three design changes that boats have undergone over time?

Answer 1

Construction material-Wood to steel, aluminum, fiberglass

Means of power-oars to sails to some form of power, first steam then to gas engines then diesel, two strokes

Hull designs- that is still to this day evolving constantly...well really all 3 are.

Answer 2

Early boats were small open vessels like canoes and rafts. In the pacific they added a support beam to a canoe and made outriggers. then people thought to use oars to move the boat along so as not to drift with the current. Over time boats got bigger and sails came into use to take advantage of wind power. Boats got bigger with sails and became true sea-worthy vessels. Eventually steam power came into play and that eliminated our dependency on the wind to keep the boat moving. During the civil war we figured out how to make ships out of metal and powered by steam. Progressing from there you come to todays super liners computerized and gps aided navigation systems that require only a skeleton crew to get the vessel to its destination.

Answer 3

Umm. Not sure exactly what you are looking for, but:

1)Boats used to be wood, but now they are metal or fiberglass.
2)Boats used to be powered only by people power or wind power, and now most have motors.
3)boats used to rely only on the stars and wind to guide them, now we have radars and GPS.