3 ms·

Thanks! My acceptance of the idea that drag might be manageable has to do with volume displacement and not surface area. A long shallow "tail" could exert ord

Thanks! My acceptance of the idea that drag might be manageable has to do with volume displacement and not surface area. A long shallow "tail" could exert orders of magnitude less drag (vis a vis surface area) than a deep heavy hull pushing up a big wake. (Related to why boats are long and narrow...) https://en.wikipedia.org/wiki/Wave-making_resistance https://en.wikipedia.org/wiki/Wave-making_resistance Edit: The fact that you see that as a clear non-starter has me wading into Google results for hydrodynamics. It is definitely over my head, but I am curious. Is there a rule of thumb for drag in water that I'm not finding? https://www.boatdesign.net/threads/wetted-surface-area-approximate-formulas.930/ https://www.boatdesign.net/threads/wetted-surface-area-appro... http://www.engr.mun.ca/~bveitch/courses/r-p/Assignments/ITTC-calculation-procedures-Lab1.pdf http://www.engr.mun.ca/~bveitch/courses/r-p/Assignments/ITTC... http://www.fade.up.pt/cifi2d/files/effect-of-wetted-surface-area-on-friction-pressure-wave-and-total-drag-of-a-kayak.pdf http://www.fade.up.pt/cifi2d/files/effect-of-wetted-surface-...

LeifCarrotson 8y ago
My assertion that it's a non-starter is based on the area of an 80 MW solar farm, not hydrodynamics. 80,000 kW x 24 hours / 1 kWh/m^2 = 2,000,000 square meters of solar cell area. That's a lot. In contrast, the ship has an area of 24,000 m^2. A light-weight solar system might weigh 10 kg/m^2, so the whole thing weighs 20,000 tons. The ship has a staggering capacity of 200,000 tons. So yes, it can carry it, but the 'long shallow tail' is really long - literally 20 miles, if it's the same 60m width as the ship - and really shallow. Maybe that's low drag, but if so, why wouldn't they build ships like that?
- cwmoore 8y ago
  That is an interesting result. A 20 mi long piece of electronics floating in the open ocean would have [:deadpan:] more prohibitory issues than drag. Even if it were more optimistically estimated, this has obvious maneuverability (not to mention production) problems. They build ships the way they do for smart reasons, but I do like to explore the possibility space. The application that no one will ever pay for might be a permanent, autonomous, very large, plastic garbage consuming vessel in the Pacific Gyre. The form factor is less a limitation (in theory) than the will to allocate resources in such a way.
  - cwmoore 8y ago
    Somebody made a way to start cleaning this up, and a proposal to pay to do it (front page 3 days later): https://news.ycombinator.com/item?id=17899395 https://news.ycombinator.com/item?id=17899395

LeifCarrotson 8y ago

My assertion that it's a non-starter is based on the area of an 80 MW solar farm, not hydrodynamics. 80,000 kW x 24 hours / 1 kWh/m^2 = 2,000,000 square meters of solar cell area. That's a lot. In contrast, the ship has an area of 24,000 m^2. A light-weight solar system might weigh 10 kg/m^2, so the whole thing weighs 20,000 tons. The ship has a staggering capacity of 200,000 tons. So yes, it can carry it, but the 'long shallow tail' is really long - literally 20 miles, if it's the same 60m width as the ship - and really shallow. Maybe that's low drag, but if so, why wouldn't they build ships like that?

cwmoore 8y ago
That is an interesting result. A 20 mi long piece of electronics floating in the open ocean would have [:deadpan:] more prohibitory issues than drag. Even if it were more optimistically estimated, this has obvious maneuverability (not to mention production) problems. They build ships the way they do for smart reasons, but I do like to explore the possibility space. The application that no one will ever pay for might be a permanent, autonomous, very large, plastic garbage consuming vessel in the Pacific Gyre. The form factor is less a limitation (in theory) than the will to allocate resources in such a way.
- cwmoore 8y ago
  Somebody made a way to start cleaning this up, and a proposal to pay to do it (front page 3 days later): https://news.ycombinator.com/item?id=17899395 https://news.ycombinator.com/item?id=17899395