Routine maintenance – Check fasteners and alignment marks quarterly. Clean connectors, inspect seals, and back up configuration. Firmware updates (when available) typically improve filtering and timing.
• Calibration – Factory‑calibrated; field calibration is rarely needed. If the MRU is relocated, run a quick verification and re‑align axes in software.

Quality & Certifications

• CE compliant and RoHS conformant for marine electronics (typical for the MRU series)
• Marine type approvals (DNV, ABS, LR) are commonly available on KONGSBERG MRU variants; we can share the exact certificate set for MRU‑M‑MB3 on request
• Manufacturer’s standard warranty is typically 12 months; our supply includes a 365‑day warranty