Accurate measurements are now more central than ever to Canadian boat registration. Recent regulatory updates from Transport Canada have changed how tonnage is calculated for boats under 24 metres, directly affecting how owners register, transfer, and maintain compliance.
At National Vessel Registry Center Corp., our online portal makes it easier to access and submit the correct forms even as the rules change.
The “Keel Notch” Directive: SSB No. 17/2025
Transport Canada’s Ship Safety Bulletin No. 17/2025 introduced specific guidance on Tonnage Measurement Depth (TMD), particularly addressing attempts to alter keel structures to influence Gross Tonnage (GT).
Structural modifications were being introduced along the keel—specifically notches or discontinuities—designed to influence how Tonnage Measurement Depth was calculated.
Tonnage Measurement Depth (TMD) is one of the three primary dimensions used in simplified tonnage calculations. Because depth directly affects Gross Tonnage, altering it can change how a boat is classified under Canadian maritime laws.
Some of the tactics used include:
- Keel lines that were intentionally interrupted
- Structural cut-ins meant to shorten the apparent depth
- Attempts to lower Gross Tonnage thresholds
- Situations where altered measurements could place boats into reduced fee or regulatory categories
These changes were not cosmetic. They were designed to influence regulatory classification.
The Regulatory Objective
The perceived goal behind keel notches was straightforward:
- Reduce the official TMD
- Lower calculated Gross Tonnage
- Potentially fall under less stringent regulatory brackets
- Reduce associated compliance costs
Gross Tonnage affects more than paperwork. It can influence inspection requirements, equipment standards, and eligibility under certain frameworks. That is precisely why Transport Canada addressed the issue directly.
The Updated Measurement Standard
Transport Canada’s position in SSB No. 17/2025 is clear:
- Discontinuities in the keel do not alter the official depth measurement
- If a notch exists, measurers must project the original keel line
- TMD is taken from the underside of the deck to this projected line
- Artificial structural interruptions are disregarded for tonnage purposes
This clarification reinforces that tonnage reflects the boat’s true structural form—not modifications intended to affect calculations.
For owners pursuing Canadian boat registration, this means depth must reflect the original, continuous keel line even if alterations have been made.
July 1, 2026: The End of Assigned Formal Tonnage
A significant regulatory transition is approaching. Beginning July 1, 2026, Assigned Formal Tonnage (AFT) will no longer be available for newly registered boats.
The Previous System
For many years, boats under 12 metres could rely on a simplified tonnage assignment based solely on length. This was known as Assigned Formal Tonnage.
Under AFT:
- Length alone dictated Gross Tonnage
- Boats under 8.5 metres were typically assigned 4.99 GT
- No physical breadth or depth measurement was required
- The process relied on standardized tables
It was efficient and predictable, but it did not reflect actual hull dimensions.
The New Standard
After July 1, 2026:
- AFT will no longer be permitted for new registrations
- Every qualifying boat must use the Simplified Method (Form 4A/4B)
- Alternatively, a formal measurement by an appointed measurer will be required
- Breadth and depth must be physically measured
This marks the end of automatic tonnage assignments for newly registered boats.
If you are completing Canadian boat registration after this date, you must calculate tonnage using actual hull dimensions. There will be no shortcut based solely on length.
Measuring for Simplified Tonnage
With AFT phased out, accurate measurement becomes essential. The Simplified Method uses three dimensions:
- Tonnage Measurement Length (TML)
- Breadth
- Tonnage Measurement Depth (TMD)
These are applied within Transport Canada’s formula to determine Gross Tonnage.
Tonnage Measurement Length (TML)
TML is not the same as overall length advertised by manufacturers.
To determine TML:
- Measure from the fore side of the stem
- Extend to the aft side of the stern
- Follow the hull structure—not attachments
- Exclude removable fittings
This length must represent the structural hull boundaries. Even small discrepancies can affect calculated tonnage. Accuracy is critical when submitting forms through our portal for Canadian boat registration.
Breadth
Breadth represents the widest part of the hull.
When measuring breadth:
- Identify the maximum width of the hull
- Exclude rub rails and removable guards
- Measure at the widest structural section
- Ensure the measurement is perpendicular across the hull
Breadth is typically straightforward, but it must reflect structural width rather than add-ons.
Tonnage Measurement Depth (TMD)
TMD has become the focal point due to SSB No. 17/2025.
To measure TMD properly:
- Start at the underside of the deck
- Measure vertically downward
- Extend to the projected continuous keel line
- Ignore artificial notches or cut-ins
If a notch exists in the keel:
- Project the original keel line as though uninterrupted
- Measure depth to that projected line
- Do not use the lowest point of a cut-out
How Tonnage Affects Classification
Gross Tonnage influences more than a number on a certificate.
It may determine:
- Whether a boat qualifies for the small vessel register
- Inspection or safety standards
- Regulatory thresholds under Canadian maritime laws
- Certain operational requirements
It does not replace a pleasure craft licence, nor does licencing substitute for formal registration. These are separate frameworks under federal law, each with its own purpose.
Our portal provides access to the forms required for registration pathways so that owners can file properly based on their boat’s intended use and classification.
Boat Registration Transfer and Updated Measurements
Changes in measurement rules also affect ownership transitions.
If you are completing a boat registration transfer, updated tonnage calculations may be required when:
- Structural modifications have occurred
- Registration status changes
- A previous Assigned Formal Tonnage no longer applies
- The transfer takes place after regulatory changes take effect
When submitting transfer documentation through our service, ensuring that measurements comply with current Transport Canada standards is essential.
Bareboat Charters and Tonnage Considerations
Tonnage may also affect arrangements involving bareboat charters.
In certain scenarios:
- Gross Tonnage can influence regulatory oversight
- Charter structures must align with registration classifications
- Operational control arrangements intersect with federal compliance requirements
While charter agreements are separate legal arrangements, accurate registration status remains foundational.
Our service provides access to the appropriate filing pathways when registration updates are necessary.
How Our Portal Supports Canadian Boat Registration
National Vessel Registry Center Corp. operates as an online portal designed to simplify interaction with Transport Canada’s registration framework.
Through our platform, you can:
- Access registration forms required under federal standards
- Submit Simplified Tonnage calculations
- File documentation for initial registration
- Complete boat registration transfer submissions
- Pleasure craft licence applications
- Update registration details as required
With the end of Assigned Formal Tonnage approaching, proper submission of Simplified Method forms becomes essential for Canadian boat registration compliance.
Preparing for the 2026 Transition
Boat owners planning future registrations should consider acting before July 1, 2026, if Assigned Formal Tonnage remains relevant to their situation.
After that date:
- New registrations must use measured breadth and depth
- AFT will not be available
- Simplified Method forms will become standard
- Measurement precision becomes unavoidable
Canadian boat registration is entering a phase where structural measurements carry greater weight than ever before.
Our portal is structured to accommodate these updated requirements, allowing owners to submit the correct forms under current rules.
Staying Aligned With Canadian Maritime Laws
Transport Canada’s bulletin reflects broader federal oversight under Canadian maritime laws. Accurate tonnage ensures fair classification, consistent enforcement, and regulatory integrity across the fleet.
For boats under 24 metres:
- TMD must follow projected keel lines
- Breadth must reflect structural width
- Length must be measured properly
- Simplified Method forms must be completed accurately
Each of these elements now plays a central role in Canadian boat registration compliance.
As regulatory standards evolve, precise measurement and correct filing remain the foundation of lawful registration across Canada.