# Garmin GPSMAP 640



## Yamsailor (Jun 7, 2006)

Anyone have any experience with this new unit? I looking for reviews.


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## Yamsailor (Jun 7, 2006)

More specifically, 

1) Can one use international charts on the Garmin GPSMAP 640 or can you use only US coastal charts?

2) Are all the preloaded charts unlocked?


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## sailingdog (Mar 19, 2006)

YamSailor—

You can use any of the BlueChart or BlueChart G2 charts on the unit. The preloaded charts aren't locked per se, but they're built into the ROM on the unit, so not transferable either. The 640 is basically a brand new unit, and I doubt anyone has gotten their hands on it for a review yet. 

One thing I'm not crazy about with the 640 is that it relies on a touch screen. If you're sailing in colder weather and wearing gloves, I doubt it will respond to you properly. I generally don't recommend getting equipment that relies on a touch screeen for a boat.


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## bubb2 (Nov 9, 2002)

Dog, garmin says the blue charts are pre-loaded in the 640! Screen size would be a issue with me. Basically 4.5"W x 2.7"H , note card size. For $1200 these old eyes want a bigger screen. I would think you could buy a 545 Garmin (3 x 5 screen) and have plenty left over to get a nice street pilot.

https://buy.garmin.com/shop/shop.do?pID=14898


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## sailingdog (Mar 19, 2006)

Yes, but if you want to use charts for any areas that aren't PRE-LOADED, like say, Europe or the South Pacific, it will allow you to use them. It is only pre-loaded with certain charts, usually either the Inland US or Coastal US waters. He, the OP, was asking about international charts.



bubb2 said:


> Dog, garmin says the blue charts are pre-loaded in the 640! Screen size would be a issue with me. Basically 4.5"W x 2.7"H , note card size. For $1200 these old eyes want a bigger screen. I would think you could buy a 545 Garmin (3 x 5 screen) and have plenty left over to get a nice street pilot.
> 
> https://buy.garmin.com/shop/shop.do?pID=14898


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## bubb2 (Nov 9, 2002)

They have card slots. You buy the chip you want.

Garmin: Cartography - BlueChart g2 Vision - Atlantic


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## Yamsailor (Jun 7, 2006)

OK--based on what you have all said I believe you are more informed than I about the technology so I am going to explain to you what I need and maybe you can suggest appropriate unit:

I need a portable chart plotter for three reasons:

1) I do not own a cruising sailboat;
2) I charter sailboats both in the US, Caribbean, Mediterranean and soon-to-be other places so I would like to bring this unit with me (in addition to my paper charts);
3) I am a sailing instructor and sometime use the device to teach the basic pros and cons for GPS Chart Plotters versus traditional piloting.

Which unit do you guys recommend?


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## sailingdog (Mar 19, 2006)

I'd recommend something more like the Garmin 478 unit. The problem with the 640 is that it is really designed to be permanently mounted. The Garmin 478, which looks like this:









is designed to be portable, and can actually operate without being plugged in for about 12 hours due to having an integrated rechargable battery. You can buy a bean bag mount for it as well. I have the older 276 Plus unit. The 478 comes with the US Coastal charts preloaded and can use the Bluechart charts for areas outside of the US coastal waters.

The screen is a bit smaller, but for what you're doing, this is the only unit that really makes sense. It also can be used in a car for automotive navigation as well...so it really is a decent dual purpose unit.


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## Yamsailor (Jun 7, 2006)

Cool--I'll check it out.

One question: What type of charts is this unit capable of handling? Bluecharts? G2?

Thanks SailingDog!


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## sailingdog (Mar 19, 2006)

Bluechart, don't believe it can handle the G2 variants...but check the manual... downloadable at Garmin's website to be sure.


Yamsailor said:


> Cool--I'll check it out.
> 
> One question: What type of charts is this unit capable of handling? Bluecharts? G2?
> 
> Thanks SailingDog!


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## floatsome (Jul 5, 2008)

I don't get this spec: "Supports DSC (displays position data from DSC capable VHF radio)" -- shouldn't that be "to" not "from"? It is NMEA 0183-capable, and I would have thought the 620 could be connected to a DSC radio to supply the radio with position data.


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## floatsome (Jul 5, 2008)

The manual is online: http://www8.garmin.com/manuals/GPSMAP640_GPSMAP640OwnersManual.pdf.

The 640 looks interesting, based on my quick read of that manual. Some comments/uncertainties:

1. Close to my personal sweet spot -- Can be used on our small sailboat for local summer coastal cruising augmented by laptop down below, and in the car or on vacations (portable). See also point 11.
2. Price point is up there - phew. Can get much larger screens from other manufacturers for less, but Garmin does make nice stuff. The price makes me think twice, though.
3. Can integrate XM satellite weather data.
4. Nice integration of AIS and other position data from a DSC radio, at least on paper, and presuming other people use their DSC radios.
5. Not clear to me how to network this device with a DSC radio and a wind meter, at a minimum. The 640 is NMEA 0183-capable, so is the idea to bus the 640 with other devices, presuming the 640 can supply the GPS sentences required by the other devices? Is NMEA 0183 enough these days, now that NMEA 2000 is out?
6. Screen is small, but I've been living with GPSMap 76C for years now, the 640 screen is twice the size, and that size of screen has found a big consumer automotive market, so it works for many.
7. Nice options for connecting to a computer for planning: SD card (though it is buried under the battery) and USB mini-port.
8. Short battery life compared to the 76C, so will need to ensure DC power is available.
9. I am not clear on whether the 640 can send position data to the DSC radio.
10. Garmin insists on calling intended tracks "course", and using "track" for "breadcrumb trail of past GPS fixes representing tracks made good", and using "heading" instead of "course being steered", but that's just my own pet peeve, shared by the tiny minority of consumer navigators, and I can work around it.
11. Speaking of consumers, this thing is a cool toy for the average recreational boater: decent marine navigation aid, but capable of good automotive navigation, displaying photo slide shows, and listening to XM audio by patching to exertnal speakers. They know their market.

On a serious long range cruise and bigger boat, I'd want a bigger screen and more chartplotting/networking capability, but I've got this product on my think-about list for our purposes.


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## sailingdog (Mar 19, 2006)

*A good full-feature DSC Class D VHF radio will have both NMEA 0183 in and out. * *

NMEA IN*-so that it can broadcast your position if you call for help. *

NMEA OUT*-so that if someone else calls for help, it can plot them on your chart plotter... so you know where they are according to their DSC-broadcasted position.

Many of the low-end VHF units do not support this feature, but it is a good feature to have on your radio. For instance, if you call up a friend via their MMSI, you can see where they are in relation to where you are if they respond with a position update. If you're out fishing and want them to know where you're catching all the fish, but not have to announce it via voice....DSC is a good way to do it.



floatsome said:


> I don't get this spec: "Supports DSC (displays position data from DSC capable VHF radio)" -- shouldn't that be "to" not "from"? It is NMEA 0183-capable, and I would have thought the 620 could be connected to a DSC radio to supply the radio with position data.


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## floatsome (Jul 5, 2008)

sailingdog said:


> *A good full-feature DSC Class D VHF radio will have both NMEA 0183 in and out. *


I know that (taught the course for several years), but I did not see in the literature that the 640 is able to supply the radio with the host boat's position data in order to transmit the boat's position digitally, unless I missed something. It only talked about the 640 receiving position data from other boats via the radio receiver. Maybe that single NMEA link is two-way, and the literature simply did not specify it, or I missed it.


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## sailingdog (Mar 19, 2006)

Floatsome-

If the VHF is DSC capable, it has to accept NMEA information in at a minimum, so that the DSC broadcast can send GPS based LAT/LON information during a distress call. The better DSC-capable radios, like the Icom M504 I use and unlike the Raymarine Ray54 VHF I used to use, can send GPS LAT/LON information to the chartplotter, so that an icon/waypoint for the sender's location appears when you receive it. *Any GPS that is NMEA 0183 capable will provide the LAT/LON information to a DSC-capable VHF that is properly connected to it. *

NMEA, being a serial protocol is a unidirectional protocol for each set of wires... there is always an *NMEA data out* and a separate *NMEA data in*. They never have both connections running over the same exact wire-they can't-RS-232/422 TX data lines can't receive data, and RS-232/422 RX data lines can't transmit data.

Some of the older chartplotters, which were designed before DSC-capable VHFs were common, can not accept the DSC-generated NMEA LAT/LON data and plot it on the screen. The software in them doesn't support that function. _This is probably why the manual emphasizes this point-that it can supply the radio with LAT/LON position data is assumed._



floatsome said:


> I know that (taught the course for several years), but I did not see in the literature that the 640 is able to supply the radio with the host boat's position data in order to transmit the boat's position digitally, unless I missed something. It only talked about the 640 receiving position data from other boats via the radio receiver. Maybe that single NMEA link is two-way, and the literature simply did not specify it, or I missed it.


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## floatsome (Jul 5, 2008)

Mystery partly resolved: the manual says nothing about how the 640 physically connects to an NMEA network, but this does: http://www8.garmin.com/manuals/GPSMAP620_InstallationInstructions.pdf. The 640 has both TX/RX connections, but they appear to be made through the marine-mount bracket. I can't tell if there is a connector in the 640 that mates with a connector in the bracket and the user wires the network into the bracket's cable, or if there are user-accessible NMEA ports on the 640 itself.


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## sailingdog (Mar 19, 2006)

It looks like the bracket acts as a cable connection, so I doubt there's a separate NMEA 0183 interface on the unit.


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## arisatx (Sep 2, 2004)

sailingdog said:


> It looks like the bracket acts as a cable connection, so I doubt there's a separate NMEA 0183 interface on the unit.


Got one! There's a 24 "pin" connector on the bottom of the 640 that mates with the contacts on the mount. Having owned the 276c for many years now and enjoying the portability between car, bike and boat (incl charter boats), I have been waiting for this new gen 640. The user interface and the touch screen are taking some time to get used to. And it appears that if you want XM Radio or XM Weather, you have to connect the XM antenna via USB port (not the aforementioned 24 pin connector to the NMEA 0183 interface) so it does not seem to lend itself to a "permanent" xm install.

I have not yet obtained the g2Vision SD card so can't comment on that. It won't replace a full chartplotter onboard, IMHO, but seems like a good successor to the 276c line.

Oh and if you hunt around, you can find the units for around $980 as I recall.


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## floatsome (Jul 5, 2008)

arisatx said:


> ...it appears that if you want XM Radio or XM Weather, you have to connect the XM antenna via USB port (not the aforementioned 24 pin connector to the NMEA 0183 interface) so it does not seem to lend itself to a "permanent" xm install.


Very helpful - thanks. About the XM connection: would a little modification with a Dremmel tool give access to the USB port while the unit is mounted in the bracket?

I did that years ago with my old 76C bracket, and the modification has been working very well over the years (allows both power plug and USB connection while in the bracket). It exposes the wiring to weather risk, however, since of course the little black rubber plug has long since vanished.



arisatx said:


> ...won't replace a full chartplotter onboard...


I agree, but what is your rationale for this comment? It seems to me that larger consumer-grade chartplotters tend to be just bigger versions of the 76 and 276 families, without features that make it easy to modify waypoints and routes the way one can on a laptop using Mapsource or other PC nav programs. Professional chartplotters have many more features that make true electronic plotting and planning very easy, but that's still out of the league of most of us pleasureboaters, I suspect. And of course bigger consumer-grade chartplotters allow integrated radar/electronic chart display, which the 640 does not. (By "chartplotter" I mean a GPS display unit dedicated to the purpose, as opposed to a laptop/desktop configure for chartplotting).


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## arisatx (Sep 2, 2004)

Floatsome:

re: XM connection via USB, you won't need to pull out the Dremel to perform surgery on the mount. USB can be connected when the 640 is in the mount - it's just another connector dangling there, in addition to an XM radio audio out - wish they could've incorporarted this all into the multi-connector.

re: my comment about not replacing a full chart plotter, it doesn't overlay radar, it's not N2K - but as you point out, then we're in another price category.

But for it's purpose, I'm pretty happy with the 640 so far.


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## gtod25 (Aug 5, 2000)

*I got to play with Garmin 620 yesterday.....*

Nice, very nice. I expect to see the 640 soon, but the screen resolution is excellent and I love the touch screen. I have been using a 5210 touch screen for over a year and have had no problems. I think the 640 will give the 545 a run for its money especially for someone who wants a portable battery unit.

Contrary to a previous post the 640 is NOT designed to be permanently mounted and it will kill off the 478, which is already being discounted.

The 640 has build in charts for the US and can only use "BlueChart g2 VISION" cards and NOT BlueChart or BlueChart G2 charts as previously stated also.


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## floatsome (Jul 5, 2008)

gtod25 said:


> The 640 has build in charts for the US and can only use "BlueChart g2 VISION" cards and NOT BlueChart or BlueChart G2 charts as previously stated also.


Looks like the 640 has preloaded Canada and US coverage in BlueChart g2:" "comes ready to go with preloaded BlueChart® g2 data and City Navigator NT road maps for North America ... optional BlueChart g2 Vision cards" https://buy.garmin.com/shop/shop.do?cID=148&pID=14898.

1. So _BlueChart g2 Vision _appears to be optional (each subregion card costs about $300, I think). 
2. Looks like each _BlueChart g2 _sub-region requires an unlock code that appears to cost about $200 -- does the box price include one unlock code for one subregion?
3. And does the box price include one unlock code which unlocks all the _City Navigator NT_ maps for all of Canada and US?


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## gtod25 (Aug 5, 2000)

*Charts for 640*

As I said I was using the 620 which has only the world basemap (i.e. no detail). Garmin states thet the 640 has built in BlueChart® g2 data for North America. If it is the same as the 545 (which I believe it is) no codes are needed. The 545 series the charts only cover the USA and not Canada or Mexico.

Outside this area you need to buy BlueChart g2 Vision at $310+/- each.

I have no knowledge of City navigator as I see no reason for putting a $1000 device in a car, when you can get a Nuvi for $100.


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## sailingdog (Mar 19, 2006)

floatsome said:


> Looks like the 640 has preloaded Canada and US coverage in BlueChart g2:" "comes ready to go with preloaded BlueChart® g2 data and City Navigator NT road maps for North America ... optional BlueChart g2 Vision cards" https://buy.garmin.com/shop/shop.do?cID=148&pID=14898.
> 
> 1. So _BlueChart g2 Vision _appears to be optional (each subregion card costs about $300, I think).


yes, but the g2 vision has some information and photos that the G2 pre-loaded charts don't.



> 2. Looks like each _BlueChart g2 _sub-region requires an unlock code that appears to cost about $200 -- does the box price include one unlock code for one subregion?


Should include the unlock code for one sub-region to load the charts into two GPS units. Garmin provides you the ability to use the charts you unlock on TWO separate units IIRC.


> 3. And does the box price include one unlock code which unlocks all the _City Navigator NT_ maps for all of Canada and US?


Yes, Canada and US maps are under a single unlock code, again, believe they give you the option of loading them onto TWO devices.


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## floatsome (Jul 5, 2008)

floatsome said:


> Is NMEA 0183 enough these days, now that NMEA 2000 is out?


What are thoughts about this issue with the Garmin 640? I'm refitting a new to us boat, and looking at starting over with the instruments, but budget is also an issue so cannot replace everything. But I would prefer not to spend this much on a GPS receiver that is only 0183 if the future is 2000 should I get a new VHF radio, for example.


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## floatsome (Jul 5, 2008)

How weather resistant are the 640 and 478? Can they be mounted on the steering pedestal of a 27 foot sailboat in the open for coastal cruising?


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## sailingdog (Mar 19, 2006)

IIRC, both are rated at IPX7 for water resistance.. That means they can withstand submersion for 30 minutes at one meter of depth... if you have more water than that at the helm of a 27' sailboat, you're doing something wrong. 


floatsome said:


> How weather resistant are the 640 and 478? Can they be mounted on the steering pedestal of a 27 foot sailboat in the open for coastal cruising?


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## floatsome (Jul 5, 2008)

*Two hangups*

1. I understand IPX7, but I wonder about all the electrical plug-in connections on the 640's bracket (power, 0183), and the ability of the bracket to withstand weather. I can't physically see a 640.

2. Another issue: planning on a PC. If the BlueChart G2 charts come preloaded on the 640, how does one view the charts on a PC, to use the PC to plan ahead and upload waypoints to the 640? Or does Garmin allow a user to copy BlueChart G2 charts from the 640 onto a card or via USB into the PC, so a user can plan on the PC using MapSource? Or, does a user have to purchase a BlueChart G2 CD and get unlock codes for use on the PC?


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## sailingdog (Mar 19, 2006)

Yes, the bracket is part of the unit and should withstand the same conditions.  Garmin usually gold plates their electrical connectors so that corrosion isn't an issue for them.



floatsome said:


> 1. I understand IPX7, but I wonder about all the electrical plug-in connections on the 640's bracket (power, 0183), and the ability of the bracket to withstand weather. I can't physically see a 640.


Most of these questions would be answered in the product's manual, which is easily available to anyone on Garmin's website. *I would suggest you download the manual you provided a link to previously and read it before asking basic questions it can answer.* 

*The manual discusses copying the pre-loaded charts, waypoints, tracks and routes to an SD card on page 29. *The MapSource software can then read the SD card, provided you have a SD card reader...

You can create/edit/archive waypoints and routes on a Windows-PC running MapSource. You can archive tracks using it as well.



> 2. Another issue: planning on a PC. If the BlueChart G2 charts come preloaded on the 640, how does one view the charts on a PC, to use the PC to plan ahead and upload waypoints to the 640? Or does Garmin allow a user to copy BlueChart G2 charts from the 640 onto a card or via USB into the PC, so a user can plan on the PC using MapSource? Or, does a user have to purchase a BlueChart G2 CD and get unlock codes for use on the PC?


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## floatsome (Jul 5, 2008)

sailingdog said:


> *I would suggest you download the manual you provided a link to previously and read it before asking basic questions it can answer.* *The manual discusses copying the pre-loaded charts, waypoints, tracks and routes to an SD card on page 29. *


The manual says the user can copy the _basemap_, not the e-charts.


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## sailingdog (Mar 19, 2006)

Yes, but for planning purposes, do you need the actual e-charts. If you do, then you may need to buy a BlueChart DVD... however, for most planning purposes, the basemap is probably all you really need. You can always check the waypoints and routes once they're downloaded into the GPS. Besides, this is a portable unit, not a fixed mount, and you can have it with you when doing the planning and double check things on the 640 as you do it.


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## floatsome (Jul 5, 2008)

sailingdog said:


> Yes, but for planning purposes, do you need the actual e-charts.


Yes, I do not use basemaps for my planning.



sailingdog said:


> If you do, then you may need to buy a BlueChart DVD...


You may be right about having to buy a second set of charts for the laptop, but I find it hard to believe that Garmin does not have a better solution. In the past, we loaded our charts from DVD to laptop, and then laptop to chartplotter, and their owner verification system allowed the registered user to have the charts in both places: laptop for planning (since nRoute is not the slickest software for moving map under way and other moving map programs cannot use BlueCharts) and the registered Garmin chartplotter for navigating under way. Now... ?


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## sailingdog (Mar 19, 2006)

The older units, that did not have the entire set of coastal/inland charts pre-loaded did come with a Bluechart DVD. However, they were far more expensive, in that you had to unlock each region separately. You didn't need to use nRoute, as MapSource would work as a real-time chartplotter on any maps you had unlocked.



floatsome said:


> You may be right about having to buy a second set of charts for the laptop, but I find it hard to believe that Garmin does not have a better solution. In the past, we loaded our charts from DVD to laptop, and then laptop to chartplotter, and their owner verification system allowed the registered user to have the charts in both places: laptop for planning (since nRoute is not the slickest software for moving map under way and other moving map programs cannot use BlueCharts) and the registered Garmin chartplotter for navigating under way. Now... ?


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## Yamsailor (Jun 7, 2006)

ok- I need some clarifications:

1) On the 640, are all the US Charts unlocked or is it by sub-region?

2) Can you load the charts onto a laptop and plan out routes and then download the routes back into the unit?

3) How does one update the charts? By sub-region or do you update the entire chart base?


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## floatsome (Jul 5, 2008)

sailingdog said:


> MapSource would work as a real-time chartplotter on any maps you had unlocked.


? - I thought MapSource was simply a BlueChart map viewer that would only allow the user to plan routes and build/maintain waypoints, but not display moving map real time with positioning from a GPS receiver?


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## floatsome (Jul 5, 2008)

Yamsailor said:


> ok- I need some clarifications:
> 1) On the 640, are all the US Charts unlocked or is it by sub-region?
> 2) Can you load the charts onto a laptop and plan out routes and then download the routes back into the unit?
> 3) How does one update the charts? By sub-region or do you update the entire chart base?


All good questions that I am still trying to figure out. Re your #2: I just learned about what seems to be new Garmin software called _HomePort_: "Use your existing BlueChart® preprogrammed card, or transfer the preloaded maps² directly from your chartplotter to an SD™ card. Then simply plug the card into your computer's card reader to start planning your voyage." https://buy.garmin.com/shop/shop.do?pID=64242 But, the devil is always in the details, and I can't sort out in my mind exactly how this works if one buys a preloaded receiver like the 640.


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## Yamsailor (Jun 7, 2006)

floatsome said:


> All good questions that I am still trying to figure out. Re your #2: I just learned about what seems to be new Garmin software called _HomePort_: "Use your existing BlueChart® preprogrammed card, or transfer the preloaded maps² directly from your chartplotter to an SD™ card. Then simply plug the card into your computer's card reader to start planning your voyage." https://buy.garmin.com/shop/shop.do?pID=64242 But, the devil is always in the details, and I can't sort out in my mind exactly how this works if one buys a preloaded receiver like the 640.


Anybody at Garmin we can contact so we can get something in writing? Any suggestions?


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## sailingdog (Mar 19, 2006)

Yamsailor said:


> ok- I need some clarifications:
> 
> 1) On the 640, are all the US Charts unlocked or is it by sub-region?


On the 640, the US Coastal charts are all unlocked and pre-loaded.



> 2) Can you load the charts onto a laptop and plan out routes and then download the routes back into the unit?


No, you can't load the charts onto a laptop. However, if you have their software, you can plan out routes, waypoints, etc and load them into the unit.

You can use another software package to do the route-planning and often safe the results in a format the Garmin software can use to transfer the routes and waypoints to the 640.



> 3) How does one update the charts? By sub-region or do you update the entire chart base?


IIRC, the 640 is updated for about $75 with a $200 deposit by ordering an update chart set from Garmin which is shipped on a memory card. The $200 deposit is refunded when you return the card.


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## Yamsailor (Jun 7, 2006)

sailingdog said:


> On the 640, the US Coastal charts are all unlocked and pre-loaded.
> 
> No, you can't load the charts onto a laptop. However, if you have their software, you can plan out routes, waypoints, etc and load them into the unit.
> 
> ...


So Garmins new route planning software is what you would use on a laptop--correct?


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## eherlihy (Jan 2, 2007)

*478 Experience*

In the hope of addressing some confusion, here is my experience from owning a GPSmap 478 (non-touchscreen predecessor of the GPSmap 640);

The unit includes ALL the US Costal Charts in ROM. It also includes US road maps (in great detail) in ROM. Also included in the box is a Bluechart basemap DVD. This DVD includes all the current detailed Garmin charts. However, you need an unlock code to enable each specific region. You really cannot do coastal route planning on your PC with the included software license. The basic chart that the license unlocks does not provide ATON for harbors or channels.

Garmin makes a lot of money (I suspect the majority) selling charts. Think of these chart plotters as razors, and the charts (and updates) as razor blades.

As SD pointed out, you can update the included charts for an area by buying a Garmin chart (on a Garmin memory card) for that area (~$160), loading the updated chart into the unit, and returning the card to Garmin. Garmin will refund $70 (I believe), so that your net cost of updating ONE area is ~$90. I have not done so - yet.

There are some models of Garmin chart plotters for which a lifetime (of the product - as defined by Garmin) update of the included charts is available for ~$130.00 Neither the GPSmap 478, not the 640 qualify for this update service.

That said, I LOVE my GPSmap 478! I bought it when it first came out (2006) for about $950. Because I sail on OPB, this is the one chart plotter that I know what ALL the buttons do. I find that it has more, and better features than most of the chart plotters that are installed on the boats that I am sailing. I have also benefitted that in the event of an on board electrical failure (this happened) the GPSmap continues to function. Should I ever have to ditch, I can carry this unit with me.

Regarding the comparison to automotive GPS units, I find that the display of the GPSmap gives far more useful data than the built-in unit of my wife's 2009 Hundai Azera. I configured the data fields to show me actual speed (I know that my speedometer consistently reads 3mph faster than actual), ETE Next Turn, Distance Next Turn, and ETA. All of these fields are user selectable from about 80 different telemetry calculations. When I used to travel extensively for work, this unit was always with me, and was worth the price in lack of frustration in finding (or getting close to) customer sites.

Occasionally, the unit would screw up in finding a specific address, or the BEST route to my destination. For example, every time that I travel to my sister's condo in South Ft Myers, FL, from the north, it directs me to get off RT 75 in FT Myers, and travel route 41 South through all the stoplights. I ignore the unit, and get off 75 two exits south of the original directions. This is what I would call "local knowledge."

To me, the difference between the 478 and 640 is that the 640 has a larger TOUCH screen, and that the unit will automatically switch between Auto and Marine mode (I do not like this, as I will sometimes look at a mooring field, or canal, from my car and wonder what the draft is. I simply switch to Marine mode, and have my answer. I'm not sure that youcan do this with the 640).

As for water resistance, I can vouch that my 478 was exposed to about 5 hours of road spray while mounted on my motorcycle, travelling through torrential rain, on my way from Key West to St George SC. This did not affect the unit, or it's connector at all.

HTH!!

- Ed


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## Yamsailor (Jun 7, 2006)

Yamsailor said:


> ok- I need some clarifications:
> 
> 1) On the 640, are all the US Charts unlocked or is it by sub-region?
> 
> ...


OK--I received an e-mail from Garmin with the following responses:

1) All the US Charts are unlocked;

2) The new planning software uses the charts and can be used for planning both for G2 and G2 vision charts;

3) Charts are updated once per year at a current cost of $75 for all of the US G2 charts NOT the G2 Vision.

G2 Vision Charts are purchased by sub-region and updates are purchased by sub-region. If you do not use the G2 Vision charts, I think it is a pretty nice GPS and the Cost/Benefit seems somewhat reasonable.


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## ereuter (Aug 31, 2006)

Hi everyone-
This thread has been dormant for a while. Hope nobody minds me churning it up.

I just bought the 640 and have a couple of questions/comments. I called Garmin tech support, but the tech who helped me didn't know what VMG means.

It appears that the 640 will not display VMG to a waypoint unless you have a wind instrument connected. This doesn't make any sense, and I hope I'm wrong. I had a 478 (and many previous Garmin chartplotters) that did this, and I'm totally confused as to why they would omit this. It's a trivial calculation. The Garmin support person told me that VMG was actually removed from the 478, and I'd have lost it if I'd done a software update.

Second, the optional bar across the screen that shows data from a wind instrument is cool, but Garmin doesn't seem to sell a NMEA 0183 wind instrument. Could anyone recommend a headless instrument or a converter from NMEA 2000 to 0183?

Other than the VMG gripe, this thing is really cool. I'm considering the flush mount, but it's hard to cut a hole that big in the bulkhead!

Thanks-
Eric


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## LinekinBayCD (Oct 19, 2009)

Eric,

The tech person may have ment a heading sensor rather than a wind insturment. Can't imagine you would need a wind insturment. I notice that a heading reading was not available on my Garmin 3006 when I first got it. They do give you a compass display from which you can geat the heading degrees though so I have no idea why they elminated the heading degree reading. I don't really need / use the VMG function, not a racer.

Rather than cutting a big hole in the bulkhead why not mount on a piece of teak with a small hole for the wires?

Joe


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## ereuter (Aug 31, 2006)

Joe- 
Thanks for the mounting suggestion. Unfortunately, it requires 3.5" of depth for the enclosure. I'll make do with the surface mount for now. It's just in danger of getting wrecked during races.

Eric


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## TakeFive (Oct 22, 2009)

In case anyone is interested in this GPS model, WestMarine has it on sale for $799. Their website also has a 10% off sale. Although their fine print says that the 10% off is not good on "select Garmin" items, the website did give me 10% off this item, for a net price of $719.

The 10% off sale ends today.


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