Analytic Essay



 Background Info


Lab Report 


 Method & Materials






If we were to redesign the experiment we would change a few things. The most necessary change would have to be well attached propellers. Our propellers were decently glued, but still fell off after being in the water for about 30 minutes. This caused delays in our recording of speed. Also we would want the sub to travel faster.

If we took the sub to much deeper water we would have many problems. The sub can barely take the pressure applied from 11 feet of depth (we know this because Ian's sub was having problems at about 13 feet), so you can imagine what would happen in deeper water. At 11 feet , 1 and 1/3 atmospheres, it was under 19.6 pounds per square inch of pressure. Also, if the sub went much deeper than 11 feet we would not be able to see it from the surface. Several problems could arise from that. this could easily be fixed, but the power cords that are attached to the sub are only 11 feet long. So the sub physically can't go any further, in any direction, at the moment.

If the wires were longer, tests could be performed at multiple distances. For example, tests on how long it takes to travel 11 feet and how long it takes to travel 22 feet. That way it would show if the sub slows down after traveling a certain distance.

We learned that underwater engineering can be frustrating. Motors fail, batteries die, and propellers fall off. It takes patience and hard work to be successful. We also learned , like Tim Taylor says on Home Improvement, "Measure twice cut once, not measure once cut twice."

All times below are in seconds.

The sub travels the fastest straight, averages 11 feet in 8.94 seconds. The sub averages 11 feet in 13.38 seconds, ascending. Descending, it averages 11 feet in 14.54 seconds. A 360 degree turn to the left takes the sub 15.66 seconds, on average. A 360 degree turn to the right takes the sub about 176.43 seconds, on average. Traveling backwards takes the sub the longest, it averages 18.73 seconds. These results show that the sub travels at a rate of about 1.23 feet per second going forward.

One of the scientific principles we learned about was buoyancy. What we did was cut large pvc floating devices into lengths of about ten inches. We then placed caps on both ends to prevent leaking. After that, we strapped them to the frame of the boat. This gave the boat positive buoyancy. Next we added negative buoyancy. To do this we connected mesh wire to the bottom of the frame. With that there, we were able to add lead fishing weights to supply negative buoyancy. The floats and weights provided neutral buoyancy for the craft. This allowed the sub to remain level while underwater, not tilting to one side or the other, and not move unless pushed by the thrusters or a current in the water.

The percent of error was low because our results were very consistent. (As you can see on our lab report page.) The percent of error for each direction was under 10%. After getting the times and average for doing a full turn turn to the right we found out that the percent error was 2.7%. Then, we found that the percent error for going down was 2.8%. After that, we learned that the percent error for going backwards was 3.8%. Next, the percent error we received for doing a full turn to the left was 4.2%. Then we had to figure out the percent error for going up which was 5.3%. Last, we got the percent error for going straight which was 9.7%, barely making the 10% mark.

We had a great time building and testing this sub. We recommend this project to anybody that is interested in D.E.E.P.


Day 1 log-Monday, April 14

Today we planned out how and where we would get our tools and parts needed for the project. The order in which we will construct has been set, and we will be able to begin during the next class. The teachers met with us to discuss our project proposal and overall progress. We are right on schedule

Day 2-Thursday April 24
Today we began the construction of the sub. We completed most of it. David built all the thrusters and attached the power cords to them. Jeff built the frame. He "Measured twice and cut once."

Day 3-Monday April 28

Today we finished off the construction of the project. We glued the propellers on, not well enough as we found out later.

Day 4-Tuesday April 29

Today was the field trip to Long Beach. At the big pool there, we tested the sub as much as we could. Unfortunately, the propellers kept falling off, so we had to postpone the rest of the testing for the next period at school.

Day 5-Tuesday May 6

Today we had the propellers fastened thanks to the work Jeff and I did at home. We were able to complete our testing in the school pool. We also wrote our analytic essay.