||This kit manufactured by Robbe was a childhood dream of mine; never realized until adulthood... I admit to having taking a bit of a shortcut here: I got the boat already built on e-bay. The boat was in reasonable condition when I received it, but I did invest quite a bit of time into a complete restoration and upgrade.
||The boat is about 1.2m long and 9kg in weight. It is quite substantial, but still fits into the trunk of the car. The scale is 1:24 - it's far from an exact replica of the original, though.
The boat is powered by two 600-class DC motors. I never quite figured the exact type and model of the motors, but they seem quite happy running on 12V. The original propellers were rather small affairs, generating a lot of froth but not moving the boat forward much. They were replaced with proper 35mm brass propellers.
||The whole boat is powered by a single 12V 7.5AH lead acid battery. The boat came with a single speed controller that was on its last leg. After my upgrade, each motor now has its independent water-cooled electronic speed controller, each on a separate channel on the remote control. This allows complex maneuvering such as turning on the spot.
All power on the boat is derived from the 12V using linear regulators (LM3805 / LM3806). I use seperate regulators for the RC system, the Arduino and monitor servos to avoid overheating, as the servos in particular can draw significant current.
||Besides the usual RC components, the boat features custom electronics based on an Arduino. The Arduino controls all miniature lamps, drives the pump with variable speed and controls the servos for the monitors, shutting them down when not needed to safe power. The Arduino also measures battery voltage, giving flashing the lights to signal when the battery is depleted.
During the early stages of development, the Arduino also controlled two MOS-FET H-bridges for speed control. However, handling an inductive load with stall currents beyond 40A was slightly outside my comfort zone (I'm a computer scientist, not an EE); so while they worked, I opted for commercial speed controllers instead.
More details here.
||All three monitors are fully working. They turn about 270 degree and squirt water about 2-3m. Lights can be turned on individually.
The boat is seriously fast when going at full speed. This is of course cool. However, with its substantial weight, it generates massive wakes as well, and unless the pond is very calm, one easily spills a lot of water onto deck. The deck, however, is not fully water tight especially around the water pumps. After an intensive day on the pond, a lot of water ends up inside the hull, suggesting the addition of a bilge pump...
The horn sounds horrible - some microcontoller-based sound engine is planned for some long winter nights...