It may also be used to change the moments of inertia which affect motion in a seaway. It may also be used to modify structural load distribution, usually the longitudinal load distribution which affects hogging and sagging stresses. Ships īallast is used in surface vessels to alter the draft, trim, list and stability. In 1849 Abraham Lincoln, then an Illinois attorney, patented a ballast-tank system to enable cargo vessels to pass over shoals in North American rivers. The first documented example of a submarine using a ballast tank was in David Bushnell's Turtle, which was the first submarine to ever be used in combat in 1776. The concept has been invented and reinvented many times by humans to serve a variety of purposes. The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus. Airships use ballast tanks mainly to control buoyancy and correct trim. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels, and makes it easy for the crew to reduce a vessel's draft when it enters shallower water, by temporarily pumping out ballast.

JSTOR ( December 2021) ( Learn how and when to remove this template message)Ĭross section of a vessel with a single ballast tank at the bottom.Ī ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, to provide a more even load distribution along the hull to reduce structural hogging or sagging stresses, or to increase draft, as in a semi-submersible vessel or platform, or a SWATH, to improve seakeeping.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.

Air force micrometer tank