The project
Keeping every Moth competitive by sharing knowledge
Why Opensource Moth?
The International Moth is one of the most exciting boats on the water – and one of the fastest-moving development classes. New foils, wands, gantries and rig tweaks appear every season. That is what makes the class great, but it also means that a boat that won races a few years ago can quickly feel outdated, and that the cost of keeping up pushes sailors out of the fleet.
An old Moth does not have to be a bad Moth. Most of the speed gained in recent years comes from components – control systems, foils, rudder assemblies, trim systems – that can be upgraded on an existing hull. With the right drawings, a bit of workshop time and some help from the community, a second-hand Mach 2, Exocet or Bieker can stay competitive for many more seasons.
Opensource Moth is a place where sailors share exactly that knowledge: designs, build instructions, CAD files, material lists and honest cost estimates. Every part is published by a sailor, reviewed by an administrator, and open to feedback from everyone who builds it.
Extend boat life
Upgrade instead of replace. Every hull kept on the water is one more boat on the start line.
Lower the entry cost
Affordable, proven upgrades make the class accessible to young and new sailors.
Share, don't hide
Knowledge that is shared gets improved. Feedback from builders makes every design better.
Extending the life of Moths can only result in a wider approval of the class: bigger fleets at club level, more second-hand boats that are worth buying, and more sailors discovering foiling.
Licence: what you may do with the files
All designs, drawings, CAD files and build instructions on this website are published under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licence, unless a part page says otherwise.
We chose this licence because it matches the spirit of the project best. Open-hardware licences such as the CERN Open Hardware Licence or the TAPR licence explicitly allow commercial production, which is not what we want. The CC BY-NC-SA licence is widely known, legally well tested and forbids commercial use.
✔ You may
- Download the files and build the part for your own boat.
- Build a part for a friend or clubmate, asking at most the cost of the materials.
- Modify and improve the design – and share your version back here under the same licence.
- Ask the creator to build one for you as a favour between sailors.
✘ You may not
- Sell parts made from these files for profit, or offer them in a shop or series production.
- Sell or re-publish the files themselves for money.
- Remove the name of the original creator.
- Re-share a modified version under a more restrictive licence.
Opensource Moth community guidelines
On top of the licence, all members agree to these fair-use guidelines, which explain how we interpret "non-commercial" on this site:
- Small quantities only. Build parts for yourself and your friends – as a guideline, no more than a handful of units of any design per year.
- No profit. Charging for materials and consumables is fine; charging for labour or margin is not.
- Attribution. Mention the creator and a link to the part page when you show or share your build.
- Give back. Post feedback, photos and improvements on the part page so everyone benefits.
- Commercial interest? Want to produce a design in series? Contact the creator – they own the design and can grant you a separate commercial licence.
Sailing and building are at your own risk. Designs are shared as-is, without warranty; check class rules and make sure every part you build is safe. This page is an explanation, not legal advice – the full licence text on the Creative Commons website is binding.
Get involved
Built something clever for your Moth? Share it. Found a mistake or want to help run the project? Get in touch.