Artikel 20

The tonnage length having been ascertained, the position of the middle transverse section must be determined. This is done by measuring half of the tonnage length forward from the aftermost point, or aft from the foremost point of the length, in the same way as explained in Article 19. The middle point of the length is marked on the line and on the deck, and its distance from a bulkhead, hatchcoaming, etc., is determined. The work is then checked by measuring the second half of the length from the middle point in the same way. If the end of half of the length coincides with the extreme point of the tonnage length, this length has been accurately measured and the position of the middle transverse section correctly marked off. If the two points do not coincide, it is necessary to re-measure the tonnage length.
As an alternative method, the positions of the various transverse sections, as indicated in Article 21, may be determined by setting off upon the deck the common interval from each extreme point of the tonnage length, the position of the middle transverse section being found where such sections coincide amidships.