What's the difference between tonnage and weighlock?

Tonnage

Definition:

(n.) The weight of goods carried in a boat or a ship.
(n.) The cubical content or burden of a vessel, or vessels, in tons; or, the amount of weight which one or several vessels may carry. See Ton, n. (b).
(n.) A duty or impost on vessels, estimated per ton, or, a duty, toll, or rate payable on goods per ton transported on canals.
(n.) The whole amount of shipping estimated by tons; as, the tonnage of the United States. See Ton.

Example Sentences:

(1) This means for 80 records we have no destination details (accounting for 4% of the total tonnage for the year).
(2) Over the past decade Sheffield steelworks produced more steel than ever before, with a tiny fraction of their former workforce; and the container ports of Avonmouth, Tilbury, Teesport and Southampton got rid of most of the dockers, but not the tonnage.
(3) The tonnage values indicate that 13.8% of the wheat used in bread making came from Canada.
(4) The shipping industry will also see a tonnage tax hike and the industry’s preferential tax treatments phased out.
(5) The implications of the relationship between tusk size and age of an animal on the maximum sustainable yield in terms of ivory tonnage and in terms of the number of tusks are explored.
(6) I am also pleased to announce additional investment in Portsmouth Naval Base to prepare for the significant increase in tonnage as the home port for the Royal Navy’s aircraft carriers and destroyers.
(7) The WGC said it was the first time global demand had exceeded $200bn, and the highest tonnage level since 1997, according to the report.
(8) Abe has increased the defence budget for the first time in years, is overseeing an expansion of naval and coastguard capabilities (Japan's maritime self-defence force, or navy, is already the second biggest in Asia by tonnage), and has gathered expert support for a reinterpretation of article 9 of Japan's pacifist constitution to allow "collective self-defence" – meaning that if the US or another ally is attacked, Japanese armed forces will join the fight .
(9) A drop of 10% to 30% of wheat tonnage per acre is expected even if it starts raining heavily this weekend.
(10) To determine the intensity of benzene exposure, data on phenol content in the urine of people working at some big-tonnage enterprises has been analyzed.
(11) This report collates the evidence of safety now available and presents the data on Need, production tonnages and dietary intake levels.