3 ms·
When it comes to stability there is a crucial handicap between ships and icebergs. The former have non-uniform mass, so it is possible for a ship's center of ma
by praptak 6y ago
When it comes to stability there is a crucial handicap between ships and icebergs. The former have non-uniform mass, so it is possible for a ship's center of mass to be below its center of buoyancy. That's why ships have ballast - it lowers the center of mass relative to the center of buoyancy.
An iceberg is uniform, so its center of buoyancy is always below its center of mass. This makes its stability trickier, as it relies on changes in the shape of the buoyancy to follow the center of mass when disturbed.
A ship is a pendulum, an iceberg is an upright stick balanced on one's nose :)
- chrisdalke 6y agoGood point -- The way I described it really applies to _any_ object floating in water. I don't have much experience with ship design, but on small boat design you can rely mostly on the geometry of the boat to produce a sufficient righting moment even with a very high center of mass. Some off-shore speedboats have really incredible self-righting because they've been designed to always have positive stability at all angles. One of my favorite videos of this in action: https://www.youtube.com/watch?v=Y2i1fOJ-itw https://www.youtube.com/watch?v=Y2i1fOJ-itw
- sgtnoodle 6y agoIt's possible to engineer a stable boat in this simulation based on that principle for stability. https://ibb.co/T1KG5DM https://ibb.co/T1KG5DM The trick is to draw a low-mass object with high displacement, which happens to be possible because of the existence of, uh, anti-iceberg? that has negative mass.
- praptak 6y agoYes, small boats are often constrained by shallow water, so they cannot have too much ballast not to mention things like bulb-keel. This means the hull needs to be sufficiently broad and flat.