Towed Generator that We Really Need - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Like Tree2Likes
Reply
 
LinkBack Thread Tools
  #11  
Old 01-27-2013
chucklesR's Avatar
Senior Member
 
Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Posts: 5,978
Thanks: 10
Thanked 30 Times in 30 Posts
Rep Power: 10
chucklesR is a jewel in the rough chucklesR is a jewel in the rough chucklesR is a jewel in the rough
Re: Towed Generator that We Really Need

I keep coming back to the "no such thing as a free lunch" thought pattern.

That Honda 2000 generator putting out 1600 watts is needing a 3.5 hp engine to do so.

Dropping a towed generator over the side, or attached to the transom - if it generates 1600 watts of power, guess what? It's the same as hooking a 3.5hp engine running in reverse.

That's not drag, that's propulsion the wrong way.

If the marine industry really wanted to do something smart they would put a take off on the propeller shaft in front of the stuffing box running a belt drive to a low rpm alternator.
Of course then the whole folding prop market would go out of business.
__________________
Lessons learned are opportunities earned.
Reply With Quote Share with Facebook
  #12  
Old 01-27-2013
guitarguy56's Avatar
Senior Member
 
Join Date: Oct 2012
Posts: 522
Thanks: 6
Thanked 18 Times in 17 Posts
Rep Power: 3
guitarguy56 is on a distinguished road
Re: Towed Generator that We Really Need

Why re-invent the wheel? These products are here already to buy and install and from the video and the website of the product... it seems a viable product?

DouGen and the video of the product in full use in the water and
to wind...

Nick
Reply With Quote Share with Facebook
  #13  
Old 01-27-2013
Senior Member
 
Join Date: Feb 2012
Location: New Orleans Louisiana
Posts: 2,007
Thanks: 6
Thanked 48 Times in 45 Posts
Rep Power: 3
Stumble is on a distinguished road
Re: Towed Generator that We Really Need

Chuckles,

It's been done. An there are numerous threads here and on other forums detailing it. The issue is they don't really work very well. They do produce power, and lots of it, but lets just look at some issues with doing this.

1) prop size was optimized for pushing the boat, not turning a shaft. Pitch, shape, are backwards from what you really need for a water turbine

2) prop size and pitch are really wrong. First every boat has a different size/pitch prop that was selected to push the boat thru the water at a given speed and absorb a given amount of power based upon the engine of that boat. But most boats are likely to need roughly the same size generating prop, because speeds will be close to the same, and the size of the alternator will be roughly the same.
__________________
Greg Rubin
Attorney
Reply With Quote Share with Facebook
  #14  
Old 01-27-2013
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,710
Thanks: 2
Thanked 93 Times in 91 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Towed Generator that We Really Need

"If the marine industry really wanted to do something smart they would put a take off on the propeller shaft in front of the stuffing box running a belt drive to a low rpm alternator. "
People have done that. The "marine industry" is concerned with making profits, not crafting boats, which is why it is an industry. And there's just no profit to be made in niche markets for tiny numbers, compared to industrial ones.

Before there was an internet people read books. Composed by authors, not sniping at tiny slices of subjects. I'm sure I've read about water generators, towed and shaft alike, in cruising books written in the 70's.

Putting an extra pulley and belt on the propshaft is easy. IF there's room in the engine space. IF there's room on the shaft. And IF you add a bearing to take the extra side loading off your stuffing box and cutless bearing.

Towing a genset is easy. If nothing eats it or fouls it and the seals hold. The latest iteration seems to be transom-mounted to avoid that. If they're also using new motor technology, rare earth magnets and the like, and getting enough efficiency...they're still expensive. And still need seals on a rotary shaft operating in salt water.

I suspect there's a reason why 30, 40 , 50 years down the line, this "solution" still hasn't become mainstream.
Reply With Quote Share with Facebook
  #15  
Old 01-27-2013
bobmcgov's Avatar
baDumbumbum
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,056
Thanks: 0
Thanked 25 Times in 24 Posts
Rep Power: 8
bobmcgov will become famous soon enough
Re: Towed Generator that We Really Need

Quote:
Originally Posted by guitarguy56 View Post
Why re-invent the wheel? These products are here already to buy and install and from the video and the website of the product... it seems a viable product?

DouGen and the video of the product in full use in the water and conversion to wind...

Nick
Nick: Because the DuoGen is a miserable piece of equipment with corrosion problems and weak output. Because the same piece of equipment cannot work effectively in air at 15kts and water (100 times denser) at 6kts. It's not a good solution; if it were, you would see them on boats rather than on YouTube.

Chuckles: All the above issues were covered in the "Hacking a trolling motor" thread. As Greg says, a propeller is not an effective generating rotor. You cannot belt the shaft because you will lose 2/3rd of your power to pulley or gearbox friction. The very best water generators (Watt&Sea) produce ~500W max, more like 250W at cruising speeds. That isn't 3.5 hp -- that's 1/3 to 2/3 hp. And that's a purpose-designed device, without the inherent compromises and losses of an engine shaft, hacked trolling motor, or air/water combination machine. Supposedly the Ferris units are better than the DuoGen, but they require a substantial rotor conversion.

Water generation is a good solution for frequent passagemakers. That's a fairly small market for a device that is not easy to engineer properly. The OP's idea of a purpose-built, dual-function troller/hydro-gen is perfectly feasible -- but creating one that worked adequately in both modes would take more R&D than the likely sales volume would justify. Pity, cuz I would lust after such a thing.
__________________
Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
Reply With Quote Share with Facebook
  #16  
Old 01-27-2013
THEFRENCHA's Avatar
Senior Member
 
Join Date: Jan 2003
Posts: 118
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 12
THEFRENCHA is on a distinguished road
Re: Towed Generator that We Really Need

What about these ?
Hydrogénérateurs Watt&Sea : votre voilier autonome en énergie |
They are on most racing sailboat such as IMoca During the Vendee Globe and have proven to be effective and reliable with minimum drag
Reply With Quote Share with Facebook
  #17  
Old 01-27-2013
THEFRENCHA's Avatar
Senior Member
 
Join Date: Jan 2003
Posts: 118
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 12
THEFRENCHA is on a distinguished road
Re: Towed Generator that We Really Need

Type Hydrogénérateurs Watt&Sea : votre voilier autonome en énergie | for the English version
Sorry !
Reply With Quote Share with Facebook
  #18  
Old 01-27-2013
Senior Member
 
Join Date: Dec 2010
Posts: 3,720
Thanks: 0
Thanked 130 Times in 116 Posts
Rep Power: 4
JonEisberg will become famous soon enough
Re: Towed Generator that We Really Need

Quote:
Originally Posted by THEFRENCHA View Post
What about these ?
Hydrogénérateurs Watt&Sea : votre voilier autonome en énergie |
They are on most racing sailboat such as IMoca During the Vendee Globe and have proven to be effective and reliable with minimum drag
They've already been noted in another recent thread on this subject...

Unfortunately, their current price of over $5K US is probably a bit more than most cruisers are gonna be willing to spend on a hydrogenerator...
Reply With Quote Share with Facebook
  #19  
Old 01-27-2013
guitarguy56's Avatar
Senior Member
 
Join Date: Oct 2012
Posts: 522
Thanks: 6
Thanked 18 Times in 17 Posts
Rep Power: 3
guitarguy56 is on a distinguished road
Re: Towed Generator that We Really Need

Quote:
Originally Posted by JonEisberg View Post
They've already been noted in another recent thread on this subject...

Unfortunately, their current price of over $5K US is probably a bit more than most cruisers are gonna be willing to spend on a hydrogenerator...
These look nothing more than glorified trolling motors with the proper pitch props...
Reply With Quote Share with Facebook
  #20  
Old 01-27-2013
guitarguy56's Avatar
Senior Member
 
Join Date: Oct 2012
Posts: 522
Thanks: 6
Thanked 18 Times in 17 Posts
Rep Power: 3
guitarguy56 is on a distinguished road
Re: Towed Generator that We Really Need

Quote:
Originally Posted by bobmcgov View Post
Nick: Because the DuoGen is a miserable piece of equipment with corrosion problems and weak output. Because the same piece of equipment cannot work effectively in air at 15kts and water (100 times denser) at 6kts. It's not a good solution; if it were, you would see them on boats rather than on YouTube.

(
I don't know... do you own one or did at one time? That wasn't the only post on YouTube for the DuoGen... but it seems they might be popular in European sailboats... also in the marina I'm in I looked to see who has a wind generator and surprisingly I did not see one single wind generator in operation! We get a lot of high winds coming in from Puget Sound and it would be of benefit to get some of these wind generators at least to get off shore power...

Nick
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hacking a trolling motor into a towed type generator peterchech General Discussion (sailing related) 43 01-19-2013 01:22 PM
Sailboat Towed off Alki tager General Discussion (sailing related) 35 03-19-2010 08:45 PM
Help costing a generator and lots of generator questions... labatt Gear & Maintenance 10 10-16-2008 01:01 AM
Towed Alternator? jjablonowski Gear & Maintenance 7 06-20-2008 10:34 AM
Portable towed watermakers Mumec Gear & Maintenance 26 10-08-2007 10:51 PM


All times are GMT -4. The time now is 10:42 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.