6 ms·

Assuming you're not just following the water flow, you should also be able to have an under-water turbine to generate even more water than you could with a wind

by phh 3y ago

Assuming you're not just following the water flow, you should also be able to have an under-water turbine to generate even more water than you could with a wind turbine. (technically that power would still come from the wind, but from the sail you already have)

wffurr 3y ago
Said underwater turbine is already present: the prop. As a bonus, it can reduce rigging loads at hull speed by dissipating some energy.
- thinkingkong 3y ago
  Drag via the prop is nowhere going to reduce load at all. The resistence is the same and the force is square of the speed and surface area. So some drag ain’t doing anything. Even in a dangerous sea a drogue and lines would help, but way more than the surface area of a slowly or free spinning prop would offer.
- deleted 3y ago
  [deleted]
JshWright 3y ago
Hybrid sailboats are already a thing. An electric motor/generator sits in line with the traditional diesel engine and can a) drive the prop shaft, b) harvest power when the engine is turning the prop shaft, c) generate power by running the engine with the prop shaft clutch disengaged, or d) (the one you’re getting at) passively generate power when under sail by disengaging the clutch from the engine side and letting the prop spin the generator. Sailboat props are often variable pitch to allow for better efficiency (i.e. they can be turned completely parallel with the flow of water when not in use), which also allows them to be set at an optimal angle for power generation (with minor speed losses, obviously).
- briffle 3y ago
  H&H catamarans has some nice diagrams on how theirs work: https://www.hhcatamarans.com/ecodrive https://www.hhcatamarans.com/ecodrive
  - JshWright 3y ago
    Ah, cool, those are great diagrams! I first heard about this system design from the Tally Ho rebuild: https://youtu.be/xohxmwPfctg?si=RoJV2za9ZgPldrJJ&t=1497 https://youtu.be/xohxmwPfctg?si=RoJV2za9ZgPldrJJ&t=1497

by phh 3y ago

wffurr 3y ago

Said underwater turbine is already present: the prop. As a bonus, it can reduce rigging loads at hull speed by dissipating some energy.

thinkingkong 3y ago
Drag via the prop is nowhere going to reduce load at all. The resistence is the same and the force is square of the speed and surface area. So some drag ain’t doing anything. Even in a dangerous sea a drogue and lines would help, but way more than the surface area of a slowly or free spinning prop would offer.
deleted 3y ago
[deleted]

JshWright 3y ago

Hybrid sailboats are already a thing. An electric motor/generator sits in line with the traditional diesel engine and can a) drive the prop shaft, b) harvest power when the engine is turning the prop shaft, c) generate power by running the engine with the prop shaft clutch disengaged, or d) (the one you’re getting at) passively generate power when under sail by disengaging the clutch from the engine side and letting the prop spin the generator. Sailboat props are often variable pitch to allow for better efficiency (i.e. they can be turned completely parallel with the flow of water when not in use), which also allows them to be set at an optimal angle for power generation (with minor speed losses, obviously).

briffle 3y ago
H&H catamarans has some nice diagrams on how theirs work: https://www.hhcatamarans.com/ecodrive https://www.hhcatamarans.com/ecodrive
- JshWright 3y ago
  Ah, cool, those are great diagrams! I first heard about this system design from the Tally Ho rebuild: https://youtu.be/xohxmwPfctg?si=RoJV2za9ZgPldrJJ&t=1497 https://youtu.be/xohxmwPfctg?si=RoJV2za9ZgPldrJJ&t=1497