Why is surface area important when designing a viking boat

The viking boat is basically formed by timber material, oak by overlapping together and the boat are usually made narrow type shape and the watertight.

The surface area is one of the important factor while designing the viking boat as they keep the surface area of the boat afloat.

The surface area of the boat is basically gives us an object that displaced water on its own boat weight and the water that are displaced become equal to the weight of the boat.