Don’t Mind If I Ski-Do

There is an age-old tradition among hackers of just making it yourself. Whether the real thing is too expensive or you think you can make a better one, the itch strikes, and it can quickly spread. [Homemade Madness] has quite the itch as he builds his own jetski.

What is a jetski but a boat with a shell on top? In an earlier video, he created a boat out of plywood and, after the usual steps of fiberglass and sealing, was proud to float around in his relatively normal-looking boat. But now that he had a working bottom, it was time to return to CAD. He printed out templates for all various shapes he would need, each labeled with a different designator, and glued them to the plywood. No fancy CNC here, just a steady hand and a jigsaw. We love the professional build instructions he compiled for himself that detail in LEGO-like quality exactly how each piece slots into where and in what order to do them. In addition to the top layer of the jetski, he also designed a stand for the boat to rest on while he made it, which is just going the extra mile. A ceiling-mounted winch made it easy to lift the ship into position. Next, he connected all the various framing pieces with PU glue. Thin plywood acted as cladding on top of the skeleton. Filling, sanding, and fiberglass overlaid the structure, making it waterproof. More sanding and some primer later, and it was ready for another water test.

He designed a version with an outboard motor, but he’s trying to build one with a built-in jet drive. So we’re looking forward to seeing the next step and him flying around on his custom watercraft. But what he has already done is quite impressive. If you’re looking for something a little smaller to pull you around the water, why not take a look at this little 3d printed tug boat? Video after the break.

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The Little 3D-Printed Tugboat That Could

If you’ve ever spent time watching the goings-on at a seaport, you must have seen tugboats at work: those little boats that push, pull and nudge enormous cargo ships through tight corners in the harbor. They manage to do that thanks to hugely powerful engines sitting inside their relatively small hulls; their power-to-tonnage ratio can be ten times that of most commercial ships.

One hardware hacker who enjoys building similarly-overpowered machinery is [Luis Marx], and it might not come as a surprise that his latest project is an actual tugboat. Living on the shores of Lake Constance in southern Germany, [Luis] likes to spend time on the water, but got fed up with the chore of paddling. Local regulations restrict the use of outboard motors but allow the use of R/C model boats; therefore, building an R/C tugboat to move yourself around the lake should be perfectly legal.

While we’re not sure if the Lake Constance Police will follow the same reasoning, [Luis]’s model tugboat is a wonderful piece of engineering. With a design inspired by 3DBenchy, the standard 3D printer benchmark that probably anyone with a 3D printer has printed at some point, it took about 30 hours to create the parts plus a generous helping of epoxy resin to make it all waterproof. A beefy lithium-ion battery pack drives two brush-less DC motors designed for racing drones, which together can put out nearly one kilowatt of power.

That, unfortunately, turned out to be way more than the little boat could handle: any attempt at using it simply caused it to leap out of the water and land on its back. Setting the motor controller to around 50% made it much more controllable, yet still strong enough to move [Luis] around on his standup paddle board. The boat is controlled through a custom-made handheld R/C controller that communicates with the ESP8266 inside the boat through WiFi. With no rudder, left-right control is effected by simply reducing the power of one motor by half.

A fully-charged battery pack provides enough juice for about 40 minutes of tugging, so it’s probably a good idea to bring along paddles in any case. Unless, of course, you’ve also got a solar-powered autonomous tugboat ready to come to your rescue.

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A Cow-Powered Human Centrifuge

Spoiler alert: group of fun-loving French folks build an animal-or-human-powered merry-go-round that spins fast enough to fling all takers into the lake (YouTube, embedded below). Actually, that’s basically it. The surprise is ruined, but you probably want to check out the video anyway, because it looks like a ton of fun.

Granted, you may not have a well-stocked metal shop or a team of oxen up by the lake wherever you live, but there are certainly details in the video that will survive in translation. Basically, the team took the axle off of a junked car, attached it to a pole in the middle of the lake, made a large wooden drive wheel, and wrapped an infinite length of rope around it.

[Charles] from [Mad Cow] wrote us that there was about a 10:1 ratio between the drive wheel and the arms of the people-flinger. So if the cattle were pulling at 3 km/h, the human angular velocity was a brisk 30 km/h! Then it’s just a matter of convincing a team of cows, or a team of soccer players (?), to put their backs into it.

The [Mad Cow] crew seems to have more than their fair share of engineering dangerous fun up at their summer hideaway: check out their human crossbow that we featured a few years back.

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Build A Beach Winch For Wakeboarding

beachwinching itself is a hack of common wakeboarding. No waves? hrm... lets hack something together.

Here’s a build log forĀ  a nice beach winch for your next trip out to go beachwinching. Beachwinching is when you use a fast winch on shore to pull you in, allowing you to wakeboard, wakeskate, or water skii without the need of waves or a boat or jet ski to pull you along. While there’s nothing amazingly groundbreaking here, we do love a nicely documented build log. We think a remote way to initialize the pull would be nice too.

You can catch an example video of beachwinching after the break

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