Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 11-11-2006, 14:44   #1
Registered User

Join Date: Sep 2006
Location: Victoria, BC Canada
Boat: Spencer 44 ketch - Candine
Posts: 7
Wind Generator Mounting Location

The sticks are down on my Spencer 44 CC ketch with a stoutly rigged mizzen that is about 33 feet off the deck. There is no room astern for a dedicated tower - so aloft it shall go. I purchased a Rutland 913 and now await delivery. I will fabricate the mounting hardware. The options and considerations are 1) below the radar dome - this has the least effect on heeling moment from both windage and weight aloft (about 25 lbs total with mount and hardware), but greatest interference from (and to) sails while underway, and least clean air at anchor. 2) Above the radar dome - which trades off cleaner air (when on the wind) for a higher weight and windage effect, or 3) at the mizzen masthead, which gets the cleanest air of all, for the greatest effect on stability and load on the rig.

The mast head mount on a straignt pole would have less torsional load on the mount - anyone experienced problems with this? The heavier cables for the longer run are not a big concern, and my mizzen stays'l will still see plenty of use with that arrangement. My real question is - just how much of an effect on stability will the unit cause at the various locations, and how much less would it be halfway up? I am not engineer and don't know how to do the math to figure it out, nor interpret the significance of the results. Can anyone help me?

Re the mizzen stays'l - it appears that I'll perhaps still be able to fly it with the generator mounted part way up either above or below the radar, as the sail flys outside the twin mainmast backstays and I just have to be careful when hoisting and dousing. Is this a mistake? Does anyone have experience with this?
candine is offline   Reply With Quote
Old 12-11-2006, 02:53   #2
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,082
Images: 241
Basically, inasmuch as I’m no engineer, either:

The kinetic energy, exerted by the 25 Lb wind turbine will vary as the square of the mounting height.

Hence:
Doubling the mounting height will quadruple the forces exerted on the mast & rig.
Mounting the turbine at 23.3 Ft will result in roughly one-half the loading as mounting at 33 Ft.

Perhaps one of our Engineer, Physicist, or Mathematician members can describe and explain the vectorial kinetic energy calculations.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 16-02-2007, 11:15   #3
Registered User

Join Date: Sep 2006
Location: Victoria, BC Canada
Boat: Spencer 44 ketch - Candine
Posts: 7
Settled on about 40 per cent of the way up, just below the first spreaders. This was based more on the strength of the rig and minimizing loads than anything else.
candine is offline   Reply With Quote
Old 16-02-2007, 11:40   #4
Senior Cruiser

Join Date: Apr 2006
Location: California
Boat: 1980 Endeavour 43 (Ketch)
Posts: 2,457
I too was pondering where I locate a wind gen device. I've seen some CC Ketchs rig using a seperate pole out on the cap rail just forward of the main back stays and almost level with the mizzen. Support, fore and aft, with conventional means, and lateral support to the mizzen with some adjustable supports off the main mizzen support to the shrouds and one of the main backstays.

Dunno ... otherwise, mostly ABOVE the radar dome on the mizzen.
S/V Elusive is offline   Reply With Quote
Old 16-02-2007, 17:54   #5
Registered User
 
Entlie's Avatar

Join Date: Jun 2006
Location: New Bern, NC (Fairfield Harbour)
Boat: 1994 Prout Manta Catamaran
Posts: 248
Just out of reach of your fishing pole, boat hook, or gaff is good.

Entlie
Sailing Catamaran Sunspot Baby
__________________
"Never a ship sails out of a bay
but carries my heart as a stowaway."
-Roselle Mercier Montgomery"
Entlie is offline   Reply With Quote
Old 17-02-2007, 00:12   #6
Registered User
 
Celestialsailor's Avatar

Join Date: Nov 2006
Location: Back in Northern California working on the Ranch
Boat: Pearson 365 Sloop and 9' Fatty Knees.
Posts: 10,466
Images: 5
I also am mounting my 403X. I have a Ketch and to me, the best place is just below the spreaders on my Mizzen for many reasons. 1)If I dismast, it is likely to break just above the spreader. 2)The shorter the run of wire, the less the guage of said wire. 3)With Ratlines, the unit it at least servicable. Good luck.
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"
Celestialsailor is offline   Reply With Quote
Old 15-03-2007, 16:05   #7
Registered User

Join Date: Jun 2006
Posts: 3
There's another factor to consider. Wind velocity seems to increase a whole lot as you get higher off the water. Also, while weight aloft increases heeling moment(bad for racers), it also increases the moment of inertia, contributing to a slower, more comfortable rolling motion(maybe good for cruisers). Early small boat circumnavigator Capt. Voss would sometimes haul an anchor part way up the mast to deal with violent rolling! Some (Including Steve Dashew) even contend that a heavy rig can help prevent capsizing by slowing the boats roll-down from a breaking sea. I think I'm going to put my wind gen atop my mizzen. I've got a heavy boat with a relatively short mizzen. I'll let y'all know how it works out.
captpete is offline   Reply With Quote
Old 02-05-2008, 10:04   #8
Registered User
 
Beausoleil's Avatar

Join Date: Jul 2007
Location: Solomons, MD USA
Boat: Formosa 51 Aft Cockpit Ketch - "Beausoleil"
Posts: 611
Images: 3
Resurrecting an old thread:

I'd preparing to purchase a wind generator (most probably, SWWP's Air Breeze), and want it mounted at the mizzen masthead.

I could probably fabricate a mount, but I've also been searching around to see if I could find something similar to a mount for a vertical base station antenna for hams - a bit beefier version of the mount for my Diamond X50A dual-band vertical antenna (pdf here).

What have our readers done?
Beausoleil is offline   Reply With Quote
Old 05-05-2008, 22:51   #9
Registered User

Join Date: Jan 2008
Location: Hobart Australia
Boat: Hartley RORC 32
Posts: 119
looking at also installing a generator, and trying to figure out if just to put it off the arch over the pushpit or up the mast somewhere
as I was thinking of more wind the higher up also
thoughts will be good for this decision
thanks guys
I will keep watching wait for your mistakes and then make my own
as we all do
well hopefully will learn from you all have achieved to date
thanks again
hooked
hooked on water is offline   Reply With Quote
Old 05-05-2008, 23:35   #10
Registered User
 
Microship's Avatar

Join Date: Dec 2005
Location: living aboard in Friday Harbor, WA
Boat: Vic Franck Delta 50
Posts: 699
Images: 7
Saw one in La Conner today on the MAIN masthead... couldn't quite believe it! Thought it was a giant wind instrument at first (hmmm, actually... wonder if they have a N2K interface for those things?). Anyway, quite a startling sight, but it did find clear air way up there (though at that dock, that's less an issue). Steve
__________________
M/V Datawake
Nomadic Research Labs
Microship is offline   Reply With Quote
Old 06-05-2008, 02:32   #11
Registered User
 
marc2012's Avatar

Join Date: Apr 2008
Location: abbeville la
Boat: seawind II Patience
Posts: 541
wind gen

Kinetic energy = 1/2 mass times velocity squared confused about height issue.Height has more to do with torque?
marc2012 is offline   Reply With Quote
Old 06-05-2008, 08:22   #12
Registered User
 
Beausoleil's Avatar

Join Date: Jul 2007
Location: Solomons, MD USA
Boat: Formosa 51 Aft Cockpit Ketch - "Beausoleil"
Posts: 611
Images: 3
Quote:
Originally Posted by marc2012 View Post
Kinetic energy = 1/2 mass times velocity squared confused about height issue.Height has more to do with torque?
Wind speeds are normally higher aloft than at the surface, due to friction as wind passes over the surface of the water, and any other disturbances it finds in its path.

Of course, adding mass aloft increases the torquing moment (is that the right expression?), and increases loading on the shrouds when the wind pipes up. Granted, the additional forces are slight, but still real.
Beausoleil is offline   Reply With Quote
Old 06-05-2008, 08:53   #13
Registered User
 
Cowboy Sailer's Avatar

Join Date: Aug 2007
Location: on the boat. Gulf Coast
Boat: C&C 38'
Posts: 351
Images: 2
Wind velocity is often assumed to vary as the 1/7 power of height above the surface for planning wind turbine tower sites. The power that can be extracted from the wind varies as the third power of the wind velocity. I generated a little chart that shows the expected wind speed at different heights compared to a height of 30 feet. It revealed that one would expect to lose about 2% of the power available at 30 feet above the surface per foot of decrease below 30 feet. For example at 20 feet above the surface the wind speed would be about 94% and the available power would be 84% of the values at 30 feet. At 10 feet or 20 feet lower the theoretical wind speed would be 85% and the power produced would be 62% of that at a 30 foot height.
__________________
Jerry and Denver
Happy Old cruisers!
Cowboy Sailer is offline   Reply With Quote
Old 06-05-2008, 09:44   #14
Registered User
 
Celestialsailor's Avatar

Join Date: Nov 2006
Location: Back in Northern California working on the Ranch
Boat: Pearson 365 Sloop and 9' Fatty Knees.
Posts: 10,466
Images: 5
Interesting that this thread is up again. As promised I have pictures here for you all. This is a Mizzen mounted bracket I found on e-bay for $150. It was apparently made for a windbugger and had the original store stickers on it for $795!!! The only mod I made was welding a smaller tube inside of the manufacturers socket, to accomodate the 403. I was lucky the width of the bracket was very close to that of my mizzen mast. I mounted it lower than the spreaders and high enough that there hopefully will not be a problem with the mainsail.
Let me know what you think.
Attached Thumbnails
Click image for larger version

Name:	May08 008.jpg
Views:	347
Size:	81.7 KB
ID:	3495   Click image for larger version

Name:	May08 009.jpg
Views:	361
Size:	49.3 KB
ID:	3496  

__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"
Celestialsailor is offline   Reply With Quote
Old 07-05-2008, 19:12   #15
Registered User

Join Date: Jan 2008
Location: Hobart Australia
Boat: Hartley RORC 32
Posts: 119
Thanks cowboy
fantastic calculations for us to work with
now got to look for a clear place in front of the mast that wont fowl the jib
or maybe end up on a post off the arch on the pushpit
see what I can do
near spreaders sounds very good if I can swing it
Thanks hooked
hooked on water is offline   Reply With Quote
Reply

Tags
generator, wind generator

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Weather Basics ~ Reading Weather Charts GordMay General Sailing Forum 6 28-04-2011 15:35
Heavy weather anchoring, Stede General Sailing Forum 105 10-12-2008 10:11
Wind Generator billangiep Electrical: Batteries, Generators & Solar 60 07-06-2008 12:06
Wiring of Wind Generator and Solar Panels Da BigBamboo Electrical: Batteries, Generators & Solar 38 15-10-2007 12:21
Wind Bugger irwinsailor Electrical: Batteries, Generators & Solar 0 27-02-2003 10:36

Advertise Here


All times are GMT -7. The time now is 23:19.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.