Inputs
Formula used
Cycle time (seconds) = Dig/Fill + Loaded Travel + Dump/Discharge + Empty Return + Positioning + Delays.
Raw cycles per hour = 3600 ÷ Cycle time.
Effective cycles per hour = Raw cycles per hour × (Efficiency ÷ 100).
Loose volume per cycle (m³) = Bucket volume × Fill factor.
Loose production (m³/h) = Effective cycles per hour × Loose volume per cycle.
Bank production (m³/h) = Loose production ÷ Swell factor.
How to use this calculator
- Choose travel input mode: times, or distance and speed.
- Enter per-cycle durations for digging, dumping, positioning, and delays.
- Set efficiency to reflect real-world downtime and variability.
- Enter bucket (or cut) volume, fill factor, and swell factor.
- Click Calculate to view cycle time and production above.
- Download CSV or PDF to attach to plans and estimates.
Example data table
| Scenario | Cycle (s) | Efficiency | Bucket (m³) | Bank m³/h | Bank m³/shift |
|---|---|---|---|---|---|
| Baseline | 79 | 85% | 1.50 | 43.58 | 348.61 |
| Longer travel | 101 | 82% | 1.50 | 32.88 | 263.05 |
| Better fill | 79 | 85% | 1.50 | 50.84 | 406.71 |
Cycle time drivers in dredging operations
The cycle time is the sum of digging/filling, travel to disposal, discharge, return travel, positioning, and short delays. On most sites, one component dominates. If loaded travel is the biggest share, shorten the route, improve traffic control, or move the discharge point. If digging dominates, review cutter settings, bucket size, and material conditioning.
Travel path and swing efficiency benchmarks
Travel time can be entered directly or derived from distance and average speed. Use measured average speeds, not peak values. For example, 45 m at 2.0 m/s is 22.5 s. A 10% reduction in travel time often yields a similar increase in cycles per hour when other steps stay constant.
Production conversion: loose vs bank volumes
Per-cycle loose volume equals bucket volume multiplied by fill factor. Bank production divides loose production by swell factor to reflect in-situ volume. Example: bucket 1.50 m³, fill factor 0.90 gives 1.35 m³ loose per cycle. With swell factor 1.20, bank volume is 1.35 ÷ 1.20 = 1.125 m³ per cycle.
| Example input | Value | Example output | Value |
|---|---|---|---|
| Dig / Fill (s) | 25 | Cycle time (s) | 79 |
| Loaded travel (s) | 18 | Effective cycles/hour | 38.73 |
| Dump / discharge (s) | 10 | Bank production (m³/h) | 43.58 |
| Empty return (s) | 15 | Bank production (m³/shift) | 348.61 |
Using cycle logs for planning and control
Log at least 30–50 cycles and compute average times for each component. Compare the measured breakdown to the calculator output to spot drift. If delays grow during the shift, adjust efficiency or add a separate delay allowance. Updating inputs weekly keeps forecasts aligned with reality.
Sensitivity checks for bids and schedules
Run “best, expected, worst” cases by varying efficiency, travel, and fill factor. Small changes compound: a 5 s reduction from a 79 s cycle increases raw cycles/hour from 45.57 to 48.00. For schedule buffers, use bank m³/h because it matches pay quantities and design volumes. Also review shift hours and planned downtime so daily targets remain achievable in the field. One consistent input set supports better crew planning, reporting, and cost control.
FAQs
1) What counts as one dredging cycle?
A single cycle includes digging or cutting, moving or swinging to discharge, dumping, returning to the cut, repositioning, and typical short delays. Enter each step as an average per cycle.
2) Should I use travel time mode or distance mode?
Use time mode if you already measure cycle components with a stopwatch or telemetry. Use distance mode when travel varies by route length and you can estimate average speeds reliably.
3) How do I choose job efficiency?
Start from observed productive time during a shift. Include routine interruptions such as brief waits, minor maintenance, and operator breaks. Many projects land between 70% and 90%, depending on logistics and material.
4) What is fill factor and why does it matter?
Fill factor represents how full the bucket or intake is versus its rated capacity. Sticky clays may reduce it, while well-graded sands can improve it. Production changes linearly with this factor.
5) Why convert loose volume to bank volume?
Pay quantities and design volumes are usually in-situ (bank) terms, while excavated material expands. Swell factor converts loose volume back to bank volume so schedule and payment comparisons stay consistent.
6) Can I apply this to different dredging methods?
Yes, as long as you can define repeatable cycle components. Replace “bucket” with average cut volume per cycle and adapt travel to pipeline transfer, barge loading, or swing time. Keep units consistent across inputs.
7) What are quick ways to improve production?
Target the largest time share first: shorten loaded travel, reduce discharge congestion, and standardize positioning. Verify fill factor with field checks, then tune efficiency with better shift planning and proactive maintenance.