Help on the first building of boats and the reason for the difference in hulls

Does anyone have the reasoning behind the building of the different hulls of the boat and the wakes they leave? My son is doing a research paper and has to know the reasoning behind them thank you if you can help

 

The Difference in Hulls

Hi Moxie:

One distinctive hull design, the flat bottom or Sharpie, started as shallow draft work boats for use in shallow bays and rivers along the East coast of the U.S. Many flat bottom boats have built been as pleasure craft or converted from work boats to use as pleasure craft. If kept narrow in beam they are reasonably fast and seaworthy in larger sizes; 30 ft and larger.

Probably the most significant factor in the birth of the flat bottom hull was the simplicity and low cost of construction.

Good luck, Bill

 

The very first boat was likely a log a stone age guy took advantage of as it drifted down a river. Then some, protruding brow kind of fellow got the bright idea of tying a few of these magic logs together with vines and the first step in development of boats came to pass. As in all things, the folks who dream up the neat stuff we enjoy in life can't leave well enough alone and make adjustments. Most of this "design development" is to address problem areas or increases in efficiency, cost cuts, material use, strength, performance, comfort, looks, frankly what ever dances in the hearts of the engineers. Engineers generally just like to change things. Sort of like the kid who HAS to take apart each and every toy he owns (I was one of those) to see how it works and if it could be made better. Think of this as the Tim Allen on "Home Improvement" syndrome.

Some hull forms clearly are intended for simple construction, others mix in design elements for speed, comfort, safety, durability, record breaking, etc.

All boats are a set of compromises that have to be balanced by the designer to meet the design request, obey certain laws of physics, fit in a the budget, fit in the refrigerator and still float with the deck planks facing up, with a level of safety and performance the client desires.

Each hull form has its own set of characteristics effecting the way water and air interact with the craft as it passes through or over the water. This leads to some hull forms making different wakes then others. A very efficient hull will leave very little wake and thus require less power to propel, a well designed canoe will have a slight wake for example. Most powerboats currently seen on our waterways are planning craft. This is a hull form that is forced up over it's own bow wave and then skims over the surface. To do this requires lots of power and because of the abundant power available in the modern powerboat the hull needs not be as "clean" or efficient as it could be, which produces a big wake. A displacement boat is a craft that hasn't the power to over come the limits of it's own wave system and is destined to putter along at a speed defined by it's length on the water. Most sailboats are displacement hull forms and the shapes are very "clean" compared to powerboats and they leave much softer, lower wakes.

Some boats beat the rules or get around the limits of there designs. Some sailboats work in both displacement mode and when the conditions are correct also can get up over their bow wave and plane at much higher speed. Other tricks are to increase the length to width ratio, fins of every shape and size, multiple hulls, all in an effort to get more from the design. There are many exceptions to the rules and quite a bit of math involved, but the average person who got good grades in high school math can handle it.

Good luck,

 

hull configurations

Hi! Moxie:

Did you receive enough information on the reasons for the various boat hull shapes? I mentioned only the flat bottom design thinking others might respond with the reasoning behind at least some of the other shapes. If you need more information let me know.

Bill Buchanan

 

Yes Bill, we did some research and also he had to carve out wooden boats .. tomorrow the paper is due and March 27th is the science fair .. thanks for you help