Underdeck tonnage (UDT) is the measurement, in tons, of the space below a ship's tonnage deck and above its double bottom. In ships with two decks, the tonnage deck is the upper deck; though it is generally the second deck from above in ships with more than two decks.[1] Underdeck tonnage is applied using Simpson's first rule of ship stability.[2] It is measured in gross cubical capacity.[3]
References
- ^ "Underdeck tonnage – xSHIPx- Shipping News". Retrieved 2025-06-28.
- ^ "46 CFR § 69.109 - Under-deck tonnage". LII / Legal Information Institute. Retrieved 2025-06-28.
- ^ "Definition of UNDERDECK TONNAGE". www.merriam-webster.com. Retrieved 2025-06-28.
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