ywSynch is a Windows program designed to allow a yWriter5 project to be edited on Android (or other) devices. It can be freely downloaded and distributed. (It should also work with on Linux with Mono 1.2.5 or later, but this has not been tested.)
yWriter stores the structure of your book in a .yw5 file, which for the technically minded is a straightforward xml file. The text of the individual scenes is stored in a set of numbered RTF files. This allows you to change the book structure in yWriter, moving scenes around, renaming them etc. but makes it difficult to identify which RTF file contains which scene if you were to copy them onto a device that can't run yWriter.
ywSynch allows you to make a copy of your yWriter project that reflects the structure of your book, with numbered and named folders for each chapter, and numbered and named document files for each scene. They are numbered so that they will appear in order within the file manager on the device.
It also allows you to specify a document format for the files that it copies to the device. Currently .doc, .docx and .odt formats are supported, as well as .rtf (in case you have a device that can edit rtf files).
You can then edit scenes on your device, and run ywSynch again to copy the edited versions back to your PC. If you instead, or also, carry on editing on the PC, ywSynch will allow you to update the copies. Of course, if you edit the same scene at both ends ywSynch won't be able to work out exactly what you wanted, but can a make separate copy on the PC of the document from the device, which you can use to edit the main document later.
If you are using an editor on your device that cannot edit and save rtf files (eg Docs to Go) ywSynch needs LibreOffice's Word Processing application (swriter.exe) installed on the PC to carry out document format conversions. LibreOffice is a free (by which I mean both open source and no cost) Office Suite. After Sun was bought by Oracle the developers of OpenOffice left the company and set up The Document Foundation to carry on OpenOffice development. If you are currently using OpenOffice you should seriously consider changing to LibreOffice in order to benefit from future developments.
On the other hand, if your editor can edit and save rtf files (eg OfficeSuite Pro on Android) you don't need LibreOffice on the PC at all.
ywSynch has been developed primarily to work with an Asus Transformer, but will also work with some Android phones. It should also be possible to use it with an iPad, but this has not been tested.
Please note that Simon Haynes and Spacejock Software (the developer of yWriter5) do not provide any support for ywSynch. For details of support for ywSynch see the Support page.