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 17-03-2017, 06:45   #16
cruiser

Join Date: Jan 2012
Location: Lake Ontario
Boat: Ontario 38 / Douglas 32 Mk II
Posts: 3,250
Re: Replacing Knotmeter impeller while the boat is out.

Quote:
Originally Posted by Suijin View Post
This is the industry standard for calculating apparent wind speed; boat speed readings must be water referenced vs. ground referenced (e.g. if the wind and water are both moving in the same direction at 5 knots, you can't sail...take the analytics from there).

If you don't have a paddlewheel (or sonic reader of STW), you're not going to have wind speed readings.

As far as paddlewheel go, If my boat is going to sit anywhere for more than a few days, I pull the paddlewheel and put in the plug. Takes less time than cleaning the damn thing. And I always put in the plug before hauling the boat, even though if they put the slings where I tell them to it would be clear of them. Peace of mind.
I think you mean true wind speed and angle. Apparent wind speed is what the boat feels, and does not require any vessel speed data; it is solely based on the processed anemometer output.
ramblinrod is offline   Reply With Quote
Old 17-03-2017, 06:49   #17
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: 49,139
Images: 241
Re: Replacing Knotmeter impeller while the boat is out.

Greetings and welcome aboard the CF, Karen.
__________________
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 17-03-2017, 11:27   #18
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Bumping around the Caribbean
Boat: Valiant 40
Posts: 4,625
Re: Replacing Knotmeter impeller while the boat is out.

Quote:
Originally Posted by ramblinrod View Post
I think you mean true wind speed and angle. Apparent wind speed is what the boat feels, and does not require any vessel speed data; it is solely based on the processed anemometer output.


Yes my bad. But if the true wind speed is off then so will be the calculated apparent wind (I'm assuming...interesting question).
__________________
"Having a yacht is reason for being more cheerful than most." -Kurt Vonnegut
Suijin is offline   Reply With Quote
Old 17-03-2017, 16:22   #19
cruiser

Join Date: Jan 2012
Location: Lake Ontario
Boat: Ontario 38 / Douglas 32 Mk II
Posts: 3,250
Re: Replacing Knotmeter impeller while the boat is out.

Quote:
Originally Posted by Suijin View Post
Yes my bad. But if the true wind speed is off then so will be the calculated apparent wind (I'm assuming...interesting question).
Tuther way round.

The apparent wind speed, is based on the anemometer output x a factor to derive the desired speed units.

Whatever that anemometer is turning, is the speed the apparent wind is pushing it.

The true windspeed is derived from the apparent wind speed, apparent wind angle, and vessel speed.
ramblinrod is offline   Reply With Quote
Reply

Tags
boat, knot, knotmeter

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
Replacing impeller with electric pump HKTim Engines and Propulsion Systems 12 16-05-2016 14:40
Standard Horizon Knotmeter Rodz Marine Electronics 6 30-11-2009 19:57
SL50 knotmeter inop reading 0.0 Littlefoot Marine Electronics 2 07-10-2008 03:42
New Knotmeter, wind indicator Starboat Marine Electronics 0 05-09-2007 22:22
How trouble shoot Data MArine knotmeter? zippy Marine Electronics 6 24-07-2006 21:02

Advertise Here


All times are GMT -7. The time now is 14:20.


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.