Take a look:
I thought in my ignorance that Yacht word had an English origin and that yachting was born in England. I was wrong. It turns out that Yacht comes from Jacht. That's a Dutch word that means hunter and that's what they began to be: Very fast Navy Dutch boats to hunt pirates and transgressors on the shallow waters of Holland.
The full story:
"Yacht, from Dutch/Low German jacht meaning hunting or hunt, .. was originally defined as a light, fast sailing vessel used by the Dutch navy to pursue pirates and other transgressors around and into the shallow waters of the Low Countries.
They were also used for non-military governmental roles such as customs duties and delivering pilots to waiting ships. The latter use attracted the attention of wealthy Dutch merchants who began to build private yachts so they could be taken out to greet their returning ships.
Soon wealthy individuals began to use their "jachts" for pleasure trips. By the start of the 17th century "jachts" came in two broad categories—speel-jachts for sport and oorlog-jachts for naval duties.
By the middle of the century large "jacht" fleets were found around the Dutch coast and the Dutch states organised large 'reviews' of private and war yachts for special occasions, thus putting in place the groundwork for the modern sport of yachting.
Charles II of England spent part of his time in exile during the period of the Commonwealth of England in the Netherlands and became keen on sailing. He returned to England in 1660 aboard a Dutch yacht. During his reign Charles commissioned 24 Royal Yachts on top of the two presented to him by Dutch states on his restoration.
As the fashion for yachting spread throughout the English aristocracy, yacht races began to become common. Other rich individuals in Europe built yachts as the sport spread. Yachting therefore became a purely recreational form of sailing with no commercial or military function (see, for example, the Cox & King yachts at the beginning of the 20th Century), which still serves a broad definition of both the sport and of the vessel."
Back to the bathtube bow, even before those yachts, the Portuguese, between the XV and XVI century gradually changed the shape of the Caravela bow from its original shape, that comes from the Mediterranean tradition through the Arabs, from its more conventional shape to a bathtube bow shape. Many years ago I had read on an ancient treaty that the Caravela Bow should be well rounded to give a better ship and at the time I found that really odd. Well, not now
The posterior man of war and cargo ship, the Galećo (XVI and XVII centuries) also featured an even more pronounced bath tube bow:
Back to the word Yacht, it seems to be changing again of meaning. On the 50's and 60's yacht was a pleasure boat of some dimension, but a 40ft boat was already called a yacht, a small yacht but a yacht nonetheless. Now, at least in Europe, if someone is referring to his boat as a yacht and the boat has not more than 60ft, he is being pompous. The denomination of yacht seems to have been reserved now for large pleasure motorboats or sailing boats. Smaller ones are just called as sailing boats or motor boats.