Comment by ansgri
1 day ago
The importance of repairability is underestimated here. All new infrastructure must be built under assumption that there will be multiple attempts at sabotaging it by actors of various level, and multi-megavolt unrepairable cables that can be fully disabled by one smallish unmanned sub don’t win here at all.
The original version of this post did have a repair plan.
Basically, every few kilometres you turn off the surface hardening of the cable for a yard or two. That spot won't propagate cracks - which means that if someone destroys part of the cable, the rest will be fine.
Those spots of cable have no tensile strength, so you wrap just those spots in a post tensioned steel sheath.
Then, you also make a few spare kilometers of cable that you lay in the ocean floor. When an incident happens, tow a new cable into position and connect it up. Underwater glass forming is a silly idea - but you can simply crack away the glass at the ends, reconnect the aluminium, then encase the whole thing in a couple of yards of epoxy.
The above plan I considered probably was of similar cost to simply laying a new cable across the entire ocean ahead of time in preparation though.
Don't forget ships and their anchors.