Deckcheck

Before you start

Deckcheck is an educational visualisation, not a safety tool.

Although the app uses real physics formulas to simulate a fall, the physics is simplified in places and has not been validated against measured falls. Forces and distances are estimates.

You can see and estimate how slack affects a fall, but do not use it to decide how much slack to carry, where to clip or whether a fall is survivable.

Climbing is dangerous: rely on training, manufacturer instructions and qualified instruction. Use at your own risk.

How to use

On screen

⤢
FITshows the whole system
⇅
SLACK 0pulls all slack out of the rope
▼↺
DROP · RESETlet the weight fall · put it back where it fell from

Hold an empty spot

a new bolt appears · keep holding to drag it into place

+QD
+QDpick a quickdraw for the bolt
SML
S · M · Lshort · dogbone · 60 cm sling · tap again to remove
✕delete the bolt
Hold the rope, drag it onto the quickdrawthe rope clips in

Tap a clipped bolt

a bolt the rope already runs through

MQD
QDchange the quickdraw size
−QD
−QDunclip: the rope comes out, the bolt stays
∞knot
knotholds the rope here up to 1.2 kN, then slips and unties · teal = on
rip
ripthe bolt fails at 1 kN in the fall · amber = armed
✕delete the bolt

Tap the weight

+−
+ / −5 kg heavier · lighter

Tap the anchor

+QD
QDa quickdraw at the anchor

Gestures

Hold the weight, drag itclimb · the rope feeds out
Hold a bolt, drag itmove it
Drag · pinchmove the view · zoom
Double-tap, then dragzoom with one finger
Tap an empty spotcloses a menu

Settings

▲ settings
SETTINGSopens the panel at the bottom
dynsemi
Rope typedynamic or semi-static
−+
Rope length5 m steps · the unused rope hangs as dead rope
disclaimer
Disclaimerread it again
privacy
Privacynothing you do leaves your device
?
?this help

Numbers

MIN. GAPclosest the weight came to the ground · GROUND FALL — it hit
5.1mΔ2.40.0kN0.3kN
Next to each pointheight · Δ above the point below · force now · peak

Privacy Policy

Last updated: 2026-10-21

Deckcheck is a fall simulator for lead rope solo climbing. It does not collect, store or share personal data.

What the app does not do

No accounts and no sign-in.
No analytics, advertising or tracking of any kind.
Nothing you set in the simulation — bolts, slack, weight, rope — leaves your device. The physics runs entirely on your device.

What stays on your device

To work without a connection, the app keeps a copy of its own files (the page, fonts and icons) in your device's browser storage.
It also remembers, on your device only, that you accepted the disclaimer.
Clearing the app's storage or uninstalling the app removes both.

Hosting

The app is delivered from a web server. Like any web host, the hosting provider may record standard technical data, such as IP address and time of request, in server logs to deliver the site and protect it from abuse. The developer does not use these logs to identify or follow users.

Children

The app does not collect personal data from anyone, including children.

Changes

If this policy changes, the new version will be published here with a new date.

Contact

Questions about this policy: valna@tuta.io