1. Summary & Printable Handouts

Electric Motorboat Drag Racing is a culminating high school physics project to apply and bring to
life the California Content Standards for Physics. Students design, build, and race model-sized electric motorboats.

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Further Investigations:

• Which battery(ies) provides the best performance?
• Which motor provides the best performance?
• Which hull design provides the best performance?
• Which propeller provides the best performance?
• Which propeller angle and shaft length provides the best performance?
• Which material and/or coating provides the best performance?
• Which selections are the most cost effective?

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2. California Physics Standards

The project gives students hands-on experience with these CA Content Standards for Physics*:

• 1b. Students know that when forces are balanced, no acceleration occurs; thus an object
  continues to move at a constant speed or stays at rest (Newton¡¯s first law). ¡°A push or a pull (force) needs to be applied to make an object accelerate.¡±
   

• 5a. Students know how to predict the voltage or current in simple direct current (DC) electric circuits constructed from batteries, wires, resistors, and capacitors.
   

• I&E 1c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.

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3. Attainment of Standards

The student demonstrates his or her attainment of the selected standards in the following ways.

For 1b:

• Student designs his boat to have an unbalanced force accelerate it forward from rest.

• Student increases the forward force from the motor by improving its angle or battery power.

• Student decreases the resistance forces of friction on or within the boat.

• Student reduces the mass of the boat to increase its acceleration from the same net force.

• Student accurately completes page 1 of the Physics Worksheet.

For 5a:

• Student designs his boat to have a properly wired circuit that he can turn on and off.

• Student increases the motor's force by using fresh, more or higher voltage batteries.

• Student fixes a dead motor or malfunctioning circuit by checking and fixing wire connections.

• Student accurately completes page 2 of the Physics Worksheet.

For I&E 1c:

• Student notices inconsistent boat performance and communicates the causes or reasons.

• Student adjusts or changes the boat design, shape, or materials to improve or fix it.

• Student adjusts or changes the boat's batteries, wires, or motor to improve or fix it.

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4. Materials Needed: Rain Gutters, Water & Stopwatches

For about $40, four 3-meter plastic rain gutters (shop for 10ft vinyl gutters with a 4¡± to 5¡± width), two connectors, and four end caps (seen in starting photo and video clips) can be purchased from a home improvement store (find a local store here). Use rain gutters with a symmetric U-shaped cross-section, not "K" type gutters. Typical rain gutters are 3 meters long, so two need to be connected in line to make each 5-meter drag racing lane.

The four rain gutters will require about 20 gallons to fill, so 5-gallon jugs, buckets, or a hose are recommended for use throughout the competition. Three stopwatches are also recommended to time the races.

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5. Project Timeline

The project can be assigned during 1 class period using this website and discussion (and the Project Rules printout). No other class time needs to be given for working on the project. Students should be given approximately 6 weeks to complete the project at home. It is important students begin looking for materials right away, especially propellers. You may plan one or more days after school for boats to be tested.

Once the boats are due, grading all the boats by inspection and timing them for qualifying 5 meter runs will take about one class period (use the Grade Sheet). Additional races and the drag racing tournament will take about 1 additional class period (use the Tournament Tree). After the drag racing tournament, you may use 1 to 2 class periods to complete the Physics Worksheet.

If you have multiple classes, plan for a final tournament with the fastest boats. The final tournament is a great opportunity to invite the school newspaper, yearbook, and community newspaper. Have awards, a perpetual plaque, and/or give extra credit to the fastest boats in the final tournament.

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6. Rain Gutter Setup

Connect two rain gutters in line to make one 6 meter long drag racing lane. Using a permanent marker, mark each lane so it has a starting line and finishing line 5.0 meters apart with a half-meter space at each end (see starting photo). This provides visible starting and finishing lines, 5.0 meters apart, with space before for a boat to be released (start zone) and space after for a boat to be caught (stop zone).

The drag racing lanes should be setup side by side about a fifth of a meter apart on level concrete, such as a level sidewalk (see photos & video clips). A typical drag racing lane requires about 10 gallons to fill, so use 5-gallon jugs, buckets, or a hose to fill and re-fill them during the races as necessary. To level the lanes and water, you can insert folded newspaper or thin boards under lower sections of each rain gutter.  Fill lanes uniformly to the top (see photo).

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7. Officiating the Tournament

Before the tournament (class): 1) print the Grade Sheet and Tournament Tree, 2) setup the rain gutters and have water available to re-fill them, and 3) get stopwatches to time the boats. The teacher should time the winning boats to assure they are placed accurately in the tournament tree.

First, the boats must be inspected and attempt the distance to earn a grade. Use the Grade Sheet to check & record the following information: 1) student names written on or attached to the boat, 2) proper materials (no manufactured toy boat body), 3) boat size (length<35cm and width<9cm), 4) proper batteries (one 9V or up to six D, C, AA, or AAA), 5) only one or more electric motors to power the boat, 6) the number of meters the boat propelled itself at one time, and 7) the time the boat needed to complete the 5 meter distance. The boat must meet all of the rules and propel itself the complete 5 meters at one time to qualify for competition.

Second, start the competition, but not the tournament. Allow every qualified boat to race at least once and enforce fair-racing practices. The teacher starts the race with "Ready, Set, Go". The teacher times the race from "Go" to the moment the finish line is broken by the winning boat. The teacher records the times for the boats on the Grade Sheet. Keep track of the fastest eight boats and let students know what time they have to beat to be in the fastest eight. Once you have the fastest eight boats, you are ready to start the class tournament.

Third, use the Tournament Tree to pair up the fastest eight boats (1st vs. 8th, 2nd vs. 7th, 3rd vs. 6th, and 4th vs. 5th).   If a boat breaks and cannot continue in time, you may give its opponent a win or replace it with the next fastest boat not in the tournament. Once you have the fastest four boats, pair them up (1st vs. 4th, 2nd vs. 3rd) based on their current winning times. Have the two losing boats compete in the drag race for 3rd and 4th place and the two winning boats compete in the drag race for 1st and 2nd place in the class. Time permitting, announce and make these final matches the best two out of three to win. Don't forget to congratulate the winners! If time permits and it is safe, your students might want to try some boat jousting.

If you have multiple classes, choose the fastest eight and arrange for a final tournament. The final tournament is a great opportunity to invite the school newspaper, yearbook, and community newspaper. Have awards, a perpetual plaque, and/or give extra credit to the groups with the fastest boats in the final tournament.

Email rbarry@electricboatproject.com feedback, questions, comments, pictures and times!

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