Day 1 - July 7th Inspiration and Research
Total time - 2 Hours
After taking some inspiration from a friend creating their own RC Fan Boat, I wanted to dip my toes into the RC world through making my own. I figured that an RC Boat would be a relatively easier, yet still challenging, project to start working with RC and making my own things. In the future, I will hope to make a custom 5" FPV Drone as I enjoy flying my current TinyWhoop.
I used to have a fast RC Speedboat and would take it out to the lake to drive around whenever I could. I would like to try and bring this boat as I used to and try it out.
After looking at my friends fan boat, I wanted to try and challenge myself with a water prop boat. I began by looking online at videos and forums of the design of a boat. I watched many videos of boat builds and design. This site of another creator's build process helped me form an idea of the physics behind a good RC boat with CoM. It also helped me in deciding my hull shape to be a displacement/deep V single hull. I decided this hull shape as it would be easiest to design and because it is similar to the boat I used to have.
To propel the boat, I decided I will integrate a water jet/boat intake into the hull. This allows for a more compact boat and allows the prop to be protected. I looked at various designs of water jets before picking one to design my boat around. With the general boat design in mind, I am ready to begin design.
Day 2-3 - July 8-9 Picking Parts and Designing Hull
Total Time - 8 Hours
Today, I began by choosing the components of my build. ELRS Reciever - Could be used with my Radiomaster Pocket ESC - Good reviews, reccomended to me, has the specs I need For me, the hardest part was picking the motor and battery. These 2 had to work together so picking them took some time. I wanted to minimize weight and maintain a slim boat. I decided a 3S lipo battery was unneccesary weight, so decided to use 2S. Runtime is not a huge factor for me, so I decided to pick a lower end mAh rating. I also wanted to keep the temperature low in the hull to prevent overheating. I spent a long time looking for light, low mAh 2S battery with an XT60 Connector to work with my ESC. I eventally managed to find this battery. I also spent a long time looking for a small diameter motor that worked with my battery and ESC. I wanted to have a motor with low kV to keep the temperature as low as I could. After a long time searching, I eventually found this 2280kV 2040 Brushless Inrunner Motor. With this in mind, I created a basic layout of the components in the hull.
I struggled greatly trying to make the cap for the boat. Keeping water out is crucial. I started with trying to use an o ring seal.
After finding out that I'd have to waste $12 on 10 feet seal and $7 on 2 inserts, I decided not to go for that. My next idea was to create a slide on cap.
I did not really trust this and couldn't find a way to secure this. Finally I tried to go back to my orignial idea, instead using a TPU gasket a few layers tall going around the top. I then added screw holes into the plastic and added a tab in the front to keep the cap secured.
I integrated the water jet with a hole on the bottom and back, and adding a place where I can add my motor and servo.
The servo will lay horizontal and attach to the jet outlet via a paperclip. I made many mistakes and changes throughout the day, making the design process take a long time.
Day 3-4 - July 10-11 Design Finishing Touches
Time Spent: 4 hours
Throughout these past couple days, I spent lots of time to finalize the layout for my components and modeled them on the CAD to try and get a favorable center of mass while keeping the wiring in mind. This image from the ESC page shows the wiring between each of the components:
I modeled the servo mount off of the motor mount above the jet. To keep these components in place and allow for easier printing on my 3D Printer, I created small compartments with chamfers to remove the need for supports. I found some double sided VHB Tape to keep them in place. I decided to use a 3mm prop shaft and eventually found a coupling for the motor and prop shaft.
Finially, I found a set of screws on amazon that had each type that I needed and a JST Connector converter to charge my battery. I tidied my list of components/parts into a BOM on google sheets.
Now that the design of the boat is done, I will ship it to hackclub and hope for an approval to make it!