Principles and application of channel depths in Finland

New instructions for principles and application of channel depths in Finland

The Finnish Transport and Communications Agency Traficom publishes the new instructions "Principles and application of channel depths in Finland", 1 November 2021. These instructions supercedes the previous instructions from 2011, "The channel depth practice in Finland - principles and implementation (4955/1021/2011)". The new chart datum N2000 is included in the instruction, additional to existing chart datums. The new instructions enter into force 15 November 2021, and shall be applied nationwide, regardless of the chart datum used.

In the new instructions, the term Authorised draught is replaced by the term Design draught. The design draught refers to the planned draught at which the channel's design vessel can normally use the channel; however, different draughts can be used if the conditions allow it. Portrayal of channel depths in the new N2000-charts is described in the new instructions. Design draughts for merchant fairways (classes 1 and 2) will no longer be included in N2000-nautical charts.  For these channels the safe clearance depth (minimum depth) is presented. Additional fairway data, including the design draught, will be presented in a separate nautical publication, published by Traficom. Also channel draughts presented in current charts, referenced to mean sea level (MSL), shall be considered design draughts according to the new instructions. Encoding of channel information in electronic charts is also renewed, as previously notified October 10 2021 in NtM 258/2021.

Clarifications of fairway use and responsibilities, especially regarding the design draught,  are added to the new instructions. The instructions are based on the principle that the actual water level at the time of navigation is taken into consideration as an increase or reduction in the channel's indicated safe clearance depth and design draught. This principle is applied both for sea-areas and inland waterways. The Channel Authority is responsible for the channel and the safe clearance depths (minimum depth). The master of the watercraft is responsible for determining the draught of the watercraft.