Jim, the history of the YT files seems to be a long and sordid tale, according to some. At one time in the past, there was a web site which contained scans of pages from the YT magazine concerning various model construction projects. Those files could only be considered as a starting point for construction of one's own model kit. The files were condensed by layering up to three sets of parts on a single page using a different ink color for each page. None of the parts were colored, and whenever possible the magazine futher "condensed" the information by showing only one half of a part if it was symmetrical around one of its axes, and on parts where both left hand and right hand versions existed, would print only one of those parts, leaving it up to the builder to figure out the part needed a mirror image duplicate for the kit to be complete. All in all, it is one hell of a drafting exercise to get from the magazine pages to a buildable model kit. Making things even worse, many of the smaller parts were not included other than in the building instruction drawings, leaving actual design of those parts to the builder.
At the time I obtained the files, there was considerable debate whether the site containing those files was a pirate site or not. General concensus of most of the papermodeling groups at the time was the site was "legitimate." From many forum postings during that time period, any attempt to communicate with YT magazine to gain permission to post files of kits created from those files, etc., were met with deafening silence on the part of YT. In any event, apparently YT eventually brought pressure on the site to shut down; however, I have noticed that at least one prominent papermodeling web site not affiliated with the YT magazine has offered downloads of kits they created from the YT sketches from then to present date with absolutely zero flack from the copyright gestapo. There is a little more discussion of these files in my article on construction of the Arktika. My own standpoint on the issue is that my redrawing the files for personal use is no different than my having done so from a library's copy of the magazine, and is consistent with the intent of the YT magazine regarding use of the publication.
There are several other modern merchant (or at least nonmilitary) subjects that were posted....the Arktika nuclear powered icebreaker, a LASH container ship, a Project 19620 river ship (see my posting of the build I am doing of that one), and a couple of trawlers, along with several historic ship models (trireme, viking ship, cog, caravelle, etc.).
The Jaguar is pretty close to completion....however, too many other projects keep getting in the way. Tim's malady is contageous. The lifeboats are complete, just not glued to the davits. The tiddly little bits are about complete, with exception of another four or five water cannons, which are the biggest reason for suspension of the build. I wasn't happy with the way the first one came out, using the patterns provided in the original YT files. They really need to be redesigned, which shouldn't take too long to do, but so far things more interesting keep me diverted. And, there are the various wire parts (antennas, and what appears to be a fairly extensive water piping system) and the propulsion parts left to go. All things considered, two or three good evenings of work could get it completed....just need a bit of motivation (and a few fewer distractions) to get it there.