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How would waves and tides work on a planet that is completely covered by Ocean?

It would have:

  1. Oceans of Similar depth to Earth's
  2. Atmosphere extremely similar to Earth's
  3. Same type of star and distance from star as Earth
  4. Similar Moon to Earth's
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  • $\begingroup$ with a planet fully covered in water point 2 in unachievable: phosphorus would not be made available, plants could not grow and oxygen could not be replenished. $\endgroup$ – L.Dutch Nov 26 '17 at 7:08
  • $\begingroup$ @L.Dutch here is a link to more details on this phosphorous business: link.springer.com/article/10.1023/A:1023499908601 Very concerning... we need a way to get more P into the water! $\endgroup$ – akaioi Nov 26 '17 at 8:27
  • $\begingroup$ If it's a complete water world, would you even notice a tide? Unless you're building structures from the ocean floor to the surface I'd imagine you wouldn't... $\endgroup$ – Xen2050 Nov 26 '17 at 8:34
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Tides would be largely insignificant.

Tides don't have much effect on ships in mid-ocean. The tidal forces of the moon pull the seas up by about 40cm. When this reaches land it causes flows which amplify the effect. If there is no land you just get a gentle 40cm rise and fall in the ocean every 12 hours. I doubt it would even be known by a pre-space age species, as it would need gps-like technology to measure.

Waves would work the same as in our oceans. Without land, dissipation would be slower, but would still occur. So waves wouldn't build up infinitely. If you look at the Southern Ocean, the seas can be "phenomenal" but 100m waves still don't occur. There would be some big waves but nothing that is on a different order of magnitude to the seas on Earth. The Pacific and the Southern Ocean is a pretty good model of what a WaterWorld would look like.

The southern ocean in particular, with its circumpolar currents endlessly circling the globe with no disruption, are the best example. Waterworld would have bands of these currents going in opposite directions based on prevailing winds, which are themselves based on heat convection flows: rotational at the equator, anti-rotational in the tropics, rotational in the 'Roaring 40s' etc. In between would be doldrums with little to no current. — kingledion.

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    $\begingroup$ The southern ocean in particular, with its circumpolar currents endlessly circling the globe with no disruption, are the best example. Waterworld would have bands of these currents going in opposite directions based on prevailing winds, which are themselves based on heat convection flows: rotational at the equator, anti-rotational in the tropics, rotational in the 'Roaring 40s' etc. In between would be doldrums with little to no current. $\endgroup$ – kingledion Nov 26 '17 at 15:47
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Much simpler.

Tides are the result of gravitational attraction between the sun(s) and the moon(s) near to a planet. With one sun and one moon at distances approximately equal to those on Earth, you would have two high tides and two low tides of unequal height each day. This is called a mixed semidiurnal tide and exists in places like the California coast and the North Coast of Australia.

The idea of an all-ocean planet is actually a model used to introduce the idea of tides and is much less complicated than Earth. Here, we have landmasses in the way that interfere with water’s ability to oscillate across the entire globe, creating amphidromic points. On an ocean world, the only “nodes” or places with no tide would be the poles, and there it’d only happen seasonally as the poles wander toward and away from being perpendicular to the ecliptic plane.

Just as on Earth, you’d have the highest tides (aka spring tides) during new and full moons, when the sun and moon are aligned and their gravities work together. The weakest tides (aka neap tides) would happen during the lunar quarters, where the gravity of the sun and the moon are pulling in opposite directions.

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  • $\begingroup$ Nice. How would waves work? $\endgroup$ – Rangoon Nov 26 '17 at 6:45
  • $\begingroup$ Wave mechanics would be essentially the same because your atmosphere is of similar composition. However, they would be much larger because wave size is determined by wind speed and fetch (the distance over which the wind can blow uninterrupted) because your wind speed would be consistently very high without interruptions from continents and your fetch is essentially limitless. Check out the waves in the Southern Ocean, then multiply that by ~10! $\endgroup$ – Dubukay Nov 26 '17 at 16:43

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