Input Form
Formula Used
- Loose m3/h = (Bucket capacity × Fill factor) × (3600 / Cycle time)
- In-situ m3/h = Loose m3/h ÷ Swell factor
- Effective = In-situ × Operational efficiency × Utilization
- Totals: multiply by units, then by daily hours and monthly days.
- Loose solids m3/h ≈ Slurry flow × Solids concentration
- In-situ m3/h = Loose solids m3/h ÷ Swell factor
- Effective = In-situ × Operational efficiency × Utilization
- Optional mass: t/h = Effective in-situ m3/h × Density.
Note: These equations are planning-grade estimates. Calibrate inputs using measured cycles, flow logs, and downtime records.
How to Use This Calculator
- Select a dredging mode that matches your equipment.
- Enter measured field values where possible, not catalog values.
- Set efficiency for minor delays and operator performance.
- Set utilization for major downtime like moves and weather.
- Review hourly, daily, and monthly outputs for planning.
- Use download buttons to share results with your team.
Example Data Table
| Scenario | Mode | Key inputs | Effective in-situ (m3/h) | Effective in-situ (m3/day) |
|---|---|---|---|---|
| River maintenance | Mechanical | 2.0 m3 bucket, 95% fill, 45 s cycle, SF 1.25, Eff 80%, Util 85% | 91.733 | 917.330 (10 h/day) |
| Harbor silt removal | Hydraulic | 1200 m3/h slurry, 12% solids, SF 1.25, Eff 80%, Util 85% | 78.336 | 783.360 (10 h/day) |
| Two-unit operation | Mechanical | Same as river case, 2 units, 12 h/day | 183.466 | 2201.592 |
Example values are illustrative. Replace with site-specific measurements for best accuracy.
Practical Guide for Dredging Production Planning
1) Key production drivers
Production is controlled by a few measurable inputs: payload per cycle or solids per hour, cycle or flow stability, and the two adjustment factors used here—operational efficiency and utilization. For example, moving from 70% to 85% utilization increases effective output by 21.4%. Use site logs to separate short delays (efficiency) from major standby and moves (utilization) so assumptions remain defensible.
2) Mechanical dredging data inputs
In mechanical mode, the calculator multiplies bucket capacity by fill factor, then divides by cycle time. A 2.0 m3 bucket at 95% fill and a 45-second cycle yields about 152 m3/h loose before downtime. If swing distance grows or material becomes stiff, cycle time may rise to 60–90 seconds, reducing output by 25–50%. Track at least 20 cycles to average a realistic time.
3) Hydraulic dredging data inputs
In hydraulic mode, production is estimated from slurry flow and solids concentration. A 1200 m3/h slurry stream at 12% solids produces roughly 144 m3/h loose solids before downtime. Concentration often varies with cutter settings and pipeline losses; even a change from 10% to 14% solids shifts output by 40%. Prefer measured flowmeter data and periodic density sampling for calibration.
4) Loose versus in-situ volumes
Contract quantities are frequently specified as in-situ (bank) volume, while dredges handle loosened material. The swell factor converts between them: bank = loose ÷ swell. A swell factor of 1.25 means 100 m3 loose equals 80 m3 in-situ. Use a project-specific factor based on sediment type and placement method, and apply the same basis consistently in reporting.
5) Turning results into schedules and costs
Once effective in-situ m3/h is calculated, multiply by planned hours to obtain daily and monthly targets. Use the “units” field for parallel dredges and keep hours realistic for tide windows and disposal restrictions. If density is known, the tonnes per hour output supports trucking or barge capacity checks, helping align plant, haul, and disposal to avoid bottlenecks.
FAQs
1) What is the difference between operational efficiency and utilization?
Efficiency covers small delays during active work. Utilization covers major downtime such as weather, moves, fueling, and standby. Multiply both to get an effective production rate.
2) Which volume should I report for payment: loose or in-situ?
Use the contract basis. Many specifications pay on in-situ (bank) quantities, while dredge handling is loose. Apply swell consistently and document the selected factor.
3) How do I estimate cycle time for mechanical dredging?
Time a representative set of cycles including dig, swing, dump, and return. Average at least 20 cycles. Update the value when swing distance, depth, or disposal method changes.
4) What solids concentration should I use for hydraulic dredging?
Start with measured values from density sampling or plant instrumentation. If unknown, run a short trial and back-calculate concentration from delivered solids, then adjust for typical operating conditions.
5) Why does production drop sharply when utilization decreases?
Utilization scales the whole shift. A change from 85% to 65% removes 20% of productive time, so hourly, daily, and monthly totals all decline proportionally.
6) Can this calculator handle multiple dredges working together?
Yes. Enter the number of units to scale effective production. Use the same assumptions only if the dredges and haul/disposal conditions are comparable.
7) How should I choose a swell factor?
Use a project-specific factor based on sediment type and placement method. If you lack lab data, start with a conservative value and refine it using survey quantities and placement measurements.