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59

The plastic is a bit heavier than water and should sink, however in practice I have experienced that 2x4 bricks (and the like) have a tendency to trap air inside them and actually float rather well. It probably isn't failsafe, however for shorter periods of time (like a half to a full hour) would probably work fine. (I haven't actually tested the time it ...


25

A few years back there was this solid single-piece hulled police boat which would float. There was also a small red boat (pre-2000) that came with part of a pirate set (I believe, anyway) As for building a boat from scratch...no. It tended to capsise then sink (somewhat impressively). Place 2x 4x2 bricks on another and place in water, they only float on ...


22

I had a Police-Boat when I was a child that had a one-piece-body, so it was watertight and able to float: There are some other LEGO-boats with similar bodies (even some bigger ones) that should also be able to float.


18

The main restaurant in the LEGOLAND park in Windsor has quite a lot of LEGO creations in fishtanks. In the same park, the Sealife attraction 'Atlantis Submarine Voyage' has 50 species of sharks, rays and tropical fish that happily coexist with the LEGO models. Keep in mind that LEGO is safe from children saliva, which I'm willing to bet is more aggressive ...


16

There is another not mentioned way to achieve flotation. My kid discovered it today with his "water bat": surface tension. The long flat wings did the trick : ) It is not exactly due to the buoyancy of the bricks themselves as wanted in the question, but might help as a complement. For more on the Physics underlying: Surface tension


15

There are a number of Lego Pneumatic sets with airtight tubes, valves and switches which could be put into use with fluids. One is 9641, Pneumatics Add-On Set. Bear in mind that the pneumatics sets can command a much higer price than those sets with a similar number of parts, and buying individual pieces can also get expensive. Have a look at BrickLink to ...


14

The Atlantis Submarine Voyage ride at LEGOLAND Windsor has almost 100 models (albeit glued together) submerged in a 1,000,000 litre tank with 'upto 50 species of rare sharks, rays and tropical fish'. If LEGO bricks can withstand those conditions, I think you'll be fine. Most of these models are quite large (and heavy), so you may need to weigh down or ...


13

In addition of the various boat hulls, you can use pneumatic tanks for extra buoyancy. If you want to motorize your boat, keep in mind that means extra weight, which has to be countered in some way.


12

I would try liquid latex (liquid frisket) which you can buy in most art supply store. This will not damage the bricks and is easy to peel off. You can apply it using a cheap throwaway brush, either in between the bricks (like a cement wall) or as a thin transparent layer on the whole hull. I recommend the second method because it's fast, straight forward ...


12

My kids had Captain Redbeard's Pirate Ship - it certainly floated in the bathtub! I believe many of the other Lego pirate ships could float, particularly if they had molded single piece hulls - see this list.


11

In my experience, this doesn't work very well. The gaps between LEGO bricks are too wide to hold water. The water will be contained for a short amount of time, but it will eventually leak out through the cracks. Here's an experiment showing how your first example works. Notice the water leaking out the crack in the bottom right: The leak continues to grow: ...


10

My children play with the lego fishing boat (see picture) in our bath tube. This design does have a serious flaw (imo). Even if there are very small water waves in our bath tube, water enters the boat which then becomes to heavy and sinks. So if you are planning to built your own lego boat i would make sure the sides are high enough to prevent water from ...


9

LEGO bricks should be safe for fish. Avoid using small parts that they could mistake for food. You also might be cautious on the paint, but I'm sure it's still safer than the paint used on the cheap stuff you'll find at fish stores.


7

Basic LEGO elements won't get damaged by water, however depending on the condition of your water source, some residue may build up on the elements after prolonged immersion. So if you are thinking about keeping them immersed for a longer time, I would suggest using distilled water.


7

For a very small "boat" - something like a 4x8 plate with 1x8 and 1x2 brick sides it might stay afloat for a short amount of time before the leakage takes it down. For larger stuff, LEGO is just too heavy when you get in to building the necessary structure for a real boat. There were some sealed-hull boat sets I remember from childhood that were designed to ...


7

Yes, if built carefully. When I was a kid I made a number of lego boats to play with in the tub, and later in the pool. The main thing I remember was to make the hull upside down and out of at least two interlocking layers. Lining the inside with plate also helped.


7

Already a correct answer accepted, but... the original question seems to be "do Lego bricks float by themselves?" Most Lego bricks are made of ABS plastic which has a specific gravity greater than 1 (but only slightly). So, they are heavier than water and will not float naturally. You can get small bricks to float initially since small bubbles cling to ...


6

The Lego pneumatic valves are not great for (liquid) fluid experiments as the valves dissipate the return path to atmosphere, so they p*ss water out. And the pneumatic hand pump spring and metal core of the regular pistons rusts in a few days. It's about 15 years since I learn't this :-)


6

Most Lego pieces sink. Some of them will float briefly if they have air trapped inside. Almost any construction of Lego elements will sink as there are gaps between pieces. There are some boat pieces that are designed to float, such as the Police Patrol Boat set from 2016. A Brickset list shows some other boats that float.


6

The method they used to secure the battery/controller was to wrap it in a sealed plastic bag, something similar to this could be done for the motors. It would be more difficult since you would need a water tight bearing for the rotating shaft to exit the sealed bag. These bearings are complicated and will still always allows some small amount of leakage. ...


6

I did something like this once, I cut down a butter tub and built the lego around it, with plates hiding the top edge. It worked very well, but the stale tea that I used for the swamp stained my bricks. I can only think that a brick-built wall with a plastic carrier bag secured by a plate layer at the very top would be your best bet, as none of the bricks ...


5

I would tend to suggest another non-waterproofing solution - build something to hold your ship from underneath, that will safely rest on the bottom of your pool. Of course, if you don't want it to show on the picture, you'll have to be extra careful about how you do it, but I think it's the simpliest solution. What I would do is buy a large plexiglass ...


4

Maybe you don't need to waterproof it. If you are able to fit a block of foam (eg. extruded polystyrene) inside the hull, that will probably be enough to ensure flottability.


4

Since you are willing to use a non-LEGO frame to hold the roof and glue to fix all together, I would recommend buying baseplates in bulk and gluing them onto a wooden frame as if they were shingles. If the gradient and the overlap (vertical between rows and horizontal between individual plates) are correctly matched, the rain won't get inside. For more ...


3

This image of the same model shows that the whole set sits on a frame of bricks. In the inside, you could place bricks underneath wherever necessary to attach the water plates (not only 1x... but maybe 2x10, or several 2x4 in a row). They are invisible, so color and type don't matter. If this row of bricks reaches from one side of the frame to the other, it ...


3

I admittedly don't have the 46x46 = 2116(!) 1x1 clips to properly build this, but I was able to build a small sample to replicate the problem. Because this construction technique eliminates the natural tiny gap between elements, you can't easily reinforce it just by attaching plates and bricks to the underside. This construction is essentially "out of ...


2

No, the LEGO Mindstorms EV3 is NOT waterproof. Any electronic product that is capable of being immersed in water will clearly state in the packaging/manual the level of water protection provided. This may be in the form of an IP Code: Ingress Protection Marking, classifies and rates the degree of protection provided against the intrusion (including body ...


2

Some fairly straightforward physics is your friend here: To determine if something will sink or float in a given medium, you need to know its density. If the density of the object is less than the density of the medium it will float. Standard pool water would have a density around 1g/cm3, salt water is higher (depends on the amount of salt in the water). ...


1

The LEGO bricks themselves will be fine, but if you're adding fish and turning this into an aquarium setting you may need to perform some periodic maintenance on them to keep them looking nice... but lots of people have used LEGOs for aquarium decor with great results.


1

I suspect that water leaking through the hull will not be the real problem you need to solve. Granted, I haven't seen a photo of what you have built, so I might be wrong. I think the real problem you might have is that a Lego boat will be quite a bit less massive than a wooden or steel ship with the same proportions. If you go look up some of the old ...


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