Service 03
Unmeasured performance is performance on paper only
Bollard pull tests for tugs and speed, manoeuvring and machinery trials for vessels. We set up the test, run the measurement and coordinate class and owner attendance.
- Test types
- Bollard pull · Sea trials
- Attendance
- Class · Owner · Surveyor
- Output
- Measurement report
01Bollard pull test
What a tug can actually pull
Bollard pull is the static pulling force a tug can apply while stationary, and it is the tug’s commercial identity. Contracts, escort requirements and insurance assessments all rest on that figure.
For the test to stand up, the set-up must be right: sufficient water depth, current and wind within limits, towline length to standard, and a calibrated load cell. If any of these is missing, the measurement produces a number but not a certificate.
We organise the test site, the mooring arrangement, calibrated measurement equipment, recording and the attendance of the class surveyor. The output is a measurement report documented together with the date and the conditions.
02Test conditions
What makes a bollard pull test valid
A measurement taken without the following does not become a certificate.
- Water depth
- In shallow water propeller efficiency drops and the reading misrepresents reality; the site is chosen with adequate depth.
- Wind and current
- Wind and current must stay below limits, otherwise external forces contaminate the reading.
- Towline length
- The distance to the fixed point must be long enough to prevent propeller wash reflection.
- Calibrated measurement
- A load cell and recorder with valid calibration certificates are used.
- Duration and recording
- Recording is continuous over a set period; the steady-state value is taken, not an instantaneous peak.
- Surveyor attendance
- The certificate is issued under the attendance of a class society or independent surveyor.
03Sea trials
Verification after newbuilding and repair
A sea trial is the voyage where it is measured whether the vessel actually delivers the performance promised in the contract. It is run before newbuilding delivery and after major machinery repairs.
Scope varies with the job: speed trial, turning circle, zigzag manoeuvre, crash-stop, anchor trial, steering and machinery load tests, vibration and noise measurement.
Our role is to organise the voyage — area and time planning, an escort tug where required, the measurement team, attendance of class and owner representatives, and reporting of the result.
04Trial scope
Test items we run
Speed trial
Recording the speed–power relationship at several revolutions over a measured distance.
Turning circle
Measuring advance, transfer and tactical diameter at hard-over helm both ways.
Zigzag manoeuvre
Determining the vessel’s response time to helm and its directional stability.
Crash-stop
Measuring stopping distance and time from full ahead to full astern.
Anchor trial
Verifying windlass capacity and the times for paying out and heaving the cable.
Machinery load test
Running and monitoring main engine and generators at defined load steps.
A test is worth what its conditions record
The conditions matter as much as the figure itself: depth, weather, draft, displacement and date. When a dispute arises later, it is these records that speak.
Next step