Adding wind speed to a small Garmin

kappykaplan · May 10, 2020

The wind instrument doesn't measure true wind speed. Once the wind input gets to the chartplotter or other instrumentation, if speed through the water and course are available, true wind speed and direction are calculated.

dlochner · May 10, 2020

True wind is calculated, basic vectors analysis. To calculate true wind, the instrument needs speed through water (not GPS), apparent wind speed and angle, and boat direction. To get true wind speed and direction the boat must have the wind instruments, a compass or gps to give heading and a knot meter to get boat speed through water.

True Wind vs. Apparent Wind

Learn the basic difference between True Wind and Apparent Wind...

www.nauticed.org

Davidasailor26 · May 10, 2020

The Garmin manual at http://static.garmin.com/pumac/echoMAP_4x-5x-7x-9x_OM_EN.pdf seems to say chartplotters in that series can accept NMEA 0183 sentences for apparent wind speed. So you’d need a masthead NMEA0183 wind transducer. The transducer will read and relay apparent wind, which is just the wind speed and direction relative to the boat. That does not need any input about boat speed. The plotter will then do the vector math to calculate the true wind, by compensating for the boat’s speed and direction.

Many chartplotters can use either GPS or a water speed transducer as the speed source for that calculation. The Garmin manual seems to say it can use either as well (pg. 19). Using speed through the water is the better way to get accurate true wind over water, but if you sail in an area without current GPS will work too. Even in current using the GPS input will give accurate true wind over the land, that just isn’t as valuable if you’re sailing through moving water.

LloydB · May 10, 2020

My understanding of true wind it is the direction the wind is coming from relative to true North.(as if you measured it from a rock in the middle of a fast moving River) My understanding of apparent wind that it's the direction the wind coming from relative to where you're standing and explaining it to somebody. Amplitude of wind will depend upon child you're explaining it to and remembered speed will increase as it falls further below freezing.

Hunter216 · May 10, 2020

RussC said:
I've looked at the Garmin site, but don't see any accessory or referral to anything that I could add to my existing 43dv to give wind speeds. any recommendations? I'm not willing to spend a fortune but just looking at options. I need to get my manual out, but I'm sure even the small Garmin 43 communicates with other devices......... yup NMEA 0183

Before you purchase a wind instrument, cabling etc I thought I should raise a potential issue.

I found this in the spec sheet on the Garmin site

I don’t have any hands on experience with this device but the above implies the input connection would be used for the depth transducer.

I’m not sure you could have a depth transducer AND a wind instrument connected and concurrently transmitting data. Maybe that is accomplished through some switching component?

twalker H260 · May 10, 2020

Just had a quick look at the 43dv install manual. Depth transducer has its own wiring connection, there is a NMEA 0183 cable and you also have a Nmea 2000 Connection. I would likely look for a Nmea 2000 capable wind transducer and get the appropriate cabling at the same time.

install manual here:

http://static.garmin.com/pumac/echoMAP_2016_4_5_Install_EN.pdf

Hunter216 · May 10, 2020

Sorry if I caused any confusion, however @RussC did mention 0183. This is the link to the specs that I was referencing. Looks to be a discontinued product.

echoMAP 43dv | Garmin

echoMAP 43dv chartplotter/sonar combo includes a 4.3-inch high-contrast color display with automatic backlight adjustment.

buy.garmin.com

dlochner · May 10, 2020

LloydB said:
My understanding of true wind it is the direction the wind is coming from relative to true North.(as if you measured it from a rock in the middle of a fast moving River) My understanding of apparent wind that it's the direction the wind coming from relative to where you're standing and explaining it to somebody. Amplitude of wind will depend upon child you're explaining it to and remembered speed will increase as it falls further below freezing.

True wind is the wind you would feel if you were standing still. Apparent wind is the wind you feel as you are moving. True wind is generally reported in relation to north (either M or T, depends on how the MFD is set up). Apparent wind is always reported relative to the boat; an apparent wind of 30° would have the wind coming from 30 degrees off the bow, regardless of the compass heading of the boat. The instruments will often show a green or red indicator to show whether the wind is coming from port or starboard.

shemandr · May 10, 2020

Since the true wind data are derived, if the input for boat speed is inaccurate the TWS is meaningless. Paddlewheel boat speed sensors are notoriously inaccurate. Do you keep it cleaned? Or, Just go in the menus and you can tweak it to what ever you want. We're spending thousands of dollars on instrumentations that are based on a farce. Your money, your boat.

Scott T-Bird · May 10, 2020

I know it's not the preferred input, but I use the GPS for boat speed, not the paddlewheel. At least I know it's more accurate. I don't think our currents are that significant, so I feel more confident with the GPS rather than the paddlewheel, which will clog up almost instantaneously!

Aside from that, I still haven't been able to wrap my head around the concept that speed thru water is the better measure for TWS rather than speed over land. But that's an argument that I'll concede without ever really being able to acknowledge!

twalker H260 · May 10, 2020

After looking at the 2nd posting from hunter216 I did some more poking around on the garmin site. It looks like there may be different versions of the 43dv out there. Some with, some without the nmea2000. Have a look on the back of your unit And see if there are 2 or 3 inputs. If 2 you do not have the Nmea2000.

dlochner · May 11, 2020

shemandr said:
Since the true wind data are derived, if the input for boat speed is inaccurate the TWS is meaningless. Paddlewheel boat speed sensors are notoriously inaccurate. Do you keep it cleaned? Or, Just go in the menus and you can tweak it to what ever you want. We're spending thousands of dollars on instrumentations that are based on a farce. Your money, your boat.

All depends on how obsessed someone is about precision. In most cases it doesn't really matter whether the TWS is 12 knots or 15 knots. Apparent wind is more important for sail selection than TWS. Same with wind direction, Apparent Wind Direction is important for sail trim, TWD is not.

Hunter216 · May 11, 2020

RussC said:
well.... that's disappointing. you are correct, as there are three places for plugs in the back of mine, but only two have connections in them. how many terminals does each protocol require? there are four terminals in each of the two ports.

Maybe a call to Garmin is in order as I don’t want to cause confusion. There should be a model and serial number on your device that will help.

I’m way out of my experience zone and like a broken clock am only right twice a day

but I’m guessing the input port is to connect a depth transducer, the output port is to connect to your VHF radio so the unit can transmit GPS information. Maybe there is a way to connect a wind speed instrument by either disconnecting the depth transducer or use some kind of A/B switch but even then I don’t know if the software on the device would display the data

The unit @twalker H260 referenced has the newer NMEA standard and multiple input capability.

Paul356 · May 11, 2020

Call garmin and talk to tech desk. They are informed.

dave_and_dd · May 11, 2020

Don't mean to keep this slightly off topic, but I'm with Scott T-bird. I can't see how speed through water can be preferable over gps speed to calculate true wind.

Dave

dlochner · May 11, 2020

dave_and_dd said:
Don't mean to keep this slightly off topic, but I'm with Scott T-bird. I can't see how speed through water can be preferable over gps speed to calculate true wind.

Dave

I may have over stated my position. When there is no current, the speed through water should work well. When there is a current SOG is probably better. In the case where the boat is headed directly into a current that is equal to the boat speed, speed through water will match the current speed and the SOG will be 0. In that case both the TWS and AWS will be equal because the boat will be stationary. Given the slow boat speeds involved and that we seldom sail against a current that matches our speed through the water, the difference may be a difference with out a distinction.

AWS and AWD are far more important for sailing than either TWS or TWD.

msmalter · May 11, 2020

I have a Garmin Map 547 GPS. Two years ago I replaced my wind instruments and thru-hulls and went with the Garmin SailPack 52. All the instruments are connected via a NMEA 2000 backbone. It was plug and play and worked as soon as it was powered up. I believe you can change the setup to display different values on your GPS screen, although the small size of the 43DV may not offer this option. I don't know what you consider a fortune. The package I bought was $1499. GNX wind only is $899. The wind transducer is $699, but you need the GND10 box for another $199. No reason to not get the GNX wind with a display. It will cost you another $100 or more in wiring/fittings to install the backbone.

DrJudyB · May 11, 2020

shemandr said:
Paddlewheel boat speed sensors are notoriously inaccurate. Do you keep it cleaned?

We install the transducer almost every time we head out, and remove it when we put the boat away. It stays perfectly clean. And we calibrate it. Easy Peasy.