I can't give you a definative answer as to why some boats have such "sharp" bows. However I can explain a little of the "newer" shapes.



As you go from a sharp shape to a rounded shape (not to be confused with fineness ratio), you go up or down in efficiency. A sharp bow shape is just as inefficient as a very blunt shape. Of course all of this varries with the speed of the hull through the water. The trick is to find a shape that is optimized for a fairly wide range of hull speeds. Now that is a generic answer....



This is too, but....if you want a long one.... go get a book!



The maximum speed for a displacement hull is generally specicied by the fineness ratio (lenght to width) of the hull.



There are several web pages where you can "calculate" a theoretical hull speed for a displacement boat....well if you put in 20', it give you ~6 knots. Now we all have easily broken six knots. So, what gives? Well, they used a simple equation "Hullspeed = SqRt(LWL) X 1.34" Where 1.34 is the accentric factor for that hull. 1.34 is roughly the accentric factor for most monoslugs. A cat would be much higher so, this equation does us no good w/o the graph to get our accentric factor......so....now that I have rambled way outside that answer...



Ok, a destroyer or plumb bow shape allows for the max waterline hence the max speed for a given loa. Also, it allows more volume forward to keep the sails from pushing the bows too far down and reduces diving in waves. Not to mention... it looks cool.



all.... general answers, but if you want to know more... go get a book or ten....



Will_R