Anyone seen underwater turbines on a yacht ? More clutter?
Malizia II has some special features. It uses solar panels and underwater turbines to generate zero-carbon electricity, and carries a laboratory to measure ocean data for climate scientists, including PH, salinity, water temperature and surface CO2.
www.smh.com.au/world/europe/no-air-travel-16-year-old-to-sail-to-new-york-for-climate-summit-20190730-p52c71.html
Up to 0.4kn drag
www.sailmagazine.com/diy/know-how-hydro-generators
I don't have a lot of time at the moment. But "Sailing La Vagabond" has one. Apparently very efficient. I will put a link in when I have more time.
Some of the modern electric sail drives will charge their batteries by letting the propeller run in reverse like a turbin when sailing. Seems like a good concept. And means there's only one prop in the water rather than an extra turbine.
Great on a long passage. Won't do much when anchored. What do cruising yachts spend the VAST majority of their time doing?
Select to expand quoteSailMark said..
Great on a long passage. Won't do much when anchored. What do cruising yachts spend the VAST majority of their time doing?
Neither anchored nor voyaging. Having work done to them.
Select to expand quoteWollemi said..
Anyone seen underwater turbines on a yacht ? More clutter?
Malizia II has some special features. It uses solar panels and underwater turbines to generate zero-carbon electricity, and carries a laboratory to measure ocean data for climate scientists, including PH, salinity, water temperature and surface CO2.
www.smh.com.au/world/europe/no-air-travel-16-year-old-to-sail-to-new-york-for-climate-summit-20190730-p52c71.html
Up to 0.4kn drag
www.sailmagazine.com/diy/know-how-hydro-generators
I'm not convinced! On the average yacht a folding propeller will give about half a knot speed advantage over a free spinning fixed blade propeller. If you applied load to that propeller in the form of a generator or alternator that will take some horsepower and slow the boat further. I think the 0.4kn of drag is BS. Even if the drive is an actual turbine it will take power same as the exhaust in a turbo charged car restricts the exhaust. There is no free lunch!
There were several underwater generators fitted to yachts in the recent GG race. Nearly all the photos showed them in the stowed position. If they had been really successful we would have heard all about it by now.
Select to expand quoteRamona said..
There were several underwater generators fitted to yachts in the recent GG race. Nearly all the photos showed them in the stowed position. If they had been really successful we would have heard all about it by now.
The efficiency comes in when you compare the sponsorship dollar to stowed-weight ratio.
I had one on Kankama about 18 years ago. For boats that want about 5 amps when sailing they are a good idea. The one I had was home built from a permanent magnet DC computer tape drive, a high amp diode and a 3hp outboard prop epoxied onto a stainless shaft. It was good back in the old days before we put 400 watts of solar on the boat. I would chuck the prop off the back, the spinner would spin the rope and the motor and we would get a constant 5 amps all day to cover the autopilot and other stuff. I still have the prop spinner but reckon that with some care I could double amps - nice prop would be better than my old outboard one.
So if you have no space for huge solar, you could make your own for about $100 which is good value.
cheers
Phil
Select to expand quoteKankama said..
I had one on Kankama about 18 years ago.
Phil
Phil, if it's towed via rope, suppose you need to avoid it being thrown against the hull by following waves.
How far from the stern would you tow it, and how thick a rope ?
Never had a problem with it hitting the hull. It was on a 15 metre rope about 10mm thick
Select to expand quoteKankama said..
I had one on Kankama about 18 years ago. For boats that want about 5 amps when sailing they are a good idea. The one I had was home built from a permanent magnet DC computer tape drive, a high amp diode and a 3hp outboard prop epoxied onto a stainless shaft. It was good back in the old days before we put 400 watts of solar on the boat. I would chuck the prop off the back, the spinner would spin the rope and the motor and we would get a constant 5 amps all day to cover the autopilot and other stuff. I still have the prop spinner but reckon that with some care I could double amps - nice prop would be better than my old outboard one.
So if you have no space for huge solar, you could make your own for about $100 which is good value.
cheers
Phil
The problem with towed generators is propellers are extremely inefficient, even when used for drive. Paddle wheels however are much better. Perhaps a paddlewheel arrangement between the two hulls of a catamaran might be worth a try.
I didn't worry about efficiency - I just wanted some amps. It didn't seem to slow us down and catered for all the draw we had from the autopilot. I have a new motor and might make a new spinning version - it is easy to use and deploy so I would not change it much.
The Vendee Globe IMOCA 60s use hydrogenerators. Efficiency can't be to big a problem.
