If you unpack a Mac archive on a
Windows system, and any of the files in that archive had a resource fork, the
Windows version of Stuffit Expander simply discards the resource part of the file
and preserves the data part. For many files, such as JPEG images or most word
processing documents, there is no harm in this. For other types of files, much
of the important information was in the resource fork, and the file will be
useless on the PC (and useless when transferred to the Mac without its resource
fork). This is especially true of Mac applications, including .sea files.

This is especially true of Mac applications, including .sea files.

http://www.emaculation.com/doku.php/kegs

I encountered someone else having trouble extracting the GS/OS disk images, and rather than look here I decided to try to do things the hard way. It turns out it is quite possible to extract them under Windows after all, if you want to.

The .sea.bin file is, to be precise, a MacBinary-encoded DiskDoubler archive. You can get rid of the MacBinary encoding using this progr am, specifically by invoking
"macbinconv.exe -mb [whatever].sea.bin -dfrf [whatever].dd [whatever].rsc"
This will put the DiskDoubler archive (without its .sea stub) into [whatever].dd .

It turns out the DiskDoubler archive can in turn be extracted with The UnArchiver, available for Windows as a command-line utility. In this case you need to run
"unar -k skip [whatever].dd"
The result should be the decompressed disk image.

I was thinking The Unarc hiver (and its Windows port) might be news here, but after a bit of searching it turns out people have posted about it before. I reckon it could be handy in dealing with Stuffit 5 archives and environments where Expander 5 will not run: just use The Unarchiver in Windows to unpack all the files with MacBinary encoding, and then un-MacBinary them using Expander 3 (or whatever) on the Macintosh side.