[asdff]

I assume corrosion is to blame? Crazy how much ocean facing stuff is still done with painted steel. You'd think aluminum and carbon fiber or even plastic would be making strides but it's still the iron age in many ways it seems.

[saturnV]

Carbon fibres themselves may be corrosion resistent, but the fibers by themselves are like a fabric. If you want a solid part instead of cloth, you need to encase the fibers in a resin. Imagine it like a piece of cloth soaked in beeswax or candle wax: it is solid like the resin but if you pull on it, it has the strength of the fibers of the cloth.

The resins used for carbon fibers are usually very bad at contact with water over long periods of time. Even those in aerospace applications require coating/paint if exposed moisture over time. It’s a plastic, even the best ones don’t do so well in water after a few months.

Furthermore, the damage that moisture does to the resin can be difficult to detect and even more difficult if not impossible to fix. It requires clean rooms, skilled labor and machinery that you don’t have in the middle of an ocean.

Then take iron corrosion: it is easy to spot by naked eye, it may not be easy to repair, but it is relatively simple to “halt” further damage by removing the rust and adding new paint.

Don’t get me wrong: carbon fibers are amazing, but sometimes the “boring” solution is best.

PS: steel alloys and coatings can be amazingly high tech too, it’s amazing what can be engineered.

[semi-extrinsic]

Cathodic protection is also a nice option against corrosion on stuff that's connected to the grid anyways.

[xarope]

speaking of carbon fiber and immersion, here's a writeup about Titan's use of carbon fiber:

https://www.popularmechanics.com/science/a60687211/titan-sub...

[zikzak]

All industrial generators undergo regular shutdowns for maintenance and recalibration. This is costly and time consuming when they are on land.

Also, I am thinking about all the ocean factors beyond salt corrosion. There's tons of crap in the water beyond salt and minerals. Like fine grit suspended in it. Plus the tidal forces etc.

[ReaperCub]

Steel has the benefit of fatigue limit. Which means as long as the cyclic stress on steel is under a certain amount it won't fail. Aluminium has a much lower fatigue strength than steel and will always fail given enough cycles.

While rust can be a problem it can be mitigated. Also steel is easier to repair than many other materials (welding).

BTW. Aluminium does suffer from corrosion as well. I used to have racing bike, the wheel nipples (these connect the spokes to the wheel rim) used to corrode to the point where they would fail, which meant I would end up with a buckle. I ended up having both wheel rebuilt with higher quality brass nipples.

Plastics under time also suffers from a different set of issues. Plastics can become brittle. Anyone working on old computers (especially macs) can attest to this.

[Someone]

Corrosion, the force of water (being 800 times as dense as air and effectively incompressible, water forces can be huge), objects in the water (again, water being heavy it can move heavy objects around in its flow), fouling through, for example, algae and mussels (https://en.wikipedia.org/wiki/Fouling)

[dzhiurgis]

AFAIK corrosion is slower underwater. It’s all the shmutz that’s underwater - logs, rocks and boulders that get moved by these huge tidal currents.

[spandrew]

Carbon fibres tend to crack under extreme torque.