B 4 to 24

Bottom discharging Hopper barges
Name                           Dimensions lxWxD                              Year build                          Hopper volume
B 4                               40,0 x 6,92 x 2,5 m                             1951                                 250 m3
B 5                               40,0 x 6,92 x 2,5 m                             1951                                 250 m3
B 6                               37,0 x 5,95 x 2,3 m                             1951                                 200 m3
B 7                               37,0 x 5,95 x 2,3 m                             1951                                 200 m3
B 8                               37,0 x 5,95 x 2,3 m                             1951                                 200 m3
B 9                               43,0 x 7,50 x 3,0 m                             1952                                 300 m3
B 10                             43,0 x 7,50 x 3,0 m                             1952                                 300 m3
B 11                             46,0 x 8,50 x 3,5 m                             1952                                 400 m3
B 12                             40,0 x 7,00 x 2,5 m                             1952                                 350 m3
B 14                             40,0 x 7,00 x 2,5 m                             1952                                 350 m3
B 15                             46,0 x 8,50 x 3,5 m                             1952                                 400 m3
B 16                             37,0 x 6,00 x 2,5 m                             1961                                 200 m3
B 17                             37,0 x 6,00 x 2,5 m                             1961                                 200 m3
B 18                             37,0 x 6,00 x 2,5 m                             1961                                 200 m3
B 24                             40,0 x 7,00 x 3,5 m                             1953                                 350 m3
Groningen                    45,0 x 8,00 x 2,75 m                           1955                                 400 m3
Utrecht                         40,0 x 6,92 x 2,5 m                             1955                                 400 m3

The B4 - B5 - B 6 - B 7 en B 8 were build by Sleephelling Mij. Scheveningen.
Building numbers; 51 - 52 - 40 - 41 - 42
The B9 to  B 15 were the first self propelled bottom discharging hopper barges in the dredging industry and were equipped with a 225 BHP MWM engine. 
The B 9 - B10 - B11 and  B12 were build at shipyards in Groningen (NL)
The B14 was build at Worst & Dutmer in Meppel (NL)
The B15 was delivered by shipyard "De Liesbos" ( Amsterdamse Ballast Mij.) from Vianen (NL).

Off course the name "B13" was skipped, as sailing a vessel with that unlucky number was "not done" in the dredging world.

The  "Groningen" and "Utrecht" ( Building Nrs. 110-111) were build by Sleephelling Mij. Scheveningen and each of them was equipped with two MWM, 187 BHP engines.
Source: http://rboltje.nl/Onderlossers.html