Wake Free Boats

Project #1Marine Transportation

ObjectivesAfter completing this activity, students will be able to: State the roles aerodynamics plays in boat

designs. Demonstrate an understanding of how and why

aerodynamics is important in boat design. State what a wake is and how to increase or

decrease it. State different designs a boat can have State the processes involved in creating an wake

free boat Create an Wake Free Boat that makes the smallest

amount of wake while being pulled across the entire distance of the trough

Content

Boats and ships range in their designs because of their uses. For example, some ships simply drive through icy water, breaking up the ice so other ships can make it through. Where other boats can’t drive through the water so they drive over the water such as swamp boats and pontoon boats. Lets see how creative you are in designing your own wake free boat.

Aerodynamics in Boats What role does Aerodynamics play in boat

design?

Answer:

Like most land vehicles aerodynamics is a huge factor in designing boats. Some boats are made for speed while others are made to go over swampy areas. The most typical ways to make a boat aerodynamic is to start with a v-hull. Depending on the angle of the hull the boat can have a large wake

Aerodynamics in Boat Design

Aerodynamics is the result of water friction on the boat hull. Also the exterior finish of the hull design will determine how fast your boat will go. The smoother the finish the less friction along with a creative hull design results in a fast boat. The way the water comes off the back of the boat also determines the wake as well as speed.

What is Aerodynamics?

Answer:

“Aerodynamics" is the study of how air flows around, over, and under an object

What is a Wake? A wake is wave caused by the water curling

once it has passed across the boat hull. The more area exposed to water and the speed you drive your boat will determine how large or small of a wake you have. Wake boarders use these large wakes to do amazing tricks. Wake boats use large sand bags in the back of the boat to weigh it down so more area of the boat is exposed to the water. Gator boats in florida don’t have much wake at all because of the marshes they have to drive over.

What are different boat hull designs?

There are many different boat hull designs:

What are different boat hull designs?

Flat-bottom boats The one thing you can say about flat-bottom boats is that with

their large bottom area, the boat is very stable in calm weather. Characteristically, however, the flat, broad bow area creates a rough ride. These boats are usually limited to low horsepower motors because they don't handle well at high speed. Flat-bottom boats are greatly suited for fishing in skinny water from the Susquehanna River to the Florida Keys, where a very shallow draft is a must.

Early in our nautical history, boats were powered by wind or by hand-stroked oars. Early boat designers found that boats went faster, and were easier to steer, if the bow was pointed. They also soon discovered that by lowering the center of gravity, the high sail masts had better balance, and usually kept the boat upright even in bad weather.

What are different boat hull designs?

What are different boat hull designs?

Displacment, planing hulls These early boats were constructed with

"displacement" hulls. This means that the hull would push through or cruise through the water. The proper propeller for a displacement hull is one with a lower pitch when powered by an outboard or stern drive. With the advent of mechanical power came boats with "planing" hulls, which lift the boat partially out of the water to skim on the surface. Today, it's sometimes difficult to tell the difference between the two, but there are slight differences. Propellers on boats with planing hulls often are not fully submerged, so they need to provide holding ability as well as higher pitch and rake, because of higher top-end speeds.

What are different boat hull designs?

What are different boat hull designs?

Round-bottom hull,"V" bottoms 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.

What are different boat hull designs?

What are different boat hull designs?

Tri-hull, tunnel hull There are many boats in Pennsylvania

waters that are a distinct modification of the "V"-bottom that are called tri-hulls and cathedral hulls. The tri-hull boat is the traditional "V" hull with additional outside hulls. This design is more stable than the "V"-bottom at rest, but it gives a rougher ride in choppy water because of the increased surface at the bow.

What are different boat hull designs?

What are different boat hull designs?

Pontoon boat Very popular in the Keystone State are

pontoon boats. And just as the name implies, the pontoon, or deck boat, is a flat, raised deck supported with two outer hulls (pontoons) that are usually constructed of aluminum. These boats combine a lot of features of other boats. They ride very dry because the deck is raised above the floats. They are stable, and with the transom mounted to the underside of the deck, they are easy to maneuver with an outboard motor.

Materials Scrap wood Pine Plastic wheels Metal Rod 1/8” diameter Wood Glue/ Hot Glue Supplies from trays Machines and tools

Challenge Your grade for part 1 depends on how

close to your Printed Picture you made your Accuracy Car. The closer it resembles your pictures, the better your grade will be. The more changes you make or extra pieces you add the lower your grade will be if they take away from the overall shape and design. Details are encouraged but keep them realistic.

ChallengePart 2 deals with the actual testing of the vehicle. You will be at one end of the trough. Your boat will be connected to a string which in turn travels through a pulley system and then to a weight at the end. The weight will pull your boat through the trough. The object is to construct your boat so there is little to no wake behind your boat. Take into account the angle the boat will be pulled at. There are no partners on this project; each student must make their own vehicle.

Challenge

Your grade for part 3 is the boats when done cannot be smaller than 8” long x 3 ½” wide x 4” tall or larger than 10” long x 4 ½” wide x 5” tall. You will be automatically disqualified and receive a zero if it is smaller or larger in any or all of these dimensions. You also cannot add weight to slow your boat down or make your boat travel under the water. The design of the boat is up to you but must be one of the boat hull designs covered in the previous slides.

Challenge

Be creative on this project and a nice design and creative effort will only increase your grade. You must do all work in class unless I give you permission to take it home. Good luck

Procedures Select the your favorite boat design that

isn’t too challenging to make Research it on the computer finding

pictures or just draw it the best you can with a ruler and dimensions

Cut your pine wood, wood glue it together

Construct your boat Practice your boat as often as possible

making any changes needed

Evaluation Printed Pictures are a separate grade

worth 100 points There is a reflective worksheet that

counts as a separate grade of 100 points

See Attached Rubric Remember that there is no fooling

around in the lab Always wear your safety glasses or you

will be removed from class

Evaluation Project stayed within the required

dimensions Project looks like printed or drawn

pictures with minimal changes Project made minimal wake and

traveled the entire distance of the trough

Student shows above average effort Student shows above average safety

skills

100 Points

Evaluation Project stayed within the required

dimensions Project looks like printed or drawn

pictures with moderate changes Project made moderate wake and

traveled the entire distance of the trough

Student shows above average effort Student shows above average safety

skills

75 points

Evaluation Project stayed within the

required dimensions Project looks like printed or

drawn pictures with very noticable changes

Project made excessive wake and traveled the entire distance of the trough

Student shows above average effort

Student shows above average safety skills

50 points

Evaluation Project did not stay within the

required dimensions Project does not look like printed

or drawn pictures Project made an extreme wake

and/or traveled the entire distance of the trough

Student showed no effort Student showed no safety skills

0 points