The Maritime and Shipping Branch of Transport Canada has issued a bulletin to clarify the measurement of tonnage measurement depth (TMD) for vessels less than 24 meters in length. The main concern is that some shipowners have attempted to minimize their vessel's tonnage by making notches in the keel, which can affect the TMD measurement.
To resolve this issue, Transport Canada wants to provide a clear explanation of how they measure TMD. 1 of TP 13430, Tonnage Measurement Depth (TMD) is defined as the depth of a vessel measured at the middle of the tonnage measurement length (TML) from the top edge of the upper deck at the side of the vessel to the bottom of the keel.
If there is a notch or any other discontinuity in the keel, measure TMD to the continuation of the line representing the bottom of the keel, which corresponds to the projected line of the keel. This clarification aims to ensure that shipowners and operators understand how to accurately measure their vessel's tonnage measurement depth.
It is recommended to consult with an appointed tonnage measurer or Transport Canada before making any modifications to the vessel. The bulletin provides a clear explanation of the TMD measurement process, which will help prevent any potential issues or disputes related to tonnage measurement.