Ocean liner in bucket full of water

[DaveC426913]

If you want to everything to stay "rigid", you have two basic choices. Either you do a proper stress analysis, or you just overdesign everything.

Definitely overdesign.

For a small scale experiment, I'm assuming a glass aquarium tank isn't going to deform much under the water pressure, otherwise the glass would crack. You could check that assumption with a measuring rod cut to fit accurately inside the tank when it is empty, and check the amount of clearance when it is full.

I'm pretty sure it would deform by at least a mm or two. It could be mitigated by some internal bracing.

Designing experiments is often a matter of trial and error. Starting with something simple and cheap to find out what is really important in practice is often a good strategy.

I think the danger is that what might work in a scale test will likely not scale up well. We're dealing with masses cubing as we scale. This will be an excellent demonstration of Galileo's square-cube law.

 

[AlephZero]

I'm pretty sure it would deform by at least a mm or two.

Don't speculate. Measure it. That's what experiments are for.

I think the danger is that what might work in a scale test will likely not scale up well. We're dealing with masses cubing as we scale. This will be an excellent demonstration of Galileo's square-cube law.

Of course. But you learn how to run by falling over while trying to walk

 

[cmb]

...you learn how to run by falling over while trying to walk

ermmmm... you can learn that way, but that is not necessarily the way to learn! How did you learn not to walk into the road with oncoming traffic?

 

[AlephZero]

How did you learn not to walk into the road with oncoming traffic?

I probably personally learned that mostly by trial and error, considering I grew up in a place where it was perfectly normal for 6-year-olds to walk a mile and more to school and back every day on their own, with no supervision.

But that's beside the point. Most likely nobody has done this particlear experiment before, you won't figure out how to do it just by asking "experts" for advice.

 

[tony_physic]

If we assume a hemispherical ship 1km diameter the volume is 4/3pi r^3
523598775.6 cubic metres
If the bath is 1cm bigger all round to allow bending etc then volume of bath is
523630182.1
The difference being the water in your bucket 31416.52 cubic metres, a big bucket.
Of course if the gap is smaller less water is required
The easiest way to visulise this working is by filling the bath and then lowering the boat into the water, allowing the bath to overflow until the boat is floating. The remove the boat and fill the bucket with the water that is left.

 

[Per Oni]

Not really. The buoyancy is not involved in the functioning of the hydraulic press (if this is what you have in mind).

No, I was thinking of Dave’s statement of 80 grams supporting the load of 10 kg.

 

[olivermsun]

Most likely nobody has done this particlear experiment before, you won't figure out how to do it just by asking "experts" for advice.

No, but people have floated scale models in buckets, and people have also floated ocean liners in locks (which are just big buckets as far as I can tell).

 

[DaveC426913]

Don't speculate. Measure it. That's what experiments are for.
Of course. But you learn how to run by falling over while trying to walk

Design well before building. We're still in the design phase.

We have to start with the assumption of a certain amount of existing knowledge, or we'd still be testing tree bark as a structural component.

As oliver's mum points out.