I'm constructing a world where the humanity had to migrate from land to water somewhere in antiquity. In this world, humans are living on seas and rivers. They live both on pier-like and other fixed platforms near the coast as well as on rafts strung together into larger settlements offshore. Fishing and sea-plant farming (algae etc.) are the main sources of food. Ships and boats are pretty much the only means of transportation.

The land still exists (topography is the same as of the real world) - no "Water World" scenario. However, humans only visit it for brief periods (several hours, maybe up to half a day) and only to hunt/gather/acquire wood and other land-only resources. There are no permanent human settlements on land.

If you're curious about the reasons for this (which may or may not be relevant to the answer), check out the sister question.

The merit of this question are the consequences, primarily for technological advancement but also social and economic structure.

• Technology: I'm assuming heavy industry (metalworks, metallurgy) will be severely limited, if not curbed entirely. Both for reasons of practicality (building foundries and smithies on wooden platforms at sea) as well as access to resources (mining out of the question if only brief access to land is possible?) - unless someone can prove me wrong. If so, how will this impact development in general? And in particular, shipbuilding? As ships and boats are a big thing in this setting, I'm interested if it's possible to progress into more advanced ships (carracks, galleons) without the use of metal tools? Also, how will the art of building settlements at sea evolve from piers and rafts?
• Social: Looking for ideas how this way of living will impact beliefs, culture etc.
• Economic: Since such way of living naturally limits the size of settlements, can countries (by our understanding) emerge? Any common currency possible?

I'm constructing a world where the humanity had to migrate from land to water somewhere in antiquity. In this world, humans are living on seas and rivers. They live both on pier-like and other fixed platforms near the coast as well as on rafts strung together into larger settlements offshore. Fishing and sea-plant farming (algae etc.) are the main sources of food. Ships and boats are pretty much the only means of transportation.

The land still exists (topography is the same as of the real world) - no "Water World" scenario. However, humans only visit it for brief periods (several hours, maybe up to half a day) and only to hunt/gather/acquire wood and other land-only resources. There are no permanent human settlements on land.

If you're curious about the reasons for this (which may or may not be relevant to the answer), check out the sister question.

The merit of this question are the consequences, primarily for technological advancement but also social and economic structure.

• Technology: I'm assuming heavy industry (metalworks, metallurgy) will be severely limited, if not curbed entirely. Both for reasons of practicality (building foundries and smithies on wooden platforms at sea) as well as access to resources (mining out of the question if only brief access to land is possible?) - unless someone can prove me wrong. If so, how will this impact development in general? And in particular, shipbuilding? As ships and boats are a big thing in this setting, I'm interested if it's possible to progress into more advanced ships (carracks, galleons) without the use of metal tools? Also, how will the art of building settlements at sea evolve from piers and rafts?
• Social: Looking for ideas how this way of living will impact beliefs, culture etc.
• Economic: Since such way of living naturally limits the size of settlements, can countries (by our understanding) emerge? Any common currency possible?