This photo shows SMS Odin under construction in Danzig in 1893. All the Siegfried-class ships were built with steel frames , planked over with teak. Then the teak was covered with armor plate, which made the ships iron clads rather than steel ships. When completed, the ships were 79 m (259 feet) OAL, had a14.9m (48.9 feet) beam, and drew 5.51m (18 feet), and had a top speed of about 15 knots. The crew was 20 officers and 256 men.
In addition to having a single stack, all the ships had a design feature that went back nearly 300 years, and is more often found in sailing ships. The feature is called tumble-home, which is the amount by which the sides of the ship above the waterline, roll in toward the keel line. The plans above show the tumble-home on SMS Hagen, which was the same on all the ships. The original reason for tumble-home in sailing warships was to provide room on the gundeck to operate the muzzel-loaded cannons of the 18th to early 19th Centuries.
All the ships carried the same armament, three 24 cm (9.4 inch) and six 88mm (3.5 inch) guns, shown above on SMS Beowulf. The placement of the six 88mm guns is the only noticable design difference among the eight ships.
In addition to guns, the ships were armed with four torpedo tubes. One mounted in the stern, shown above in SMS Ägir, and one in the bow, shown in the drawing below.
There were also two tubes mounted somewhere between the waterline and the main deck, one on each side of the ship, but I have never been able to locate them.
Another throw-back to an earlier age was the Rammsporn (Bow Ram) shown in the drawing above. It's the protrusion at the base of the stem, and as its name implies it was there for ramming an enemy ship.
The ships had an easy motion in moderate seas but lost considerable spped in rough seas and developed severe weather-helm. Weather-helm is the tendency of a ship to round into the wind, which the helmsman feels in the wheel because it takes more and more effort to hold the ship on coarse. As the weather-helm increases, the helmsman has to apply more and more lee helm. The standard practice in heavy weather was to heave-to and ride it out--just like a sailing ship.