Thursday, November 25, 2010

Hull types (ship & boat) part 1

for this part 1 i included with picture and more information about hull types. All the information and picture is gathered from internet sources and naval architecture book. I hope with this data all my member, friend can learn more and understand basic of the hull types. thank and i would love to be critic/ shared knowledge to improve my understanding..see ya!

Chine Hulls

These are hulls made up of flat panels (commonly made of plywood, or more traditionally with planking) which meet at a sharp angle known as the chine. Chined hulls range from simple flat-bottomed boats where the side and bottom are two distinct pieces (such as banks dories, sharpies and skiffs) to multichine boats. Multichine hulls allow a round hull shape to be approximated.

A chined hull consists of straight plates, which are set at an angle to each other. The chined hull is the most simple hull shape because it works with only straight planks. These boards are often bent lengthwise. Most home-made constructed boats are chined hull boats. A benefit of this type of boating activity is the low production cost and the (usually) fairly flat bottom, making the boat faster at planning. Chined hulls can also make use of a sword or attached keel.
            chine hull                 
chine hull  
  chine hull  

Displacement Hulls

Boats with displacement hulls move through the water by pushing the water aside and are designed to cut through the water with very little propulsion.
  • If you lower a boat into the water, some of the water moves out of the way to adjust for the boat. If you could weigh that displaced water, you would find it equals the weight of the boat. That weight is the boat's displacement.
  • Boats with displacement hulls are limited to slower speeds.
  • A round-bottomed hull shape acts as a displacement hull. Most large cruisers and most sailboats have displacement hulls, allowing them to travel more smoothly through the water.
 displacement hull  
 displacement hull  

Flatt Bottom Hulls

Advantage: This planing hull has a shallow draft, which is good for fishing in small lakes and rivers.
Disadvantage:  Rides roughly in choppy waters.
 flat bottom hull  
                flat bottom hull                   
flat bottom hull  plan

Flat bottom, Flared Sides, Double-ended

The Chama Jon Boat Flat bottom, square bow
example of flat bottom hull

Round Bilge Hulls

 Advantage: This typical displacement hull moves easily through the water even at slow speeds.
Disadvantage:  Has a tendency to roll unless it has a deep keel or stabilizers.

Generally for this types of hulls these vessels are rounded and don't usually have any chines or corners.
They can be round-bilged, soft-chined or molded. Examples are the s-bottom hull, semi-round bilge and round bilge.

 round bilge hull    

 round bilge hull   

    round bilge hull      
  round bilge hull

V Bottom Hulls

 Advantage: This planing hull gives a smoother ride than a flat bottom hull in rough water.
Disadvantage: Takes more power to move at the same speed as flat bottom hulls. May roll or bank in sharp turns.

The "V"-bottom boat is probably the most common hull design. Most manufacturers of boats built today use modifications of this design. This design offers a good ride in rough water as the pointed bow slices forward and the "V"-shaped bottom softens the up-and-down movement of the boat. The degree of the angle of the "V" is called "deadrise." As the "V" shape extends to the back of the boat, it usually flattens out until it all but disappears at the transom. Some "V"-bottom boats have a flat surface at the very bottom called a "pad." This pad allows a little more planing surface and at the sacrifice of a little softness in the ride, but this addition increases top speed.
v bottom hull
             v bottom hull           

   v bottom hull with strakes

v bottom hull with super high speed performance

v bottom hull

Planning Hulls

Boats with planing hulls are designed to rise up and glide on top of the water when enough power is supplied. These boats may operate like displacement hulls when at rest or at slow speeds but climb towards the surface of the water as they move faster.

How Planing Hulls Operate

Planing hull performing like a displacement hull Displacement Mode—A planing hull, when operated at very slow speeds, will cut through the water like a displacement hull.
Planing hull in plowing mode Plowing Mode—As speed increases, a planing hull will have a raised bow, reducing the operator's vision and throwing a very large wake. Avoid maintaining a speed that puts your boat in plowing mode.
Planing hull in planing mode Planing Mode—Your boat is in planing mode when enough power is applied so that the hull glides on top of the water. Different boats reach planing mode at different speeds.

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