UPDATE 2: I've added three new mounts which will allow you to mount brushless outrunners on a boat. On is a simple transom mount while the others use engine nacelles. The transom mount would be ideal for a boat that draws more water. With mine, the props weren't submerged enough. The smaller nacelle works well, but has a maximum velocity where the water will be split aside by the nacelle and less will reach the prop, limiting the max speed. The long nacelle hasn't been tested but may correct the issue. UPDATE 1: These motors have proved to be too weak to propel this boat at high speed. Even with four I am only getting about 3 mph. I'm going to bite the bullet and buy brushless motors. I will be adding the new mounts for standard brushless motors within a week. These parts were created for an engineering project where a boat must transport an orange through a course. The props and mounts are for the 9-18v high speed DC motor sold by RadioShack. The props will fit any 2.3mm shaft though. I also included a mirrored version of the prop since I used counter rotating props on one side of the boat. The parts were made in Solidworks and those files are included. Note: Solidworks is a Y-axis up modeling program, so you may need to rotate the parts to their correct orientation to print without support. Rudder: This rudder and its mount were designed for a hull that is 50mm thick. The rudder and mount are printed without support with 30% infill and use snap fit hinges. The hole on the servo arm is tiny will probably need to be drilled out to fit the push rod. I used two part epoxy to glue the mount to the boat. Motors: The props must be printed with support at 50% infill. Only the bottom edge of the blades should be supported so it is easy to remove. You will need a small drill bit to remove the support from the drive shaft hole. The props are simply pressure fit onto the shaft. Therefore, they may fly off if you attempt to use them for reverse thrust. Motor Mount: Use with 9-18v high speed DC motor from RadioShack. These were the only motors I could source locally and that was a requirement of my project. Print the mount at 50% infill and glue with two part epoxy to the flat bottom of your hull. Loop a hose clamp or two zip ties through the hole in the mount to secure the motors.