AHTS Fuel Monitoring: Operation Modes and Bunker Checks Offshore

MANTRAZ is an AHTS fuel monitoring system for operators of anchor handling tug supply vessels who want to know what each engine burns in each kind of work. Main engine fuel is measured by flowmeters on the supply and return lines, engine time is split into operation modes you define, and the data keeps flowing from the offshore field back to the office.

Offshore work, uneven engine load

An AHTS supports offshore operations: towing, handling anchors, carrying supplies and standing by. The engine load swings widely between these jobs, from long periods waiting on location to hard pulls during towing and anchor work. A daily fuel total averages all of that into one figure that says little about where the fuel actually went.

Distance adds its own problems. Far from the coast, data is harder to get back to shore, and an engine problem can go unnoticed until someone reads a logbook.

AHTS fuel monitoring, per engine

For offshore vessel fuel monitoring, MANTRAZ shows RPM, speed and fuel consumption for each engine side by side, with fuel density and temperature, running hours, exhaust temperature and power meter readings where one is installed. Auxiliary engines are usually estimated from running hours, and reports keep measured and estimated fuel apart.

Splitting the day by operation mode

Because an AHTS changes job so often, running hours alone say little. With operation mode analysis you name RPM bands for each engine, such as idle, maneuver, cruise and full, and MANTRAZ classifies every minute the engine runs. You see how long each engine spent in each mode, what share of its running time that was, and the litres each mode used, based on the consumption rate you set. The office and the crew get hard numbers, such as time spent at full RPM.

Bunker verification

Every bunker should end with a figure everyone accepts. After each bunkering, the bunkering log sets the target against the MANTRAZ flowmeter total and the tank sounding before and after, with the discrepancy in KL and %. Corrections are recorded as adjustments with a reason, such as a pipe leak, spillage, meter calibration or a supplier dispute, along with who made them and when. Any dispute with the supplier starts from data.

Staying connected offshore

Near the coast, the onboard gateway sends full data over cellular. Out at sea, Starlink on board carries the same full data. A vessel with neither can report through the app's satellite mode, which brings in position, RPM and auxiliary engine data only and counts the vessel online if its GPS arrived within 6 hours instead of 10 minutes. You know what data to expect from a vessel on each link.

Alerts while there is time to act

Rules on onboard sensor readings, such as exhaust temperature or RPM above a limit, raise alerts with Critical, Warning or Info severity, and so does a device that stops sending data. Your team gets them in the app and by email, and the event log and alert history record when each alert triggered, when it cleared and how long it lasted.

Already running on AHTS vessels

MANTRAZ is already installed on AHTS vessels, as well as on tugboats, LCT and MV vessels. The AHTS is one example, not a limit: the same system suits other offshore and non-offshore vessels too.

See it with your own fleet

To see how engine time is split on your own vessels, contact the team for a demo.