The ships were especially designed for interplanetary travel. They had simple nuclear powered engines and were equipped with artificial gravity. They utilized transistors as components. DY-100 ships were launched into orbit with booster rockets. In the 1990s, this class of spaceship was considered to be one of the most advanced.
At least some of the DY-100 ships were sleeper ships. In those a crew of at least 85 could be placed into suspended animation inside life support canisters prior to liftoff. The life support of the ship was turned off for the journey. The use of suspended animation was necessary up to approximately 2018, as it took years to travel from planet to planet in the solar system prior to that.
The production of DY-100 class ships began before 1996 and ended some time before the year 2000. A later generation of the class, the DY-500, was similar in configuration and some 23rd century Humans had trouble telling them apart, as did Captain James T. Kirk in 2267, before being corrected by Spock. (TOS: "Space Seed")
A model of a DY-100 appeared on a window sill of the office where Rain Robinson worked, at the Griffith Observatory in California in 1996. She also had a photograph of the launch of a DY-100 attached with tape to a cabinet. (VOY: "Future's End") A photograph of the same DY-100 launch was in the 602 Club, along with many other space achievements, like the NX-Alpha, the Phoenix, and the USS Enterprise (XCV 330). (ENT: "First Flight")
Ships commissioned Edit
|DY-100: SS Botany Bay|
|DY-245: SS Hatteras • DY-430: SS Urusei Yatsura|
|DY-500: SS Mariposa · HMS Lord Nelson (DY-500-B) · SS Hokule'a (DY-500-C)|
|DY-732: VK Yuri Gagarin · HMS New Zealand (DY-732 [N])|
|DY-950: DEV Eagle Valley • DY-1200: VK Velikan|
Background information Edit
All of the DY-100 ships were probably not sleeper ships, as the crew of the Enterprise was surprised to discover the Botany Bay to be one. That contradicts a bit with the computer display of VOY: "Drone", where the image of the ship is specifically labelled "DY-100 Sleeper Ship" (though the graphic might specifically refer to the Botany Bay).
The art department of Star Trek: Enterprise tried to convince the producers of that series to include the DY-100 class in the show. However, the producers refused to do so, believing this class looked too similar to a pencil. 
The original version of "The Ultimate Computer" featured a DY-100 class Woden as a Federation freighter. This appearance would indicate some of these ships were adapted into service by the Federation and remained in use at least as far as the 23rd century. Due to the retcon of the remastered version, it is impossible to determine if this was the case. Memory Alpha lists the Woden as an Antares-type starship, for the sole reason it was a more recent appearance from the production point-of view.
In Star Trek Spaceflight Chronology, it is stated that DY-100 was the first mass-produced spaceship of Earth. This production began in 1996. There were cargo, fuel and passenger containers the ship could carry. In the standard configuration, it was used between Earth and Luna. In an uprated mode, it was able to take man to Mars. A journey to Mars, when the suspended animation was used, took 937 days. In the Spaceflight Chronology, timeline specifications are given of an SS Copernicus of the DY-100 class. It served from 1995 to 2020. Specifications were length 100 meters, weight 2.72 million kilograms, ship's complement 22, and chemical/fission propulsion. Only the overall shape is similar to the Botany Bay. The Copernicus is probably intended to be the prototype of the class. Unlike the Botany Bay, the Copernicus had a built-in engine pack of six chemical boosters for lift-off. There is a discrepancy with the text and graphics, as the graphics show only four boosters.
Studio models Edit
The DY-100 was designed by Matt Jefferies. In sketches, it was referred to as an "obsolete tramp space freighter" or an "antique space-freighter". In fact, Jefferies once stated, in 1968, "The Botany Bay was actually designed before the Enterprise. It was a little idea that popped up and was labeled 'antique space-freighter'. Later on, we made it look like something else – a vehicle from the early 2000s. (Inside Star Trek, issue 4, p. 4) One sketch also included the numbers 418 on the hull of the ship. Jefferies was pleased with the notion of modular shipping crates that could be automatically loaded and unloaded without requiring Humans to venture into space. In the sketches, Jefferies envisioned that three additional cargo containers could be attached to complete the middle section arrangement. In fact, judging from the actual model, it appears that even a second set of containers could be attached behind the first. (The Art of Star Trek) In the original script of TOS: "Space Seed", dated 26 October 1966, this class was called "CZ-100" and almost perpetuated into the final script.  In effect, author James Blish, forced to work from non-final script drafts at the time, had to adhere to the "CZ-100" designation in a 1968 novelization of the episode, which he wrote, indicating that the class change had been a late decision.
Jefferies sold off his original design sketches on 12 December 2001 in Profiles in History's The Star Trek Auction, in order to raise funds for the charitable organization "Motion Picture and Television Fund".
Physical models Edit
The studio model of the DY-100 class, measuring 43×18 (aft section) inches, was mostly constructed out of wood, as was usual in that era, embellished with miscellaneous model kit parts and metal components. The leading edge of the "sail" (a naval term for the tower structure found on most submarines) features a corrugated metal foil and the engine pod includes metal "antennas" and masts. The model was not internally lighted and was finished in a brown/red-gray hue, though that finish was washed out into an overall gray on screen, due to bright lighting conditions in the studio and the use of the blue screen filming technique which caused light bouncing off the screen onto the model, an effect known as "blue spill". While not built by Jefferies, he did add the weathering on the model. Upon completion, the model was sent to Linwood G. Dunn's Film Effects of Hollywood, where the only footage of the model was shot, its one later appearance as the Woden in the original airing of TOS: "The Ultimate Computer" being stock footage of that shoot. (Cinefantastique, Vol. 27, No. 11/12, pp. 70-71) In the 2006 remastered version of the episode, the footage of the Woden was replaced by a newly constructed CGI model.
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The table-top model – smaller than the original and outfitted with booster rockets, used in the post-TOS references, first appearing in a Photoshopped launch photograph in Star Trek Chronology and subsequently in Star Trek Encyclopedia – was built by Greg Jein. (Star Trek Encyclopedia (3rd ed., p. 52)) The launch photo made subsequent in-universe appearances as a wall ornament in the episodes ENT: "First Flight", "Home", and VOY: "Future's End", the latter of which also featured the model itself as a desktop model in Rain Robinson's office. The (framed) photograph itself, part of a set of four, was offered up for auction as Lot 193, in the 40 Years of Star Trek: The Collection auction, estimated at US$200-$300, and was eventually sold on 5 October 2006, with a winning bid of US$3,000 (US$3,600 including buyer's premium).
Greg Jein, a life-long fan of Star Trek: The Original Series, was singularly well suited for constructing the desktop model, as he was the owner of the original studio model. (X) Jein had the original model over at his workshop in April 1988 for refurbishment, where amongst others he accentuated the brown-gray hull color.  It has made few public appearances, the first time, directly before its refurbishment, in the 1-3 April 1988 "Equicon '88 Science Fiction Convention" held in Los Angeles,  and after its refurbishment for the last time in 1992 when Jein loaned the model out to the Smithsonian National Air and Space Museum for their 1992-1993 Star Trek Smithsonian Exhibit and its 1993-1994 follow-up exhibition at the Hayden Planetarium, New York City. 
CGI models Edit
For the 2006 remastered version of TOS, a CGI variant of the model was used at CBS Digital, where digital animators worked with the model under the supervision of Niel Wray and David Rossi, for representation of the craft in its respective episode. The model was built by Finnish fan and digital modeler Petri Blomqvist, and was bought from him by CBS Television Studios for use in the series. Blomqvist's work was brought to the attention of Wray and Visual Effects Supervisor Michael Okuda by Technical Consultant Gary Kerr. The quality of his work was a compelling reason for the acquisition, as it saved valuable production time. Nevertheless, the digital animators still had their work cut out for them as Blomqvist's model was constructed in LightWave 3D software, whereas they used Autodesk Maya CGI software at the time, and had to translate the digital model from one format into the other, which inevitably led to some information loss. Additionally, they had to cut down on the resolution level of Blomqvist's highly detailed high-resolution model, in order to speed up computer rendering time. It, and the other models CBS bought from him for the project, has earned Blomqvist an official "Technical Consultant" credit. (Sci-fi & fantasy modeller, Vol. 26, pp. 49-50) Regarding the remastered version of the Botany Bay, according to Michael Okuda, "The top of the 'conning tower' now has a tiny circular docking port, very similar to those used on the real-life International Space Station. The docking port was added at the suggestion of a former NASA engineer who noted that a spacecraft built in 1996 would probably have included such equipment to dock at the station." (X)
Previously, in 2003, Doug Drexler had already built a CGI model of a DY-100 class vessel for a fan film in the Star Trek: New Voyages series. His model was later used for licensed Star Trek: Ships of the Line calendars and a book derivative of those publications. (X) A new CGI model was built by former Foundation Imaging employee Jose Perez in 2004 for a "Fleet File" article in Star Trek: Communicator issue 148 (pp. 62-65).
In a short story in the 1977 Enterprise Log 4 comic book an unnamed DY-100 class ship was depicted with the registry number FWB 52. The ship was part of a fleet of DY-100 class ships that were used to colonize planets in the Sol system. 
- Models – The Enterprise – behind the scenes bluescreen shots of various TOS models, including the DY-100
- SS Botany Bay miniature – photographs of the original model
- Length of DY-100 SS Botany Bay at Therpf.com, featuring photos of the model at Gregory Jein, Inc. taken by Scott Schneider
- DY-100 class at Memory Beta, the wiki for licensed Star Trek works
- CZ-100 at Memory Beta, the wiki for licensed Star Trek works
- DY-100 class at StarTrek.com, the official Star Trek website