Cruisers Forum
 


Join CruisersForum Today

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 03-08-2020, 20:16   #46
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 1,991
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: True Wind without speed transducer

Quote:
Originally Posted by rslifkin View Post
I have always wondered why most sailors focus heavily on speed through water and ignore the GPS speed over ground readout. Coming from a powerboating background, in my mind, what really matters in the end is "how fast am I moving and in what direction?" So SoG and CoG from the GPS tell me that. It doesn't really matter if I'm moving a different direction than I'm pointing, or if I'm moving over ground slower or faster than through the water. That's cool to know occasionally, but is of no use for getting me to my destination.
Answer, Part 1.

Do you wonder why?

Sailboat racers led the way on this, beginning to use True Wind Speed, True Wind Angle, and Speed Through the Water in the 70's to 80's.

The reason is because to get the most out of your boat you need to understand how the sails and hull and keel and rudder are working to maximize your boat speed through the water. If you are fast through the water you will be fast over the ground. We have benchmarks (polar diagrams) and even more important, we are watching our boat speed relative to the true wind, true wind speed and the true wind angle, and the leeway, etc, minute by minute.

We must eliminate as many outside factors as possible, including the effect of current. When you look only at Sog and Cog, you have combined the effects of many things and it is hard to see what each factor is contributing. We need to separate out the components and optimize each one separately.

Current is the responsibility of the tactician and navigator.

Boat speed is the responsibility of the helmsman and trimmers.

So the helm and the trimmers concentrate on boat speed, and for that they need the instrumentation (or a very good seat of the pants feel).

The tactician and navigator watch the competition and where the boat is on the race course and how we are being affected by currents and land masses, etc, and for that they need GPS and current information.

What does any of the mean to a cruising sailor? Well, for most of us, nothing. We motor along merrily drinking a beer with little regard for whether or not we could be doing it faster. Who cares? we're cruising.

But for those who get a thrill out of knowing that they are sailing well, doing the best that they can given the boat and the conditions, we can utilize all of the information available, and strive to do, with just ourselves, what the racer does with a full crew.

Look, sailing is a sport, it is not just a passenger ride.
__________________

__________________
Sailing is a sport, an athletic activity, not a sedentary one.
Fred Roswold-Fred & Judy, SV Wings, Mexico
https://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 03-08-2020, 20:28   #47
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 1,991
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: True Wind without speed transducer

Quote:
Originally Posted by rslifkin View Post
I have always wondered why most sailors focus heavily on speed through water and ignore the GPS speed over ground readout. Coming from a powerboating background, in my mind, what really matters in the end is "how fast am I moving and in what direction?" So SoG and CoG from the GPS tell me that. It doesn't really matter if I'm moving a different direction than I'm pointing, or if I'm moving over ground slower or faster than through the water. That's cool to know occasionally, but is of no use for getting me to my destination.
Answer, Part 2.

You are thinking that you only need to look at SoG and CoG. But if you are interested in a fast transit from one point to the other you can use some more information.

For example, lets say that you know that with a full fuel load, at 7000rpm, you should be able to go 44 mph. You look at your SoG and you see 41 mph.

But is that due to current or lack of boat speed? With good instrumentation you see that your speed through the water is not 44mph but 42mph. You ask why. Looking around you you see that the outdrives are not trimmed where you usually have them. So you make a change. The speed inches up to 43mph, but you are still a bit slow. Finally you decide that the fuel load was not taken on evenly and you trim tab down a little on one side and the boat speed comes up to 44mph

So now you are hitting 44mph and 43 Sog and you know the difference is 1 knot of current against you.

Most of your buddies wouldn't care. By now they are on their third brewski but you know you are doing really well and you are satisfied.

Or not. But if you care, you need those instruments.
__________________

__________________
Sailing is a sport, an athletic activity, not a sedentary one.
Fred Roswold-Fred & Judy, SV Wings, Mexico
https://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 04-08-2020, 05:37   #48
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 923
Re: True Wind without speed transducer

Good point on the current vs speed thing. I tend to note expected wind and current before heading out, so I already have an idea of whether I'm expecting to be a little bit slow or fast.



As far as things like trim (sails or trim tabs on a powerboat), in my mind, it's always a matter of adjust to find maximum speed regardless of which speed you're looking at.
__________________

rslifkin is offline   Reply With Quote
Reply

Tags
transducer, wind

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
True Wind Direction in Magnetic vs True B4A Marine Electronics 0 18-10-2019 07:59
Using Raymarine Wind Transducer Without Calibration or i70s display SpaceRnglr Marine Electronics 5 18-03-2019 10:37
OpenCPN Manual on Ground Wind, True Wind, Apparent Wind Dockhead OpenCPN 11 15-08-2018 20:15
Can I test an autohelm ST50 wind gauge without detaching the transducer from the mast meshugah Marine Electronics 3 02-04-2016 18:33
Wind transducer: True vs. apparent wind? RhythmDoctor OpenCPN 3 04-01-2015 15:28

Advertise Here


All times are GMT -7. The time now is 02:19.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.