As of now, this project has bumped into a minor problem: the radio transmission system has stopped working. Data is being transmitted via the XBee modules, but the ATMegas are not understanding each other. I will have to look into the code (which I will post soon) and check if the transmitter and receiver code both implement the protocol correctly. While I am at it, I should redo the protocol: it's quite bloated and has lag issues. The XBees are sending and receiving; I have verified this using an XBee Explorer from SparkFun.
While this is being fixed, I still have to work on the boat final assembly. The foam base is ready to be affixed to the electronics platform: a wooden board running lengthwise across the foam. This will be assembled using a "glue and screw" technique for the best adhesion possible. I'm using some small plastic food containers from the dollar store to hold the electronics and keep them dry. This is especially important for the Li-Po battery. Two separate containers are used: one for the battery, and one for the receiver. The battery is relatively heavy, and this must be placed in the center of the boat to prevent tipping. I also have to find room for the receiver container alongside that (though it is light, placing it on the side would still tip the boat a bit and potentially steer the boat in one direction), and space is tight underneath the brace for the propeller-pole.
After this is finished, I will be able to finally test it and start adding cool features (expansion port for sensors?).