Not to be confused with the weight (displacement) of the vessel, gross tonnage is a measure of the internal volume of a vessel, and is one of the key attributes used for implementing marine safety regulations. To a person who deals with this infrequently the rules can seem a bit of a maze, and as an appointed tonnage measurer, I receive plenty of calls from people needing advice about vessels less than 24m (79’9”) long, and what to do about it.

Why would you need to determine and report tonnage of a vessel?

  • If it’s financed with a marine mortgage
  • If you plan to use the vessel for commercial purposes
  • If the vessel has been imported to Canada
  • If the vessel is newly built
  • If its principal particulars or propulsion have changed
  • If the vessel is to be registered or re-registered

A quick summary of the rules:

For vessels Less than 12m long

You can use the assigned formal tonnage method.  This provides a gross and net tonnage in accordance with the length of the vessel.  This can be done by the owner, and submitted directly to TC as a part of the registration package.

For vessels 12-15m long

If you have a monohull vessel with a deckhouse having a single level (or no deckhouse at all), and your length is less than 15m (49’3”), then the owner can submit a tonnage report themselves using the simplified tonnage form (4A).

Bear in mind if yours is a multi-hull, or it has a deckhouse with more than one useable level (a flybridge is included as an additional level), then you likely be required to hire an appointed tonnage measurer to survey the vessel and submit a tonnage report.

For vessels 15m-24m long

When a vessels length is 15m or longer, an appointed tonnage measurer is required to measure the vessel, perform the calculation, take photos, and prepare a report. The report must include a cover letter for Transport Canada, a Certificate of Tonnage, specific photos of the vessel, and the appropriate form including the measurements and calculation.

The tonnage measurer must measure or reasonably validate the length, breadth, and depth, often requiring the vessel to be out of the water.  In cases where there are convincing corroborating documents (recent reports, photos, surveyor reports) that can support a validation of the depth this may not be required, but this is rare, and there is no guarantee that Transport Canada will accept such a method.

For vessels 24m and longer

For longer vessels the vessel’s actual volume must be calculated and measurements validated by an appointed tonnage measurer.  This requires a detailed analysis of vessel plans (lines plan and/or structural plans) and most often is performed using specialist CAD software to prepare a 3D model.  The volume of all of the vessel’s spaces are calculated and used in an equation to find Gross and Net tonnage.  Deductions may be made based on the usage of compartments.

Note: An owner can elect to use this method for any vessel size, although it rarely makes financial sense to do so, as it’s significantly more expensive and there are few cases where this would benefit. 

The methods for determining a Canadian vessel’s gross tonnage have changed over the years.  If you think your vessel is registered with a tonnage that’s higher than other similar vessels measured more recently you may benefit from a review of the vessel’s gross tonnage.

More details, and a list of tonnage measurers may be found at TC’s website here.

Contact CMDL for a quick consultation to find out if this might apply to your vessel.

info@capilanomaritime.com

604-929-6475

Dwight Organ, HNC 
Appointed Tonnage Measurer 
Marine Eng. Technologist, B.Tech, BSC, D.MSD.