I've been doing quite a bit of PHRF racing recently. I think I could improve my finishes if I had a good GPS handheld that could tell me my VMG to a waypoint or along a magnetic course. I've been looking at GPSs and very few even mention VMG in their marketing info. Does anyone have suggestions or any good or bad experience trying to maximize VMG with a GPS?
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GPS Handheld & VMG
My GPS Map 76S gives the following: VMG, Total Avg Speed, Speed, Moving Avg Speed, Maximum Speed Now if I just knew the difference between them, I'd be a little smarter....
My GPS Map 76S gives the following: VMG, Total Avg Speed, Speed, Moving Avg Speed, Maximum Speed Now if I just knew the difference between them, I'd be a little smarter....
Mine does
I have the Magellan Marine GPS with plotter. It gives a VMG reading, as well as lots of other great features. I'm very happy with it.
I have the Magellan Marine GPS with plotter. It gives a VMG reading, as well as lots of other great features. I'm very happy with it.
VMG
I've noticed most of the newer model hand helds have a VMG feature. My Garmin GPS 76, ($199 at Boat U/S) has VMG plus other features like tack or turn alarm, off course, etc. VMG needs a destination to work, but you probably knew that. I think VMG knowledge is critical when racing. I might tell you that there is VMG card or chart (not electronic) that can be used also, I believe it's based on polar charts. But that's way to complicated for me.
I've noticed most of the newer model hand helds have a VMG feature. My Garmin GPS 76, ($199 at Boat U/S) has VMG plus other features like tack or turn alarm, off course, etc. VMG needs a destination to work, but you probably knew that. I think VMG knowledge is critical when racing. I might tell you that there is VMG card or chart (not electronic) that can be used also, I believe it's based on polar charts. But that's way to complicated for me.
RE:Need help finding a GPS for maximizing VMG
Garmin has several models. As you mentioned most feature tables don't list VMG. I ended up reading the user manuals (available online at www.garmin.com) The ETREX Legend (retail $200) has VMG as dies the GPS 12 and 12XL. They alsohave several other good features, like displaying how far you are off course
Garmin has several models. As you mentioned most feature tables don't list VMG. I ended up reading the user manuals (available online at www.garmin.com) The ETREX Legend (retail $200) has VMG as dies the GPS 12 and 12XL. They alsohave several other good features, like displaying how far you are off course
Velocity Made Good
If your waypoint is at 0 degrees and your course over ground is 0 degrees at 6 knots, then your vmg is 6 knots. If your course is 90 degrees, the vmg = 0 (you'll never get there}. I guess that if your cog is 180 degrees, your vmg = -6 knots. Bill
If your waypoint is at 0 degrees and your course over ground is 0 degrees at 6 knots, then your vmg is 6 knots. If your course is 90 degrees, the vmg = 0 (you'll never get there}. I guess that if your cog is 180 degrees, your vmg = -6 knots. Bill
VMG, other terms
VMG, or "velocity made good" is speed made in the direction of your destination. VMG is important when the boat's nose is not pointed directly at your destination, which occurs: 1. On a beat. The direction to your destination is in the no-go zone. You might ask yourself, "is it better to pinch, go slower, and point more directly; or is it better to bear off a bit, go faster, even though it means going a little farther?" The answer is: whichever method produces the highest VMG. 2. On a run. You could point the boat directly at your destination, but what if you could get there faster by gibing from one broad reach to another? VMG again gives the answer. On a reach, you're already fast and you're heading directly at where you're going. On a reach laying your objective, SOG and maximum VMG are the same. Your GPS can only calculate VMG if it has a destination, i.e. you are sailing to a waypoint. If you're a trigonometry whiz, VMG is roughly SOG X cosine(Heading - Bearing), or something like that. SOG is Speed over Ground, Bearing is the bearing to your destination, and heading is your wake course. I think it's tough to get this information from a GPS, unless your helmsman is very skilled at holding a course long enough to measure VMG for a given wind angle. That's why people tend to use polar diagrams instead. Some other definitions: 1. Average speed: probably the average speed from the moment you turned on the GPS, or the moment you started your route, until now. 2. Moving average speed: your average speed over the last X seconds, X being determined by the person who wrote the moving average calculations into the GPS's software. It's a lot of stuff, hope it helps someone. Paul sv Escape Artist h336
VMG, or "velocity made good" is speed made in the direction of your destination. VMG is important when the boat's nose is not pointed directly at your destination, which occurs: 1. On a beat. The direction to your destination is in the no-go zone. You might ask yourself, "is it better to pinch, go slower, and point more directly; or is it better to bear off a bit, go faster, even though it means going a little farther?" The answer is: whichever method produces the highest VMG. 2. On a run. You could point the boat directly at your destination, but what if you could get there faster by gibing from one broad reach to another? VMG again gives the answer. On a reach, you're already fast and you're heading directly at where you're going. On a reach laying your objective, SOG and maximum VMG are the same. Your GPS can only calculate VMG if it has a destination, i.e. you are sailing to a waypoint. If you're a trigonometry whiz, VMG is roughly SOG X cosine(Heading - Bearing), or something like that. SOG is Speed over Ground, Bearing is the bearing to your destination, and heading is your wake course. I think it's tough to get this information from a GPS, unless your helmsman is very skilled at holding a course long enough to measure VMG for a given wind angle. That's why people tend to use polar diagrams instead. Some other definitions: 1. Average speed: probably the average speed from the moment you turned on the GPS, or the moment you started your route, until now. 2. Moving average speed: your average speed over the last X seconds, X being determined by the person who wrote the moving average calculations into the GPS's software. It's a lot of stuff, hope it helps someone. Paul sv Escape Artist h336
I love mine!
Im useing the garmin 176c. I love it. its small enough to move from boat to boat, i race on two and cruise on two. so i take it with me. It is also a moving map in color. This techology is wonderful. It also allows you to tell whats going on with tide or current drift. ETA,Tides, routing,mag and true headings( we usually steer with the gps and dont bother to convet data. you can set up screens with just the data you want. We race alot from tampa and ours it set up with speed, vmg, bearing and track. so we see quickly what is happenig on all fronts. it is by far the best tool we have. It does not take the place of a good knot meter though, becase the slight delay in upgrade does not react as quick as a good speedo. the other wonderful tool is apparent wind indicators. and as long as your dreaming a kvh sail comp or tick tac sailing computer is wonderful. they will keep track and show headers and lifts so it really makes the helmsmans job a lot easer. This list should only take up a few boating units (thousans dollar bills). The garmin line has been great for me, i also have a handheld 76 garmin that does most of the same functions just a lot smaller screen.
Im useing the garmin 176c. I love it. its small enough to move from boat to boat, i race on two and cruise on two. so i take it with me. It is also a moving map in color. This techology is wonderful. It also allows you to tell whats going on with tide or current drift. ETA,Tides, routing,mag and true headings( we usually steer with the gps and dont bother to convet data. you can set up screens with just the data you want. We race alot from tampa and ours it set up with speed, vmg, bearing and track. so we see quickly what is happenig on all fronts. it is by far the best tool we have. It does not take the place of a good knot meter though, becase the slight delay in upgrade does not react as quick as a good speedo. the other wonderful tool is apparent wind indicators. and as long as your dreaming a kvh sail comp or tick tac sailing computer is wonderful. they will keep track and show headers and lifts so it really makes the helmsmans job a lot easer. This list should only take up a few boating units (thousans dollar bills). The garmin line has been great for me, i also have a handheld 76 garmin that does most of the same functions just a lot smaller screen.
Will sell mine
I know the forums aren't for dealing, but I have a Garmin 76 that I have barely used and need to go to a 76s (as long as we are on the subject.) Discount price, jdawson229@yahoo.com if interested.
I know the forums aren't for dealing, but I have a Garmin 76 that I have barely used and need to go to a 76s (as long as we are on the subject.) Discount price, jdawson229@yahoo.com if interested.
Garmin 72
Anyone looking for a bargain might want to get the 72. I have it; it has almost all of the features of the 76, and it will give GMG. It doesn't have the mapping features of the 76, though. If I hadn't been trying to save money, I would have gone with the 76c.
Anyone looking for a bargain might want to get the 72. I have it; it has almost all of the features of the 76, and it will give GMG. It doesn't have the mapping features of the 76, though. If I hadn't been trying to save money, I would have gone with the 76c.
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