1. What is Gross Tonnage?

Definition: Gross tonnage (GT) is a unitless index related to a vessel's total enclosed volume, calculated using a simplified ITC formula.

Purpose: It represents the overall size of a vessel and is used for regulations, safety rules, and port fees.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( GT \) — Gross Tonnage (unitless)
• \( K \) — Coefficient based on vessel size (typically 0.2–0.3)
• \( V \) — Total enclosed volume (cubic meters)

Explanation: The total enclosed volume is multiplied by a coefficient that accounts for the vessel's size and type.

3. Importance of Gross Tonnage Calculation

Details: GT determines manning requirements, safety regulations, registration fees, and port dues for vessels.

4. Using the Calculator

Tips: Enter the coefficient K (default 0.25) between 0.2-0.3 and the total enclosed volume in cubic meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between gross tonnage and displacement?
A: Gross tonnage measures enclosed volume, while displacement measures actual weight of water displaced by the vessel.

Q2: How do I determine the correct K coefficient?
A: Use 0.25 for most vessels, 0.2 for smaller boats, and 0.3 for large ships with complex spaces.

Q3: What's included in total enclosed volume?
A: All enclosed spaces below deck and in superstructures, measured to the inner side of the shell plating.

Q4: Is this the same as net tonnage?
A: No, net tonnage deducts non-cargo spaces and represents earning capacity.

Q5: How accurate is this simplified formula?
A: It provides a good estimate, but official tonnage requires detailed measurement by certified surveyors.