The Penny Boat

The Penny Boat

By Ashwin C, Gabriel D, and Adam T

We believe that our penny boat could be the most efficient way to build a buoyant boat,and can also withstand the weight of many pennies without tipping over or sinking.

We started off with a boat that could hold pennies stacked really high but with a small boat as the base. We measured the diameter of a penny, and then made the tube 1mm bigger than the diameter of the penny. The problem was, it tipped due to the weight of the pennies. It was top heavy, so it took less shaking for it to tip over. So we had to move on to another idea with a larger boat base.

With our second boat, we wanted to keep the element of the pennies being held by a series of tubes, but we had to make it float better so it would not tip over. So what we did was we made the boat much bigger, and instead of tubes made out of a thin layer of plastic, we created holes going into the boat depthwise to be the tubes that would sustain the pennies. It floats extremely well, and will not tip over unless put in the water upside down. After printing this, we realized that we did not have the 2cm hole that is required for the competition.

So then we finalized this design. The only difference between this and the previous one is we have a hole through it (as required) and the tubes for the pennies are spaced out more to make space for the hole in the center. It has eight slots to hold as many pennies as possible and it is made so it is positively buoyant, and the hole through it to fit the requirements of the project. But when we tested this design, we felt that it did not hold enough pennies. So we decided to redesign it one more time so that it would hold as many as we could.

For this last design, we wanted to make it as large as it could possibly be, so it could hold as many pennies as possible. The dimensions were 100 by 100, so we did a 99mm by 99mm semi circle. Our first print was not extremely tall, but was designed to be buoyant while holding as many pennies as possible. We put our 2 cm hole near the bottom, so that water would not infiltrate at the top. We also made sure that there were no holes that poked out of the surface of the semicircle, because if there were holes, water would go into the penny slots and it would become much heavier on one side, and therefore tip over.

We printed a second version that was 99mm tall, to see if it would hold more pennies. As shown in the picture below, it has the capacity for many, many more pennies. However, we had to test both versions of this design to see which one would hold more. The reason that we weren’t sure which one would hold more is because the one that is super tall will be much less buoyant. If it tips over, we can only count however many pennies it held before it tipped. When we tested the two, we found that the shorter one worked. It held 64 pennies on the first test. We decided to keep testing it again and again so that we could get the best result.