Would the sub typically have to surface to manually clear the propeller? Or, does it have enough torque to just (noisily) obliterate most entanglements?
They do have divers which can get out without surfacing to deal with some problems, but Nuclear subs can move forward without the propeller.
Water is so dense those stubby wings you see on the side can when angled properly create forward thrust when the sub moves up or down which they can do repeatedly by adding and removing water from a ballast tank. Essentially acting like gliders who can swap gravity to keep going.
So a little less oomph than 2 out of the 5 fuel pumps on a Saturn V, just for an irrelevant comparison ;)
Everything I think about them. As you state, just the fuel pumps (that pump fuel at cryo temperatures) are hundreds if thousands of horsepower and are amazing fears of engineering on their own. Each piece of that engine is like that.
I had the immense privilege of seeing a few F1s in person recently in DC and I was not let down.
Thank you for bringing them up.
Sub propellers have a lot of torque. There's no way that one would really get entangled by seaweed. But thick ropes, cables, and heavy fishing tackle are a risk. Every military sub carries qualified divers who could manually cut it free as a last resort.
The same divers who occasionally "inspect" undersea cables. :)
The sub's standing crew would typically have a few qualified divers trained in just the basics. They would only use open-circuit gear on shallow bounce dives for inspections and light maintenance. Anything more complex would require bringing in a dedicated dive team.
If you’re somewhere you aren’t supposed to be, and you have to dive to fix or inspect something, you don’t want to be sending bubbles up.
You’re on your own in the ocean, whether civilian or military, sub or surface. You have to be able to handle any and all potential issues.
Anyway, he was dive-rated. Closed-circuit breathing is the basis of anesthesia machines and has been for ages (at least 60 years). So for us, a closed-circuit system isn't new - it's something we do every day at work. You just have to account for depth. I'd be shocked if he hadn't done it.
Columbia-class is electric drive, which is absolutely wild to me. Those are monstrous motors.
Source: I ran a reactor on a Virginia-class (not USS Virginia, the subject of the article, but in the same class).
I would guess they test props against real-world commercial fishing nets as part of some qualification process.
I assume enough nets have been run over by various vessels over the centuries that they can simply predict performance by looking at the design and plugging key parameters into a formula or table.
Also, subs now are a lot more capable than they were then.
Second reason why now limited usage, WWII submarines was very limited power, many experts consider them as just high-speed boats with extremely limited underwater capabilities, but modern submarines are really powerful, especially nuclear.
Anti-submarine nets are far, far heavier.[2]
MESH ROPES: - flexible steel galvanized wire rope
This is a single strand, flexible steel galvanized wire rope consisting of 70 wires and 21 hemp yarns. It is one-inch in diameter, has a breaking strength of 98,280 pounds and is internally lubricated and protected against the action of salt water by saturating the fiber cores with a preservative composition. It weighs 1.8 pounds per running foot and is supplied on reels carrying 3,000 feet of wire and weighing 5,000 pounds packed for shipment.
The top support line of a submarine net looks like a bridge cable. The floats are the size of cars or larger.