I have built a catamaran. It is called the FLOATBOAT 2000. I was building it on my DMP server while my friend messed around, and I didn't seriously expect it to work. But work it did! I built a boat capable of at least 135 m/s (486 km/h), and I haven't even tested it to it's maximum speed yet. It remains controllable (but unmaneuverable) throughout this time, although it lost several intakes and a rudder while I was trying to turn at that speed. At lower speeds (around 30 m/s) it is maneuverable even without the rudder I lost and it doesn't lose any intakes while turning. Getting to the water is handled by a large set of wheels, and it took a good 20 minutes to wheel the thing to the water. This is the only disadvantage of the FLOATBOAT so far. The FLOATBOAT itself is powered by two jet engines, and is steered by two below-water rudders and four above-water fins. The rudders underwater provide an advantage, or at least have some effect, as they seem to help with stability and when I lost the right one the craft started listing to the left. Here's the FLOATBOAT with wheeling gear on. Confirmation of speed The FLOATBOAT kinda digs into the water at high speed. While worrying, it doesn't actually harm the craft. Top down at high speed The FLOATBOAT while stopped. Note how the bow rises out of the water. It's top heavy. At low speed. Splashes stop at high speed for some reason. Showing off the surviving rudder More at low speed The FLOATBOAT's maiden voyage stopped here. I was testing what would happen if I tried to use the engines on land, and while sliding along fine for a while it eventually did a backflip and landed in the water after shedding engines and cockpit. The cockpit survived. Craft file here: https://www.dropbox.com/s/z3mb9hfcozzgsha/FLOATBOAT%202000.craft?dl=0 Feel free to make better land gear or even a dropship to get it to the water, as it currently takes FAR too long to get it to the sea. UPDATE: Better ground rig added, as it is now capable of speeds up to 80 m/s on land. UPDATE DOWNLOAD: https://www.dropbox.com/s/13012qc4ur6an9a/FLOATBOAT%204000.craft?dl=0 New ground rig