trailwright.
A real tarp and hammock between tall trees, catching the evening light in Rebild Bakker, Denmark
A FIELD NOTEBOOK THAT DOES THE MATH

Test your
setup.
Then take it
outside.

Pitch a tarp. Time the route. Weigh the pack.
Twelve tools and 37 worked guides to use before you go,
and keep when the signal ends.

Open shelter studio ↗Save the field pack ↓

No account. Your calculations stay with you.

REBILD BAKKER
DENMARK / REAL PHOTOGRAPH
NICOLAS WELDINGH / UNSPLASH
THE WORKBENCH / 01—12

GET
YOUR
BEARINGS.

One question at a time.
Change the input. Inspect the model.
See what changes the answer.

Deep channels in weathered tree barkA real tarp and hammock among tall woodland treesMEASURE. ADJUST. REPEAT.
  1. 01

    Shelter studio

    Pitch height, usable floor and line lengths.

  2. 02

    Loaded miles

    Pack mass, walking speed and uphill grade.

  3. 03

    Knot bench

    Step diagrams and material tradeoffs.

  4. 04

    Sun & daylight

    Sun bearing, sunset and civil twilight.

  5. 05

    Water decisions

    Germs, cloudy water and contamination.

  6. 06

    Power budget

    Device draw, batteries and solar scenarios.

  7. 07

    Trail time

    Naismith time, descent corrections and finish time.

  8. 08

    Map slope

    Contours and map distance into grade and pace.

  9. 09

    Feels like

    Wind chill and heat index, with risk bands.

  10. 10

    Altitude

    Air pressure, boiling point and summit temperature.

  11. 11

    Pack ledger

    Base weight, consumables, total and skin-out.

  12. 12

    Food carry

    Daily energy and food density into carried weight.

All tools, grouped by job ↗
Fog tracing the steep wooded slopes of the Racha mountains in Georgia
LEAVE RECEPTION PREPARED

NO SIGNAL.
KEEP PLANNING.

EVERY TOOL. EVERY DIAGRAM. ON THIS DEVICE.

Save the full field pack before you go. Your scenarios stay in this browser. Reconnect to check for a newer edition.

Download the free pack

Test it in airplane mode. Carry independent maps, training and emergency communications.

REAL LANDSCAPE / MAKSIM SAMUILIONAK
THE FIELD LIBRARY

THE DETAIL
CHANGES EVERYTHING.

Read all field notes ↗
A woodland tarp shelter photographed by Nicolas Weldingh
GEOMETRY / FIELD COMPARISON

One more metre.
How much more room?

Same ridge height. Longer tarp.
See exactly what changes.

A close study of rough, fibrous tree bark
CORDAGE / MATERIAL BEHAVIOUR

Strength is only
part of the story.

Stretch, grip and the termination.
Different fibres, different limits.

Layers of fog moving between wooded mountain slopes
WATER / TREATMENT DECISIONS

Clear water.
Unanswered questions.

Start with the source hazard.
Then compare treatment methods.

FIELD GUIDES / 37 WORKED ARTICLES

READ THE
WORKINGS.

Each guide takes one question, works it through with the formula and a real example, cites its sources and says where the model stops. Then it hands you the tool with the numbers filled in.

Browse all guides ↗Start with turnaround time

  1. Shelter & camp5 guides

  2. Pace, load & food5 guides

  3. Maps, slope & daylight6 guides

  4. Water treatment5 guides

  5. Weather & altitude5 guides

  6. Power & batteries4 guides

  7. Knots & cord4 guides

  8. Trip planning3 guides

THE ASSUMPTIONS

KNOW WHAT
CHANGES
THE ANSWER.

Check the assumptions behind each estimate before using it in your plan.

Read the method