Files and offline use

MakeSail keeps your design in the browser while you work. To keep it for a later session, save a JSON file to your own device. There is no autosave, server-side design library, or cloud recovery copy.

Save a design

Choose File > Save or press Cmd/Ctrl+S.

• In Chrome, Edge, and other browsers that support the system file picker, the first Save asks for a location. Later saves in the same session overwrite that file. File > Save As always asks for a new location.
• In Firefox and Safari, Save downloads a new file. Save As asks for a filename and then downloads it.
• Cancelling the picker or filename prompt leaves the design open and unchanged.

The default name combines the sail type with the local date and time, such as gennaker-20260730-143012.json. You can rename the file without changing its contents.

The filename in the app gains a • when the current design has changes that have not been saved. A successful Save removes that mark.

Keep the downloaded file

The JSON file is the recoverable copy of your design. Closing the tab without one can permanently lose the work.

What the file keeps

A saved file keeps the settings that define the design:

• sail type and dimensions;
• edge shape, section profiles, twist, and mould controls;
• Automatic / Individual profile mode and its saved recipe;
• cloth and construction settings;
• panel layout;
• panel colour choices; and
• the boat file, when the design started from a local boat file.

Reopening keeps the saved profile mode and shape. Files without a profile mode open in Individual; their profiles are not regenerated. Returning to Automatic is a separate confirmed edit, described in Profiles and fullness.

Generated flat panels are not stored in the file. Neither are the current camera, workspace, visible layers, account session, or Apply postprocess choice. Generate panels again after opening if you want to view or export them.

Boat files are separate from sail designs

A boat file is the portable hull and rig file produced by Hull Lab and read by the sail designer. It is not a saved sail design: a saved sail design holds a complete sail, while a boat file holds a hull and rig. A design that started from a boat file also carries its own copy of that boat file inside it.

Open a boat file with File > New, not File > Open — in Step 1 choose + Local boat file... (or Open local boat file...), then pick a sail type. To hand the same file back out of an existing design, use File > Extract Boat..., which downloads it with a name ending in .hull.json.

Hull Lab's File > Save and Extract Boat both write .hull.json files in the same boat-file format. See Hull Lab and boat files for the full workflow.

Open a saved design

1. Save the design currently on screen

   File > Open does not ask before replacing an unsaved design. Save the current work first if you may need it again.

2. Choose File > Open (Cmd/Ctrl+O)

   Select a JSON file previously created by MakeSail. A successful open restores the saved shape, cloth, construction, layout, and colours, then recalculates the preview and seam overlay.

3. Generate panels again when needed

   Opening clears any earlier generated panel set and its warnings. Choose Panels > Generate Panels before returning to the panel viewer or a panel-based export.

After Open, the next Save asks for a destination even in a browser that can overwrite files. Opening a file does not give the app permission to write back to that same file.

Supported sail types

Files for all nine sail types can be saved and reopened:

• Gennaker
• Code 0
• Genoa 135%
• Working jib
• High-aspect jib
• Symmetric spinnaker
• Mainsail
• Storm jib
• Storm trisail

The loader also updates several older MakeSail file formats automatically, including former chord, rig, twist, colour, layout, and headsail-tack data. If a file is not a recognised MakeSail file, the app shows a load error: banner instead of partly loading it. Do not edit the JSON to work around that message; return to a known copy or create a new design.

Protect unsaved work

The app handles replacement actions differently:

Action	Current warning
File > New while the design is changed	An in-app confirmation asks before starting over.
Reloading or closing a changed tab	The browser can show its native leave-page warning.
File > Open while the design is changed	No confirmation; the selected file replaces the design immediately.

Save before any of these actions. If the tab has already closed and no saved file exists, the app cannot restore the design.

What works without the backend

Once the app page has already loaded, these design-time actions run in the browser:

• create, shape, and inspect a sail;
• use the 3-D, 2-D, and Heatmaps workspaces;
• preview all five panel layouts and their seams;
• edit profiles and Tri-radial colours;
• save and open local design files;
• build, trace, and save a hull in Hull Lab; and
• load and trace an already-saved Cloth Layout DXF in Projector Workspace.

These actions need a connection to the MakeSail backend:

• Generate Panels; and
• all five downloadable DXF and PDF exports.

Creating the Cloth Layout DXF for a projector job therefore requires the backend first. Once that file is saved, Projector Workspace reads it locally without the current design or an active account session.

This is not an installed offline app: loading the site for the first time, or reloading it after browser data has been cleared, can still require a network connection. Sign-in is covered separately in Sign-in and account.

Start hereMake a first sail → Follow one design from File > New through save and export. Start from drawingsBuild a hull in Hull Lab → Turn a lines drawing into a boat file, then open it with File > New. Help and referenceTroubleshooting → Recover from a save, load, generation, or export failure.