Well, I haven't looked at the NPC nations, but here are the PC nation ships which have a cross sectional hull strength of < 0.50 which are given inside the encyclopedia. I think I got all of the ships, regardless of date thus I added the date of the designs as well. Russia's 1916 Mediniy is the lowest at a cross sectional of 0.35.
I have also included ships in the list that use the hull strength <1.00 with a speed <24 knots. I think in a number of cases this was done due to the small size of the ships (for example, the RSAN R-class is mere 100 tons). A few nations do not have sims of the ships so I'm not sure if they are 'correct'.
Marek, it is funny that those designs of Romania and Yugoslavia are foreign designs.
:-)
Atlantis: 1919 Basillone = 0.43, 1919 Admiralty Type 2 = 0.43, 1928 H class = 0.48
Australia: 1928 HMAS Aclarity = 0.49, 1917 HMAS Spencer = 0.49
Denmark: 1918 D 13 = 0.44, 1917 Sohunden = 0.46, 1915 D 9 = 0.45, 1912 D 5 = 0.49
France: 1914 Ouaseau <1.00 at 21 knots
Italy: 1925 rebuild Bari = 0.47
Netherlands: 1900 Z1 = 0.45 (retired), 1903 Z13 = 0.47, 1909 Z25 = 0.47 (though its reconstruction >0.5), 1911 F1 = 0.46
Nordmark: 1918 20-class = 0.49
Philippines: 1898 Gazelle <1.00 at 21.48 knots
Romania: 1905 Solitario = 0.49
Russia: 1904 Bucharskiy = 0.47, 1905 Sibirsky Strelok = 0.46, 1904 Zorkiy = 0.45, 1908 Pion = 0.49, 1912 Gvozdika = 0.46, 1916 Tyulpan = 0.45, 1920 Lilya = 0.46, 1916 Mediniy = 0.35!!
South Arica: 1926 UJ <1.00 at 19.95 knots, 1928 R < 1.00 at 21.35
Turkey: 1928 Agri = 0.44, 1925 S-1 1 at 16 knots and cross = 0.39, 1916 Kocatepe = 0.46, 1909 Demirhisar = 0.44, 1907 Samsoun = 0.45
USA: 1909 Paulding = 0.45, 1916 Caldwell = 0.44, 1917 Wilkes = 0.43
Yugoslavia: 1918 D 13 = 0.44