The unloading was completed without any further difficulties.
The embarkation, however, was a more difficult matter. For this careful calculations on the part of our expert submarine embarkation specialist, shipping engineer, Prusse, of the Germania dock, were first necessary. Every pound of the varying weights and sizes of the goods to be loaded had to be reckoned up before being stowed in the space particularly appointed for them, in order to prevent an unequal trimming of the boat.
An absolutely exact storing was necessary, inasmuch as the whole loading space was very limited, and every box and sack must be held firmly in its position. Otherwise the most unpleasant occurrences might arise, either during a storm, by sudden submersions at a steep angle, or any other incidents, which might seriously impede our navigation.
An embarkation of this kind therefore was bound to be a lengthy affair.
The whole cargo, sacks and boxes, had to be carried by hand by the niggers through the narrow hatchways. The goods had first to be weighed, piece by piece, each separately—the weighing-inspector taking notes meanwhile and calling out the number of weights, which were then carefully indexed.
This indexing was part of a specially thought-out plan, according to which the whole packing was exactly carried out, and the accuracy of this plan was then tested by a submersion and boat-trimming test, for which our mooring-place had just sufficient depth of water.
For this test the crew all took up their submerging stations, the submersion tanks were slowly opened and the boat flooded with just sufficient water to make her float, the conning-tower hatch still remaining above the surface.
In this way the hull of the boat is made to oscillate by means of the different water loads of the two trimming tanks, and from this one can judge if the balance of the boat is properly adjusted. If after this it is found necessary to alter the weights, the cargo is moved accordingly. One last submerging and trimming test must then follow, in order to make sure that the loading of the whole boat agrees in every detail.
Thus her two thousand tons are brought into perfect adjustment in the fluctuating displacement of the water.