A working toolkit for marine engineers and procurement teams — interactive calculators for rope weight, sling working loads, elongation and material selection, backed by a reference library you can return to on every project.
Quick first-pass figures for specification and planning. Switch between tools below.
Enter parameters to estimate linear density, total weight and reel size.
Enter a breaking load and configuration to find the safe working load.
Enter parameters to estimate elongation under load.
The fibre families behind the Solaris Marine range, with the trade-offs that decide which one fits your application.
| Fibre | Density (kg/m³) | Strength / wt | Stretch @ break | UV life | Abrasion | Heat | In seawater | Typical use |
|---|---|---|---|---|---|---|---|---|
| HMPE | 970 | ★★★★★ | ~3.5 % | Good | Very good | Low | Floats | High-performance mooring, towing, slings |
| Aramid | 1440 | ★★★★ | ~3.6 % | Fair* | Good | Excellent | Sinks | Low-stretch, high-temperature lines |
| Polyester | 1380 | ★★★ | ~13 % | Excellent | Very good | Good | Sinks | Permanent mooring, general marine |
| Nylon | 1140 | ★★★ | ~25 % | Good | Very good | Good | Sinks | Shock / snap loads, tug & berthing |
| Polypropylene | 910 | ★★ | ~18 % | Fair | Fair | Low | Floats | General purpose, aquaculture, fishing |
| Steel core | 7850 | ★★★★ | ~2 % | Excellent | Excellent | Excellent | Sinks | Maximum cut / abrasion resistance |
*Aramid requires a protective jacket for UV and abrasion service. Wet strength loss applies mainly to nylon (~10–15 %). Ratings are relative within marine rope applications.
How the fibre is laid or braided changes strength, handling, splicing and abrasion behaviour as much as the fibre itself.
Indicative minimum design factors by application. Always defer to the governing class society, OCIMF MEG4 or LEEA code for the actual installation.
| Application | Typical design factor | Governing reference | Notes |
|---|---|---|---|
| Permanent synthetic mooring | 5:1 – 6:1 | OCIMF MEG4 · class society | Line Design Break Force assessed against dynamic analysis |
| Tug / towing line | 4:1 – 5:1 | Class society | Account for shock and snap-back zones |
| Anchor handling | 4:1 | Operator procedure | High dynamic duty — inspect frequently |
| General lifting sling (fibre) | 7:1 | EN 1492 · LEEA | WLL marked on every sling |
| Salvage / emergency tow | 7:1 | Engineered case-by-case | Single-use rating may apply |
| Critical / personnel | 10:1 | Regulatory | Never improvise — certified equipment only |
Retire a rope when any single criterion is met — damage is cumulative and often hidden inside the construction. When in doubt, take it out of service.
Widespread fuzzing or broken outer filaments reducing the effective cross-section beyond the manufacturer's threshold.
Any cut strand, snagged loop or strand displacement disrupts even load sharing across the rope.
Melted, fused or glazed fibres from friction or external heat — strength loss is severe and irreversible.
Powdering or grit between strands when flexed — a key indicator for fibre ropes that look sound externally.
Significant discolouration, surface chalking or stiffening from prolonged sunlight exposure.
Contact with acids, alkalis or solvents — some attack specific fibres invisibly. Quarantine and assess.
Any overload, sudden snatch or near-failure event warrants inspection and likely retirement of the line.
End-of-life per the rope-management plan — track install date, cycles and load history per line.