Snubline

Explore rigging physics with an educational model.

Snubline uses assumed inputs to illustrate equations and compare numerical values. It has no independent professional validation or complete rope calibration dataset. It is not a professional planning or load-safety assessment tool. Do not use its results to select equipment, determine actual loads, plan a cut, or decide whether an operation may proceed. Obtain qualified on-site assessment independently of the app.

THE EDUCATIONAL MODEL
- Compare snubbed and constant-slip let-run assumptions using a closed-form spring-mass equation.
- Inspect peak tension, dynamic load factor, stretch, block force and device force, with equation details.
- The rope conversion factor 0.075 and example moduli are provisional teaching values.
- The 75%-125% display range is illustrative, not a validated error bound or confidence interval. Actual loads may fall outside it.
- Fall factors above 2 are limited to 2, with a visible warning; the result no longer represents the full entered drop.

NUMERICAL FORCE-VERSUS-RATING COMPARISONS
Enter your own tag ratings and design factors. Within WLL, Approaching WLL, Exceeds WLL and Exceeds MBS describe numerical comparisons of model values only. They do not approve equipment or operations.

EXAMPLES AND DOCUMENTS
Estimate log weights from idealized geometry and species density, with estimate labels carried into comparisons. Save scenarios, gear records and jobs. Compare scenarios and share educational comparison PDFs or images. Existing frozen snapshots remain stored; documents rendered by this version carry the current educational restriction.

TRANSPARENCY
The free model page explains equations, provisional calibration, formula-test limitations and omitted effects including swing, tree flex, rope heating, friction variation and fatigue. Climbing, life support and crane operations are outside the model.

YOUR DATA
Records remain on your device. No account or cloud sync. If saved records cannot be opened, recording is paused and existing database and attachment files are kept.

FREE
Both model modes, equation details, the weight estimator, the model page, three Gear Locker items and one job.

PRO
Unlimited Gear Locker items and jobs, what-if comparisons, PDFs and share cards, custom rope profiles and widgets. Pro does not change model validity or calculation correctness.

Choose a one-time Lifetime purchase or annual subscription. Existing monthly subscribers retain access while their Apple-verified entitlement is active. Any trial applies only when Apple confirms eligibility; the purchase screen shows the actual price and offer. Subscriptions renew unless cancelled in Apple subscription settings before renewal.

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Terms of Service: https://app-legal-pages.vercel.app/snubline/terms