Page 109 - (DK) Danger! Open with Extreme Caution!

Shipwrecks What sinks a ship? Taking on water is an obvious problem—large waves can break over the sides of a vessel, and leaks can let water in. Storms can toss a ship against the rocks, while a navigation error resulting in a crash can cause rips in the hull that let water pour in. Plug up the holes and ensure that more water is going out than pouring in or you’ll soon get that

long as the boat is stable and
the boat to make it float. As
water pushes up against
and cargo is distributed evenly,
the weight of its passengers
Maritime navigation Boats have been around for a very long time, and navigation as a science is at least 5,000 years old. The astrolabe (an instrument used in navigation that showed the positions of the planets and stars at a given time) was highly developed in the Islamic world by 800 CE. About 200 years later, the Chinese were using a magnetic compass for navigation. By the time the great age of exploration ended in the early 17th century, ships and navigators we

buoyancy (pushing up), weight (pushing
Boats float using pairs of forces, too:
down), thrust (moving forward), and
water will float if it displaces an amount
Buoyancy
of water equal to its own weight; if
Staying afloat drag (resisting motion). An object in water, so very little of it must submerge Thrust The weight of the boat pushes down Weight
a boat weighs 2,200 lb (1,000 kg),
2,200 lb (1,000 kg) of water. A boat’s
average density is light compared to
it will sink until it has displaced
before it has displaced its weight.

against the water to displace it.

DANGEROUS JOURNEYS 109
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