Pop-pop boats are a neat little science teaching tool that many children end up playing with at some point or other. They’re normally sized to float around a sink or bathtub. [Steve Mould] recently got the opportunity to board a much larger example, sized for an actual human passenger.
The boat belongs to the The AHHAA Science Center in Estonia, along with a smaller model about half the size. Both are fired by propane gas burners to give them some real heat output into the water tank, far beyond what you’d get from little tea light candles. In the case of the larger boat, it uses a series of valves to allow the tank to be filled with water while the rear thrust pipes are closed.
At the larger scale, it’s more easy to visualize the flow out of the boat’s rear outlets. It’s by no means a fast way to get around on the water, with a top speed somewhat less than walking pace. It’s also very loud. Regardless, it’s amusing to see the pop-pop engine work even when scaled up to full size.
If you’re looking for an in-depth explanation of how pop-pop boats work, [Steve Mould] has covered that previously. Video after the break.
The two best days in a boat owner’s life are the day they buy it, and the day they sell it. At least, that’s the common saying among people who actually spend money to buy a boat. [saveitforparts], on the other hand, looks like he’s going to have many more great days on this boat than that since he cobbled it together nearly for free, and he won’t even need to purchase any fuel for it since it runs on solar power.
The build starts with [saveitforparts] heading out to a literal pile of boats in his yard, unearthing an old single-person sailboat, and then fixing the major problems with its hull. With a new coat of red paint, the focus turns to the drivetrain. Propulsion is handled by an electric trolling motor found at an auction for $8 and is powered by an off-the-shelf battery bank provided by a sponsor of his channel. A pair of solar panels (which were traded for) fitted to outriggers keep the battery bank topped off, and there’s plenty of energy left over with this setup to charge drone batteries and other electronics while out on the lake.
[saveitforparts] reports that the single-passenger solar boat is remarkably stable on the water and fairly quick at full speed thanks to its light weight. He even hypothesizes that it could be fished from. The only thing not particularly stable was towing it to the lake, as the rough roads and permanently-attached solar panel outriggers weren’t particularly congruent with each other. If you’re looking for something similar to carry a few passengers, though, have a look at this much larger version.
Regular hulled boats are all well and good for rowing and all, but if you wanna go fast, you’ve gotta cut your draft. [RCLifeOn] built a hydroplane design that skims on the very surface of the water, and thus travels very quickly as a result.
The build came about as [RCLifeOn] has an upcoming race which he wishes to win with speed and finesse. To that end, he 3D printed an RC hydroplane, using spray paint and spackle to waterproof the parts. It’s a trimaran design, with the large central hull connected to two pontoons via carbon fiber rods. Propulsion is via a triple-motor fan setup on the rear of the boat.
The outer motors were initially used to steer the boat via variable thrust, which comes with zero drag penalty compared to a conventional rudder. However, they proved ineffective, and a servo driven rudder was used instead. Eventually, all three motors were reconfigured for forward thrust.
When it comes to reducing emissions from human sources, we’re at the point now where we need to take a broad-based approach. It’s not enough to simply make our cars more efficient, or start using cleaner power plants. We need to hit carbon zero, and thus everything has to change.
To that end, even recreational watercraft are going electric in this day and age. Several companies are developing motor-powered models that deliver all the fun without the emissions. But to do that, they’re taking to the air.
Nothing beats a day on the lake in a little boat with an outboard motor putt-putting along behind you. It’s great fun, if perhaps a little noisy with all that putting going on. And maybe that oily sheen on the water in your wake is not so nice. it could be that the fish are a little annoyed with your putting, too. Come to think of it, outboard motors are a bit of a problem.
Fortunately there’s a better way, like converting an old outboard motor to electric. It comes to us by way of [Anton], who happened upon the perfect donor platform — a 5-hp outboard by Crescent, sporting a glorious 1970s color scheme and a motor housing shell perfect for modding. He started by ripping the old engine and drivetrain out of the housing to make room for the BLDC motor and its driver. The motor was a project in itself; [Anton] rewound the original stator with much thicker wire and changed the coil configuration to milk as much torque as possible out of it. What started as a 180-kv motor ended up at 77 kv with much more copper and new Hall sensors for the controller. He also put a ton of effort into waterproofing the motor with epoxy resin. With a 3D-printed prop and a streamlined fairing, the new motor looks quite at home on the outboard. In fact, the whole thing barely looks customized at all — the speed control is even right on the tiller where you’d expect it.
The video below shows the build and a test run, plus an analysis of the problems encountered, chief of which is water intrusion. But as [Anton] rightly points out, that’s easily solved by reusing the original driveshaft and mounting the motor above the waterline, like this. Still, we like the look of this, and the idea of knocking around on the water nearly silently seems wonderful.
As 3D printers become more ubiquitous, the number of custom designs and styles of printers has skyrocketed. From different printing materials and technologies to the movements of the printing head, we’ve seen all kinds of different takes on these tools. But one thing that has been largely limited to commercial and industrial use has been large print sizes — leaving consumer level prints to be split into several pieces to fit together later. Not so with this giant 3D printer from [Ivan], though.
The design goals for this build are to print an entire boat that [Ivan] can captain himself, and additionally an entire go kart chassis in a single piece. It’s part of a contest between him and another YouTuber and as far as we can tell he’s well on his way to completing the challenge. The printer will be able to churn through 4 kg of filament per day, and has a printable volume of 1000x1000x1420 millimeters, or just shy of 1.5 cubic meters.
One of the downsides to healthy outdoor activities is all the exercise. Who would want to do that if you can build something to do the hard work for you? That seems to be the theme of [Bitluni]’s latest build, a simple (and hacky) propulsion system for a stand-up paddleboard.
After acquiring an inflatable stand-up paddleboard and trying it out a few times, [Bitluni] decided to skip the “stand up” and “paddle” parts. He designed and printed a very simple propeller, which he intended to power with a brushless motor and speed controller. In the process of drilling out the prop to fit the shaft, he realized he was overcomplicating things. So he decided to just use his battery-powered drill instead. For the shaft tube, he modified an old crutch by drilling a hole in the handle for the shaft and adding a duct with a bearing on the other end. He also attached a carabiner to the handle to fix it to the paddleboard.
A test at a lake showed that the propulsion system performed relatively well for a proof of concept but had some flaws. To submerge it properly, [Bitluni] had to sit on the rear of the paddleboard facing backward. If it was too close to the surface, it would suck air and lose thrust, or spray him and his drill with water. Of course, there is also the real risk of drowning his drill in the process.
Projects don’t need to be complex to be enjoyable, and you can often learn more by quickly creating a proof of concept instead of taking forever to come up with the “perfect” design.
If you want to see some more advanced water-borne projects, check out the waterjet-powered electric surfboards built by [RCLifeOn] and [Andrew W].