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Comment by avidiax | Hacker News Reader

To be fair, it does sound like Harris was selling this system. It would explain why he did so much legwork around cataloging ships damaged by lightning and persevered for so long.

It's not clear to me why his system would cost 20x a simple chain or cable.

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Lightning protection systems are very sensitive to resistance in the chain, as any localized bit of it will cause a huge amount of heat there, and non-localized will cause current to branch out to other paths, also causing damage/heat. A typical lightning strike can be from 10,000-30,000 amps at millions of volts.

The damage from lightning doesn’t happen due to the current (as a first approximation), but rather resistance to the current causing heating/damage where the current ends up going - very rapidly, in a way the heat doesn’t have time to dissipate.

Having a working low resistance path to ground means heating (and hence damage!) is reduced or even eliminated.

For an example, see the steam explosion inside the tree here [https://youtu.be/3U8aoiEtVSg], compared to striking a grounded tower 6 times (no damage) [https://youtu.be/ScNzI76ZsiY]

The towers lights didn’t even flicker!

Unless carefully specified and properly maintained, the odds that a random cable or chain (especially when exposed to seawater) will maintain a low impedance path to ground is not good.

I wonder if anyone has tried feeding a skyscraper's lighting rod into a sand battery and let it charge up from lightning alone, so much potential for free energy there.

I am aware of no energy storage system capable of absorbing 250000 Wh in under a second

You just need to use a sufficiently large storage system. One of the proposals of Project Plowshare was to use underground detonation of thermonuclear weapons as a geothermal energy sources.

There is a huge difference between electrical energy trying to find its way to ground the easiest way possible (lightning), and a nuke.

For one, lighting can almost certainly find an easier path than into the battery.

For a nuke, the easiest path (once triggered) is to explode.

It would never strike the lightning rod. The entire reason lightning strikes is due to a circuit between the clouds and ground. If you were to put a "battery" like this somewhere, then the resistance would cause the lightning to go where you don't want it.

The ship is wood and his system required large amounts of copper, including sheeting covering what I understand to be a fairly large part of the hull. I imagine the fitting process was also not inexpensive given that.

> including sheeting covering what I understand to be a fairly large part of the hull

This was done anyway as it was the primary way of getting rid of barnicles, shipworm and other attaching seacreatures. I don't see why this is an additional cost.

Hence the terms copper-bottomed and copper-fastened.

Copper was already on the bottom of the ships by then to stop ship worm (terodo Navalis), it also had the advantage of stopping weed growth.

A quick browse through Wikipedia suggests that entire Royal Navy had copper by the late 1790s.

TIL thanks

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