Artikel 19

If, as is generally the case, it is impossible to measure the total tonnage length direct between its extreme points, having determined these and marked them on the tonnage deck, the foremost and aftermost parts of the length from the extreme points to a bulkhead, hatch-coaming, etc., as found practicable, should be measured.
In ships with a normal sheer, the remainder of the length shall be measured by means of a tape laid on the tonnage deck, or by a line stretched as tightly as possible from forward to aft. This length is to be measured between the bulkheads, hatch-coamings, etc., to which the foremost and aftermost parts of the length are measured. The tape is laid, or the line is stretched, clear of all obstacles, parallel to the middle plane of the ship, on or above the tonnage deck or its continuation line. In case a line is used (which must always be done if the sheer is excessive) it should be stretched from forward to aft. The length of the line is measured by means of measuring rods or tape. The tonnage length is obtained by adding the length of the foremost part, that of the part measured either by the tape or on the line, and that of the aftermost part.