We’ll go out on a limb here and say that a large portion of Hackaday readers are also boat-builders. That’s a bold statement, but as the term applies to anyone who has built a boat, we’d argue that it encompasses anyone who’s run off a Benchy, the popular 3D printer test model. Among all you newfound mariners, certainly a significant number must have looked at their Benchy and wondered what a full-sized one would be like. Those daydreams of being captain of your ship may not have been realized, but [Dr. D-Flo] has made them a reality for himself with what he claims is the world’s largest Benchy. It floats, and carries him down the waterways of Tennessee in style!

The video below is long but has all the details. The three sections of the boat were printed in PETG on a printer with a one cubic meter build volume, and a few liberties had to be taken with the design to ensure it can be used as a real boat. The infill gaps are filled with expanding foam to provide extra buoyancy, and an aluminium plate is attached to the bottom for strength. The keel meanwhile is a 3D printed sectional mold filled with concrete. The cabin is printed in PETG again, and with the addition of controls and a solar powered trolling motor, the vessel is ready to go. Let’s face it, we all want a try!

There are a lot of things that get landfilled that have some marginal value, but generally if there’s not a huge amount of money to be made recycling things they won’t get recycled. It might not be surprising to most that this is true of almost all plastic, a substantial portion of glass, and even a lot of paper and metals, but what might come as a shock is that plenty of rechargeable lithium batteries are included in this list as well. It’s cheaper to build lithium batteries into one-time-use items like disposable vape pens and just throw them out after one (or less than one) charge cycle, but if you have some spare time these batteries are plenty useful.

[Chris Doel] found over a hundred disposable vape pens after a local music festival and collected them all to build into a battery powerful enough for an ebike. Granted, this involves a lot of work disassembling each vape which is full of some fairly toxic compounds and which also generally tend to have some sensitive electronics, but once each pen was disassembled the real work of building a battery gets going. He starts with testing each cell and charging them to the same voltage, grouping cells with similar internal resistances. From there he assembles them into a 48V pack with a battery management system and custom 3D printed cell holders to accommodate the wide range of cell sizes. A 3D printed enclosure with charge/discharge ports, a power switch, and a status display round out the build.

With the battery bank completed he straps it to his existing ebike and hits the trails, easily traveling 20 miles with barely any pedal input. These cells are only rated for 300 charge-discharge cycles which is on par for plenty of similar 18650 cells, making this an impressive build for essentially free materials minus the costs of filament, a few parts, and the sweat equity that went into sourcing the cells. If you want to take an ebike to the next level of low-cost, we’d recommend pairing this battery with the drivetrain from the Spin Cycle.\

Thanks to [Anton] for the tip!

https://www.youtube.com/watch?v=VcVp9T8f_W4

For a first try at an electric vehicle conversion we’re guessing that most would pick a small city car as a base vehicle, or perhaps a Kei van. Not [LiamTronix], who instead chose to do it with an old Ferguson tractor. It might not be the most promising of EV platforms, but as you can see in the video below, it results in a surprisingly practical agricultural vehicle.

A 1950s or 1960s tractor like the Ferguson usually has its engine as a structural member with the bellhousing taking the full strength of the machine and the front axle attached to the front of the block. Thus after he’s extracted the machine from its barn we see him parting engine and gearbox with plenty of support, as it’s a surprisingly hazardous process. These conversions rely upon making a precise plate to mount the motor perfectly in line with the input shaft. We see this process, plus that of making the splined coupler using the center of the old clutch plate. It’s been a while since we last did a clutch alignment, and seeing him using a 3D printed alignment tool we wish we’d had our printer back then.

The motor is surprisingly a DC unit, which he first tests with a 12 V car battery. We see the building of a hefty steel frame to take the place of the engine block in the structure, and then a battery pack that’s beautifully built. The final tractor at the end of the video still has a few additions before it’s finished, but it’s a usable machine we wouldn’t be ashamed to have for small round-the-farm tasks.

Surprisingly there haven’t been as many electric tractors on these pages as you’d expect, though we’ve seen some commercial ones.

In 2020 international shipping saw itself faced with new fuel regulations for cargo ships pertaining to low sulfur fuels (IMO2020). This reduced the emission of sulfur dioxide aerosols from these ships across the globe by about 80% practically overnight and resulting in perhaps the biggest unintentional geoengineering event since last century.

As detailed in a recent paper by [Tianle Yuan] et al. as published in Nature, by removing these aerosols from the Earth’s atmosphere, it also removed their cooling effect. Effectively this change seems to have both demonstrated the effect of solar engineering, as well as sped up the greenhouse effect through radiative forcing of around 0.2 Watt/m² of the global ocean.

The inadvertent effect of the pollution by these cargo ships appears to have been what is called marine cloud brightening (MCB), with the increased reflectivity of said clouds diminishing rapidly as these pollution controls came into effect. This was studied by the researchers using a combination of satellite observations and a chemical transport model, with the North Atlantic, the Caribbeans and South China Sea as the busiest shipping channels primarily affected.

Although the lesson one could draw from this is that we should put more ships on the oceans burning high-sulfur fuels, perhaps the better lesson is that MCB is a viable method to counteract global warming, assuming we can find a method to achieve it that doesn’t also increase acid rain and similar negative effects from pollution.

Featured image: Time series of global temperature anomaly since 1980. (Credit: Tianle Yuan et al., Nature Communications Earth Environment, 2024)

For those of us devoted to keeping an older vehicle on the road, the struggle is real. We know that at some point, a part will go bad and we’ll learn that it’s no longer available from the dealer or in the aftermarket, at least at a reasonable cost. We might get lucky and find a replacement at the boneyard, but if not — well, it was nice knowing ya, faithful chariot.

It doesn’t have to be that way, though, at least if the wonky part is one of the many computer modules found in most cars made in the last few decades. Sometimes they can be repaired, as with this engine control module from a Ford F350 pickup. Admittedly, [jeffescortlx] got pretty lucky with this module, which with its trio of obviously defective electrolytics practically diagnosed itself. He also had the advantage of the module’s mid-90s technology, which still relied heavily on through-hole parts, making the repair easier.

Unfortunately, his luck stopped there, as the caps had released the schmoo and corroded quite a few traces on the PCB. Complicating the repair was the conformal coating on everything, a common problem on any electronics used in rough environments. It took a bit of probing and poking to locate all the open traces, which included a mystery trace far away from any of the leaky caps. Magnet wire was used to repair the damaged traces, the caps were replaced with new ones, and everything got a fresh coat of brush-on conformal coating.

Simple though they may be, we really enjoy these successful vehicle module repairs because they give us hope that when the day eventually comes, we’ll stand a chance of being able to perform some repair heroics. And it’s nice to know that something as simple as fixing a dead dashboard cluster can keep a car out of the crusher.

What does it take to make decent tires for your projects? According to this 3D printed tire torture test, it’s actually pretty easy — it’s more a question of how well they work when you’re done.

For the test, [Excessive Overkill] made four different sets of shoes for his RC test vehicle. First up was a plain PLA wheel with a knobby tread, followed by an exact copy printed in ABS which he intended to coat with Flex Seal — yes, that Flex Seal. The idea here was to see how well the spray-on rubber compound would improve the performance of the wheel; ABS was used in the hopes that the Flex Seal solvents would partially dissolve the plastic and form a better bond. The next test subjects were a PLA wheel with a separately printed TPU tire, and a urethane tire molded directly to a PLA rim. That last one required a pretty complicated five-piece mold and some specialized urethane resin, but the results looked fantastic.

Non-destructive tests on the tires included an assessment of static friction by measuring the torque needed to start the tire rolling against a rough surface, plus a dynamic friction test using the same setup but measuring torque against increasing motor speed. [Overkill] threw in a destructive test, too, with the test specimens grinding against a concrete block at a constant speed to see how long the tire lasted. Finally, there was a road test, with a full set of each tire mounted to an RC car and subjected to timed laps along a course with mixed surfaces.

Results were mixed, and we won’t spoil the surprise, but suffice it to say that molding your own tires might not be worth the effort, and that Flex Seal is as disappointing as any other infomercial product. We’ve seen other printed tires before, but hats off to [Excessive Overkill] for diving into the data.