Anything that is denser (mass/volume) (ignoring shape). (A ship floats in water, but steel does not; yet a ship is made from steel -- shape.)

small water displacment compared to ships size

They float because of the air inside the ship which decreases the overall density of the ship which makes it float

It depends on how the substance is shaped. Take 40,000 tons of steel. If you shape it into an ingot, it will sink. Shape it into a ship and it will float.

An object will float if it has a density that is less than that of water. Or whatever liquid it is placed on. In the case of a ship, that includes not just the steel, but the entire ship - including air trapped inside the ship.

The ship has enough gas in it to keep it afloat.

The material used to make the ship and the shape of the ship are some of the things that displace water therefore making the ship float on water.

Because the buoyant force on the ship is greater than the weight of the ship .

It depends on the weight, shape and size of the ship.

The shape of the ship allows it to float. Imagine a ship that was just a big block of steel, If you put that steel block into water, it would sink because it is denser than water. Ships are built with a hollow shape. The amount of steel is the same, but the hollow shape decreases the boat's density. Water is denser than the hollow boat, so the boat floats. Shaping the block into a hollow form increases the volume occupied by the same mass, which results in a reduced overall density. The ship floats because it is less dense than water.

What it's made of makes no difference. It can be 4-inch plate steel. If it can push aside enough water that weighs as much as the ship weighs, then the ship will float.

Not as long as it's still in the shape of a block. But if you re-shape it into the shape of a cup ... whether round or rectangular ... it will float, because it displaces much more water than a block does. If your cup-shape is done artistically and with care, people may call it what it looks like ... a little "boat" or "ship". Those objects are usually made out of re-shaped blocks of steel.

Steel is denser, thus heavier than water, so it sinks. However a ship can float because it displaces more water than it's own weight, replacing the weight of water with air inside the ship, which is lighter than the water it displaces. If the ship were filled with water or even steel it would sink. The spoon doesn't displace enough water to float.

Well, buoyancy is capacity to float in liquid. So the object needs to have air to make it float an example for an boat the Titanic for example was really heavy it was made out of steel so it had air in the bottom to make the ship float.

The fact that a large steel ship will float is because of its shape. The ship displaces a huge volume of water equal to the volume of the submerged part of the hull. If the mass of the ship is less than the mass of the displaced water, the ship will not sink any lower so long as water is unable to enter the submerged portion of the hull. The mass of a pebble is more than the mass of the water it displaces, so the pebble sinks.

Because of buoyancy. Even though the steel of the ship weighs a lot more then water, the ship also has a lot of air in it (the ship is not a solid chuck of steel), the lightness of the air off sets the heaviness of the steel to allow it to float.

It depends. A steel ship will float just fine, so will an iron one(i.e. Old Ironsides). It all depends on the size, weight, and buoyancy of the ship.

A needle is fully metal whereas a ship is hollow so it floats

Ships are designed to float in all types of water, regardless of the density of the water or that of the ship.

The density is not directly relevant. Otherwise, ship made of steel would not float on water.

the surface area of a ship displaces more water than the weight of the ship. if the ship was solid steel (and not hollow) it would sink.

In between of the steel there are other materials - like air. What counts is the average density of the ship (including empty spaces in between), not the density of its densest component.

It's shape displaces the entire weight of the boat at the waterline.

It is due to water displacement, a ship which weighs many thousands of pounds can float because of the design. The hull of the ship displaces the water without letting it into the hull.

Because of buoyancy. Even though the steel of the ship weighs a lot more then water, the ship also has a lot of air in it (the ship is not a solid chuck of steel), the lightness of the air off sets the heaviness of the steel to allow it to float.