Is there a liquid a boat can not float on?

Question

Not including lava, or acid so strong it'll melt the boat. I mean something thats classed as a liquid but not dense enough to float a boat...

OK, Ill rephrase - if you were to take a toy boat that'll happily float in water can you find a liquid that'll not support the weight of the boat? I dont want to fiddle with weight ratio's, or unfloatable (is that a word???!!!) shapes, Im after a liquid that cant support a boat that'll float in common-or-garden everyday water average joe water...

Answer 1

I understand the debate the question has generated. It would make more sense if we said 'if we take a boat that floats in water (normally), is there any other liquid that the same boat would sink into, if placed in it?'

The answer is simply yes, lots. We had a question a while back on yahoo about 'why boats float'. Essentially it's because the density of the boat (the hull and the air it encloses combined, divided by the volume of the boat) is less than the density of the water it is floating in. Water's density is 1000kg per cubic metre. Anything that has a density greater than that will sink, anything less than that will float. The point that was largely missed in that question and answer session was that AIR is not essential in making things things float, it's just that including air in an object is a great way to reduce the density quickly, as it weighs relatively little for the volume it occupies.

Take an oil tanker though, fully laden with refined petrol, no compartments with air in them to speak of (relatively speaking that is). The ship itself weighs say 60,000 tonnes, and the cargo weighs 440,000 tonnes, all up a half a million tonnes (a tonne is a 1000kg). Now if the volume of the ship is 520,000 cubic metres, then it will float, because the density of the ship (hull and cargo) is 961kg per cubic metre, and the density of water is 1000kg per cubic metre.

But if you put that same tanker and carge in a sea of olive oil (density 920kg per cubic metre) the ship would sink like a stone because it (the ship and cargo combined) is more dense than the olive oil that is trying to support it. The link below lists dozens of liquids at 'normal' temperatures that are less dense than water - if you think about them they are the sort of liquids that float in globs on top of water - most of the oils for instance.

The mention of air-entrainment is worthwhile as well, putting bubbles in water makes it 'temporarily' less dense. The 'bubbling up' of methane or carbon dioxide from the sea floor is a plausible explanation for boats that might be sailing along happily one minute, sinking without trace the next when they pass over a column of such 'bubbles'.

You can look at the same question in reverse and consider whether a solid ball of steel will float in anything, and the answer is yes, it will float in mercury because solid steel is less dense than liquid mercury. (And for anyone still 'hung' up' on the 'air' thing, remember that there's no air in a ball of solid steel....).

Good question.

Answer 2

Yes. A boat is a vessel. If a vessel is constructed from a material, and the shape of the vessel does not force the vessel to displace an amount of the liquid equal or greater than the weight of the vessels, then the vessel will sink. You can prove this point by taking a coffee mug and setting it carefully in a tub of water. No matter how careful you are, the mug will settle down in the water to the point that the mug will down flood, and fill with water.

Answer 3

It would depend upon the mass of the boat, and the volume of the liquid. With the right tweaking of that ratio, you could get a boat to sink in any liquid.

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Answer 4

Air is a liquid

Answer 5

no except water with gas purging through it like in the bermuda triangle methane swamps

Answer 6

Maybe something like Paraffin or Ethanol.