The best source for info on the SLI DS IV might be Cape Cod Shipbuilding, the current builder of that boat.
www.capecodshipbuilding.com
Also check out the Day Sailer Association;
www.daysailer.org
The Day Sailer built by SLI (Sunfish Laser) was a pretty good boat quality wise, but definitely geared a bit more to the racing guys than us "daysailing" Day Sailier owners. The tiny hatch to access the cuddy is a great feature if you expect to capsize a lot like racers do, since it seals the cuddy better than the larger opening on the DS II or DS III, but access to the cuddy for storage suffered. CCSB has enlarged that opening to give much better access, still smaller than hte cuddy opening on my DS II, but a lot better than hte SLI setup.
The DS has been built by several builders over the years, well, the original DS (DS I) has been, O'DAY built it first in 1958 and continued with the same basic open design until 1970. For 1971 they decided to make the boat more "self-rescuing" (designed to be easier for the crew to right the boat and keep sailing after a rare capsize without outside help) by making the cockpit a part of the deck molding and reducing hte size of the cuddy opening, This also made the cockpit semi-self-bailing. The Day Sailer Class Association was not told of this upgrade before production changed and was upset since they felt it affected the "one-Design" aspect of the boat (new boats were now different fro mold boats). O'Day was forced to continue building hte original design alongside hte new "DS II". At the same time, a few DS Is were built by Cam-Am Sailcraft using hulls and decks molded by O'DAY under a DSA contract. Eventually, around 1977, O'DAY decided they did not want to build both versions and the DSA sought out a new builder for the DS I (incidently, the DSA did accept the DS II design as "class-legal" during hte 1971 model year), I think the next builder was Rebel Industries in Florida and they built the DS I based on a slightly modified version of the early (1958-60) O'DAY design. Rebel merged or was bought out by Spindrift around 1980 or so and Spindrift took over the DS I production. In 1983 O'DAY got in trouble with the DSA again by supstituting a different rudder on the DS II (blade was deeper) and they had to go back to the original blade shape but with a new upper section. In 1985 O'DAY really ticked-off the DSA when htey introduced the new "DS III" for the 1986 model year. The DS III was basically the same as the DS II but with more freeboard in the stern. Overall a better boat that than the earlier Day Sailer models (DS I and DS II) due to that increase in freeboard and with a roller-furling jib and jiffy-reefing on the main, easier to sail. However, that increase in freeboard was enought to make them non-Class-Legal, since hte hull design had been changed. The DSA never recognized the DS III as a true Day Sailer. Well, O'DAY still sold a lot of them! With the demise of O'DAY in May of 1989, the Day Sailer III molds were bought buy the Small-Boat Division of PEARSON Yachts and were joined in that division by the old AMF Alcort designs (Sunfish, Zuma, Force 5, Puffer, and Trac-Catamarans) that Pearson had also recently purchased from bankruptcy. With the demise of Pearson in February of 1991, the Small Boat Division was sold off and became SUNFISH-LASER Inc. This company had also bought the US building rights to the LASER class. In late 1991 or early 1992 SLI tried to get the DSA to accept the DS III as Class-Legal, but no dice. The DSA instead worked with them to create an updated version of the original DS I, and basically the result was a design that added the easier self-rescue feature of hte DS II to the original DS design. The cockpit was virtually the full depth of the hul like on the DS I, but sealed to the deck like a DS II or DS III. It was not self-bailing, but at least it did not flood the whole hull if swamped. The cuddy was closed off by a full bulkhead with a small access hatch to prevent flooding in a capsize. Two levels of rigging were offered, a Racing version with all kinds of racing type rigging (basically what a racing skipper would have put on a DS I) and a "Daysailing" version for the recreational type sailor. The CB was now controlled by a lever like the DS I had always had in place of the line-controlled CB of the DS II and DS III. Around 1994, SLI wanted to concentrate on Sunfish and Laser production and contacted the DSA to find a new builder for the DS IV (well ,the DSA still calls it a DS I..... but to me it is a different boat, hence I use the SLI coined "DS IV"). That led to Cape Cod Shipbuilding becoming hte builder (the molds though, are still owned by the DSA) in 1995. They continue to be the sole builder of the class, and build both a "Daysailing" model and a "Racing" model. Big difference is again the style of rigging setup including a "keel-stepped" and tapered mast on the race boat and a hinged on deck mast for the daysailing model.
Cape Cod Shipbuilding makes a very nicely finished ,quality boat and they get a pretty good price for them too! Around $12,000 for the daysailing model, higher for the racing model. I like the looks, but not the price! My biggest complaint is that the DSA insists that the boat be geared more to the racer, not the casual sailor like me, and it shows in the lack of mooring cleats (which O'DAY had as standard) and the need for an optional bracket to mount an outboard (O'Day had a molded-in "kicker-pit" in the afterdeck to allow clamping hte outboard right to the transom on the DS I and the DS II and III had no afterdeck allowing the motor to be easily clamped to the transom with no need for a bracket (I did add a motor board to my boat to angle the outboard better on the slightly reversed transom angle of the DS ).
I do have to disagree with the above post that claims the DS will not plane as Uffa Fos intended. Yes, George O'day did add (against Fox's wishes!) the cuddy, but as long as you don't stow too much heavy gear in the bow...... the DS will get up on plane on a broad reach or run under the right conditions (a little following sea helps a lot!), and I've done it a few times!
Well, long story.... but that is where the SLI boats fit in.
PS: O'DAY also upgraded the Widgeon and Javelin in 1971 just like the DS, making all 3 more self-rescuing, and for a breif time, they even refered to the "new" designs as WIDGEON II and JAVELIN II. I guess hte Javelin Class didn't object as loudly as the DSA?