A riddle

[Nick]

.
You are floating on your boat in a small, landlocked pool tethered by lines ashore (maybe Soay Harbour at low water?)

You drop the anchor.

Does the water level in the pool go up or down.

[Aja]

Can the water be seen to go either up or down?

[marisca]

Where is Archie Meads when you need him? Is anchor on the bottom or dangling? What is the anchor made of? What resolution are you measuring the water level to? Where are the moon and sun during this and is it springs or neaps?

[claymore]

I often find the questions are more important than the answers. Surely there will be a difference depending on the type of anchor you are deploying - The Bruce (Robert on Claymore) will surely displace more water than a rocna or a cqr so which would mean the water level would go up.....

[Nick]

.
FFS . . .

OK, your boat is floating ina landlocked pool. You throw a brick overboard. Does the water level go up or down?

[steveyates]

who would even notice?

[wully]

Neither, the displacement volume is already accounted for aboard the boat.

[claymore]

Cannot Agree Wullyum
The boat wid be lighter sae it wid bounce up and then the watter wid rise wi the brick and feckme - the lockdoon wine has kicked in...

[BlowingOldBoots]

Neither, the displacement volume is already accounted for aboard the boat.

+1

[BlowingOldBoots]

One needs the patience of a saint in this place.

[mm5aho]

Is the volume of the anchor less than that of the equivalent weight of water, which is the displacement?

[solwaycruiser]

The water level will go down?

My theory late on a Friday night is -

On deck the weight of the anchor, say 20kg, will displace 20 litre of water.

When dropped it will displace less than that because it is denser than water so occupies less volume so the water level will go down.

If it was a useless anchor and the top of the anchor was level with the surface the water level would stay the same.

If it was even more useless and it floated with some of it above the water level then the water level would go up.

Of course only in one of the above scenarios would it be an anchor.

[Alan_D]

I agree with solwaycruiser, the water level will go down.

While on board, the anchor will contribute to the overall displacement of the vessel, and will displace its own weight of water. Once it is overboard it will displace its own volume of water, which is obviously less than its own weight of water, otherwise it wouldn't sink. Thus the anchor disiplaces a smaller volume of water when immersed, so the water level will go down (all other things being equal).

[DaveS]

I agree with solwaycruiser, the water level will go down.

While on board, the anchor will contribute to the overall displacement of the vessel, and will displace its own weight of water. Once it is overboard it will displace its own volume of water, which is obviously less than its own weight of water, otherwise it wouldn't sink. Thus the anchor disiplaces a smaller volume of water when immersed, so the water level will go down (all other things being equal).

Agree.

[Nick]

Yep. It will go down.

Well done SC,DaveS and AlanD

Make sure you take this into account in your calculations while anchoring.