4 ms·

It would be interesting how much power you could generate by having a little outboard propeller driving a small generator. It would decrease the speed of your

by jerzyt 6y ago

It would be interesting how much power you could generate by having a little outboard propeller driving a small generator. It would decrease the speed of your yacht, but if you're not on a schedule to get anywhere who cares, right? Another option would be using Peltier effect, although I have no idea how efficient it could be. But sailing in the Polynesia, I'd think that there's a good temp difference between the water below the surface and the top of the boat.

larrysalibra 6y ago
Hydro generators exist! They are relatively expensive for the small amount of power they generate: https://www.sailmagazine.com/diy/know-how-hydro-generators https://www.sailmagazine.com/diy/know-how-hydro-generators
- walrus01 6y ago
  What is a typical price?
  - larrysalibra 6y ago
    According to the article I linked, one that gives max 600 watts costs around US$5000. The market is very small for hydro generators for sailboats. Solar is much cheaper because you can buy products that are targeted at mass market instead of only at sailboats. Source: I was recently purchased by a sailboat.
    - tonyedgecombe 6y ago
      I was recently purchased by a sailboat. And what does your sailboat intend to do with its new purchase?
      - robszumski 6y ago
        Suck his wallet dry is the usual goal I believe.
      - hinkley 6y ago
        Sailboats are very much like a reverse merger. The two happiest days of a boat owner's life: the day they buy the boat, and the day they sell the boat.
      - tertius 6y ago
        Take it for all it's worth!
- rtkwe 6y ago
  They're not fool proof yet and can take a bit of tending unless you really spring for the top of the line. Particularly important is the blade pitch, on the more affordable models that has to be set manually and if you go too fast with an aggressive pitch intended for a lower speed you can break the unit very quickly.
jseutter 6y ago
SV Delos has a great video on power generation methods https://www.youtube.com/watch?v=Osh1ljtgnSU https://www.youtube.com/watch?v=Osh1ljtgnSU . It is a larger boat (58ft?) that is lived on full time and they use a combination of solar, wind and fossil fuel for energy. In another video (can't find it offhand) they talk about propeller driven generation and how it isn't a great solution for them. Propeller driven generation is expensive, it requires another hole in the bottom of the boat, requires maintenance (marine growth), it only works when the boat is moving, and its power ultimately comes from the wind or fossil fuels. Why not get the energy from the wind directly using a wind generator? It's cheap, effectively maintenance free, runs whenever the wind blows even at anchor, and if you're running the engines, more efficient to generate electricity using the generator. They have the wind generators mounted above and slightly off the back of the boat, where they are out of the way and remain permanently. They mention their energy generation mix is about 10% wind, 25% fossil, and the rest solar, using 3 panels. Their numbers were generated in low latitudes where solar insolation is quite high, so kind of the sweet spot for solar. I imagine further north wind generation is comparatively more useful. I know more recently they have added some flexible panels on the canopy which added a bit more capacity. I'm guessing that Peltier generation is not going to be effective for anything more than fractions of a watt. The studies I see online all work with larger temperature differentials, like > 50 deg C, which you aren't going to find anything close to in a thermocline layer. To work with a smaller temperature differential you would need to increase surface area immensely, and water is a high-drag environment. I found it interesting that one of the more power-hungry things on a sailboat is fresh water. Watermakers consume 15-30 Wh of energy per gallon, and a boat will need about 20 gallons per day per person. For a 4 person boat, that 80 gallons requires 80*15=1200Wh each day. Most sailboats will use the generator to fill up the freshwater tank because they don't have enough solar capacity.

by jerzyt 6y ago

larrysalibra 6y ago

Hydro generators exist! They are relatively expensive for the small amount of power they generate: https://www.sailmagazine.com/diy/know-how-hydro-generators https://www.sailmagazine.com/diy/know-how-hydro-generators

walrus01 6y ago
What is a typical price?
- larrysalibra 6y ago
  According to the article I linked, one that gives max 600 watts costs around US$5000. The market is very small for hydro generators for sailboats. Solar is much cheaper because you can buy products that are targeted at mass market instead of only at sailboats. Source: I was recently purchased by a sailboat.
  - tonyedgecombe 6y ago
    I was recently purchased by a sailboat. And what does your sailboat intend to do with its new purchase?
    - robszumski 6y ago
      Suck his wallet dry is the usual goal I believe.
    - hinkley 6y ago
      Sailboats are very much like a reverse merger. The two happiest days of a boat owner's life: the day they buy the boat, and the day they sell the boat.
    - tertius 6y ago
      Take it for all it's worth!
rtkwe 6y ago
They're not fool proof yet and can take a bit of tending unless you really spring for the top of the line. Particularly important is the blade pitch, on the more affordable models that has to be set manually and if you go too fast with an aggressive pitch intended for a lower speed you can break the unit very quickly.

jseutter 6y ago

SV Delos has a great video on power generation methods https://www.youtube.com/watch?v=Osh1ljtgnSU https://www.youtube.com/watch?v=Osh1ljtgnSU . It is a larger boat (58ft?) that is lived on full time and they use a combination of solar, wind and fossil fuel for energy. In another video (can't find it offhand) they talk about propeller driven generation and how it isn't a great solution for them. Propeller driven generation is expensive, it requires another hole in the bottom of the boat, requires maintenance (marine growth), it only works when the boat is moving, and its power ultimately comes from the wind or fossil fuels. Why not get the energy from the wind directly using a wind generator? It's cheap, effectively maintenance free, runs whenever the wind blows even at anchor, and if you're running the engines, more efficient to generate electricity using the generator. They have the wind generators mounted above and slightly off the back of the boat, where they are out of the way and remain permanently. They mention their energy generation mix is about 10% wind, 25% fossil, and the rest solar, using 3 panels. Their numbers were generated in low latitudes where solar insolation is quite high, so kind of the sweet spot for solar. I imagine further north wind generation is comparatively more useful. I know more recently they have added some flexible panels on the canopy which added a bit more capacity. I'm guessing that Peltier generation is not going to be effective for anything more than fractions of a watt. The studies I see online all work with larger temperature differentials, like > 50 deg C, which you aren't going to find anything close to in a thermocline layer. To work with a smaller temperature differential you would need to increase surface area immensely, and water is a high-drag environment. I found it interesting that one of the more power-hungry things on a sailboat is fresh water. Watermakers consume 15-30 Wh of energy per gallon, and a boat will need about 20 gallons per day per person. For a 4 person boat, that 80 gallons requires 80*15=1200Wh each day. Most sailboats will use the generator to fill up the freshwater tank because they don't have enough solar capacity.