Jim recently suggested using a GPS system for determining speed. For those of you who have such systems, which do you suggest are the best? Do hand held units work well? I sail on a lake and do not need one to find my way, but it would be nice to measure how fast I am going. Thanks Alan
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Boat speed,Lakes & GPS
Alan ,You can get a Hand Gps That will not only be handy for speed on your boat,but I also use my Hand gps in my car,it has street maps and shows the lakes and rivers. Only thing is a gps shows land speed,if you are in a flow of water it will not show speed of water to boat,that is some times handy for knowing if you have all working and trimed well for a sailboat,most lakes have little if any flow so land speed is AOK
Alan ,You can get a Hand Gps That will not only be handy for speed on your boat,but I also use my Hand gps in my car,it has street maps and shows the lakes and rivers. Only thing is a gps shows land speed,if you are in a flow of water it will not show speed of water to boat,that is some times handy for knowing if you have all working and trimed well for a sailboat,most lakes have little if any flow so land speed is AOK
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- Jan 22, 2008
- 519
gps on lakes
I have a Garmin eTrex, which is a small $100+ handheld unit. It is waterproof and floats. I attach it to the top of the centerboard trunk of my daysailer (yellow unit in picture), with a hook and loop, (velcro) fastener. It not only acts as a repeater for my regular bulkhead mounted compass which is sometimes blocked by someone sitting in front of it, and a speedo providing feedback to technique, but with waypoints such as the launching dock entered in, will give me ETA and distance to, information. More importantly, after I get back home and upload my track, and match it to a digital map of the lake, it shows my track on map. It is a great addition to my log, but also allows me to analyze my sailing day. As an example I noted that my boat was pointing exceptionally well on a particular run, 25 degrees off the wind. I had my doubts that this was accurate, and assumed that inspite of excellent pointing, I was making excessive leeway to compensate, until I was able to look at the track on a chart and confirm that indeed the boat was tracking exceptionally well. Another situation where a GPS outshines a compass is that it can give you directions relative to true north, so that no adjustment is required for leeway or magnetic declination, when relating directly to a chart. Of course it gives you coordinate information as to exactly where you are now, which, when transferred to a chart, or topo map even, (if your lake is not represented by a chart) can be plotted directly. We once navigated through shoals for a couple of miles by using the GPS plot every few minutes to monitor our position through the shallow water marked by submerged rocks on the chart. We threaded our way using true bearings taken from the chart and responded to the feedback of the GPS. No compass would have allowed us to be that accurate with our navigation.
I have a Garmin eTrex, which is a small $100+ handheld unit. It is waterproof and floats. I attach it to the top of the centerboard trunk of my daysailer (yellow unit in picture), with a hook and loop, (velcro) fastener. It not only acts as a repeater for my regular bulkhead mounted compass which is sometimes blocked by someone sitting in front of it, and a speedo providing feedback to technique, but with waypoints such as the launching dock entered in, will give me ETA and distance to, information. More importantly, after I get back home and upload my track, and match it to a digital map of the lake, it shows my track on map. It is a great addition to my log, but also allows me to analyze my sailing day. As an example I noted that my boat was pointing exceptionally well on a particular run, 25 degrees off the wind. I had my doubts that this was accurate, and assumed that inspite of excellent pointing, I was making excessive leeway to compensate, until I was able to look at the track on a chart and confirm that indeed the boat was tracking exceptionally well. Another situation where a GPS outshines a compass is that it can give you directions relative to true north, so that no adjustment is required for leeway or magnetic declination, when relating directly to a chart. Of course it gives you coordinate information as to exactly where you are now, which, when transferred to a chart, or topo map even, (if your lake is not represented by a chart) can be plotted directly. We once navigated through shoals for a couple of miles by using the GPS plot every few minutes to monitor our position through the shallow water marked by submerged rocks on the chart. We threaded our way using true bearings taken from the chart and responded to the feedback of the GPS. No compass would have allowed us to be that accurate with our navigation.
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Mounting a Handheld GPS
Most hand held GPS's have a mount for bicycle handle bars. These work great on your binnacle.
Most hand held GPS's have a mount for bicycle handle bars. These work great on your binnacle.
Lowrance iFinder
I have a Lowrance iFinder. Have used Garmin, Magellan, and Delorme units of various descriptions in the past, and like the features and operation of the iFinder best. Acquires signals quickly and holds on to 'em. If you press, I believe, the ENTER button three or four times in succession, it displays what looks like an analog speedometer that you can set for 10mph max, giving a very effective quick-glance speedometer. Watching mine taught me mass quantities about the finer points of trimming sail on my Mac25. iFinder has excellent selection of accessories, too. Unit itself is not overly expensive, and is available at Wally World and such, but addons make it comparably priced to other units. Also has a great anchor alarm feature and hooks up to my VHF for DSC location data transmission, in case I ever get off of my little lake into bigger waters.
I have a Lowrance iFinder. Have used Garmin, Magellan, and Delorme units of various descriptions in the past, and like the features and operation of the iFinder best. Acquires signals quickly and holds on to 'em. If you press, I believe, the ENTER button three or four times in succession, it displays what looks like an analog speedometer that you can set for 10mph max, giving a very effective quick-glance speedometer. Watching mine taught me mass quantities about the finer points of trimming sail on my Mac25. iFinder has excellent selection of accessories, too. Unit itself is not overly expensive, and is available at Wally World and such, but addons make it comparably priced to other units. Also has a great anchor alarm feature and hooks up to my VHF for DSC location data transmission, in case I ever get off of my little lake into bigger waters.
Garmin GPS Map 76
I just bought my GPS today. I had decided on the Garmin 76 GPS until I got to the store. When I was in there the sales rep. showed me the differences between a bunch of units. The Garmin 76 GPS is a nice unit, but the Garmin GPS Map 76 is much nicer. The first thing that sold me on this unit is the built in base map. It is nice to have that information. Another nice feature is that I can use the blue charts program. The unit was $100 more than I was going to spend, but I think that I would have regretted not getting it if I had gotten the Garmin 76 GPS. I have played around with it and I am really impressed. It will take a while to learn it but I am already doing the basic functions. Now I can't wait to get on the water!
I just bought my GPS today. I had decided on the Garmin 76 GPS until I got to the store. When I was in there the sales rep. showed me the differences between a bunch of units. The Garmin 76 GPS is a nice unit, but the Garmin GPS Map 76 is much nicer. The first thing that sold me on this unit is the built in base map. It is nice to have that information. Another nice feature is that I can use the blue charts program. The unit was $100 more than I was going to spend, but I think that I would have regretted not getting it if I had gotten the Garmin 76 GPS. I have played around with it and I am really impressed. It will take a while to learn it but I am already doing the basic functions. Now I can't wait to get on the water!
Matt ....
The 76 has bouys and markers preprogrammed almost anywhere you go. You may regret having to but those blue charts. Add the only extra $100 to the chart prices and .......... They gotcha
The 76 has bouys and markers preprogrammed almost anywhere you go. You may regret having to but those blue charts. Add the only extra $100 to the chart prices and .......... They gotcha
They pretty much all work the same
all GPS receivers lock on to the same satellites and all will read the same position (within the tolerance of the measurement). The only difference is in the frills. Of course, the newer ones offer more frills and are more user-friendly for less money. My first and only GPS (a handheld Magellan GPS 315 with the B&W LCD screen) is still going strong. It's connected to the 12V house battery and a Raymarine tillerpilot via the NMEA port. BTW it's not hard to figure current with a GPS...just stop the boat and drift for a minute (as long as you have room). Peter H23 "Raven"
all GPS receivers lock on to the same satellites and all will read the same position (within the tolerance of the measurement). The only difference is in the frills. Of course, the newer ones offer more frills and are more user-friendly for less money. My first and only GPS (a handheld Magellan GPS 315 with the B&W LCD screen) is still going strong. It's connected to the 12V house battery and a Raymarine tillerpilot via the NMEA port. BTW it's not hard to figure current with a GPS...just stop the boat and drift for a minute (as long as you have room). Peter H23 "Raven"
GPS comments.....
1. it is possible to pilot very accurately with only a compass, watch and a chart. If a gps is your only navigational tool, get two of them....so you have a back up. 2. Don't stare at the chartplotter map while helming. I find steering is easier and safer using the compass or hiway mode, occassionally checking the map for reference. 3. The basic map on the garmin 76 chartplotter is worthless for navigation, so if you don't purchase the blue chart.... there's no point. just get the gps and the points of interest CD for your computer which is way, way easier for route planning than trying to do it on the handheld unit. That's $200 for the gps and $50 for the CD as opposed to $300 for the 76map and $140 for the chart. 4. get a gps that is designed for marine use. It should be able to be configured for statute miles, kilometers or nautical miles. True or magnetic, It should be connectable to other electronic devices, like autopilots. It should offer many data fields such as ETA, distance to waypoint, velocity made good, etc. the Garmin gps 76 has all these features and more.
1. it is possible to pilot very accurately with only a compass, watch and a chart. If a gps is your only navigational tool, get two of them....so you have a back up. 2. Don't stare at the chartplotter map while helming. I find steering is easier and safer using the compass or hiway mode, occassionally checking the map for reference. 3. The basic map on the garmin 76 chartplotter is worthless for navigation, so if you don't purchase the blue chart.... there's no point. just get the gps and the points of interest CD for your computer which is way, way easier for route planning than trying to do it on the handheld unit. That's $200 for the gps and $50 for the CD as opposed to $300 for the 76map and $140 for the chart. 4. get a gps that is designed for marine use. It should be able to be configured for statute miles, kilometers or nautical miles. True or magnetic, It should be connectable to other electronic devices, like autopilots. It should offer many data fields such as ETA, distance to waypoint, velocity made good, etc. the Garmin gps 76 has all these features and more.
Not all GPS' drive pilots
Joe, I found that the old Garmin 12 hand held unit does the job. Route planning is easy by uploading them from a lap top running most navigation softwares, given that not all lakes are mapped on electronic charts. However, I found that Garmin units can not be interfaced with Navico or Simrad auto pilots since they don't send a route-waypoint alarm on the NMEA string.
Joe, I found that the old Garmin 12 hand held unit does the job. Route planning is easy by uploading them from a lap top running most navigation softwares, given that not all lakes are mapped on electronic charts. However, I found that Garmin units can not be interfaced with Navico or Simrad auto pilots since they don't send a route-waypoint alarm on the NMEA string.
Boat speed
Alan, Keep in mind that stand alone GPS units will give you speed over ground (as opposed to boat speed over water), which can be significantly different in current.
Alan, Keep in mind that stand alone GPS units will give you speed over ground (as opposed to boat speed over water), which can be significantly different in current.
Joe, thanks for refreshing post.....
Not to be critical about post which say... "I got model X of brand Z" and you should too, but I found Joe's post full of honest objectivity. I have wondered for some time if a handheld plotter made enough sense... and Joe's post kicked me off the fence to draw the conclusion that one is not in my near or perceived future. Thanks Joe.
Not to be critical about post which say... "I got model X of brand Z" and you should too, but I found Joe's post full of honest objectivity. I have wondered for some time if a handheld plotter made enough sense... and Joe's post kicked me off the fence to draw the conclusion that one is not in my near or perceived future. Thanks Joe.
Bert, Stop. The GPS system has no way of knowing
what you are driving. A GPS computer can only tell you your speed over the bottom (ground). It is your job to figure out current. That's why other instruments are interfaced together and that's why laptops are so handy.
what you are driving. A GPS computer can only tell you your speed over the bottom (ground). It is your job to figure out current. That's why other instruments are interfaced together and that's why laptops are so handy.
Thanks
for all the responses. This gives me a lot of information to work with. I figure that by the time I decide on what I need/want, the technology will have changed so much that I'll be asking more questions. In the meantime, I'll be sanding teak hand and toe rails and trying to decide which route to go with those...oil, varnish, etc, etc. There's also that little scratch on the side of the boat that needs some gelcoat. Of course, when the weather improves, I wonder how much I'll be thinking about those things... NAH... nothing to wonder about there. Alan
for all the responses. This gives me a lot of information to work with. I figure that by the time I decide on what I need/want, the technology will have changed so much that I'll be asking more questions. In the meantime, I'll be sanding teak hand and toe rails and trying to decide which route to go with those...oil, varnish, etc, etc. There's also that little scratch on the side of the boat that needs some gelcoat. Of course, when the weather improves, I wonder how much I'll be thinking about those things... NAH... nothing to wonder about there. Alan
Alan, dream away
but don't bet on the technology changing too much. The BELLS AND WHISTLES will change but the technology is pretty tough to improve on. Think of vinyl records and then Cd's. THAT is a quantum leap, and that was one step after the other. Very rare. GPS is NOTHING MORE than loran with the towers orbiting in outer space. Same stuff, old tech, new location, new bell and whistles. (atomic clocks)enjoy.
but don't bet on the technology changing too much. The BELLS AND WHISTLES will change but the technology is pretty tough to improve on. Think of vinyl records and then Cd's. THAT is a quantum leap, and that was one step after the other. Very rare. GPS is NOTHING MORE than loran with the towers orbiting in outer space. Same stuff, old tech, new location, new bell and whistles. (atomic clocks)enjoy.
speed over ground vs. hull speed.....
....I don't know about the rest of you but speed through the water (hull speed) is of very little importance to me when I am using the gps to navigate. It is very important when I'm not using the gps....why? because dead reckoning requires it....but the point of dead reckoning is to try to estimate distance covered over ground. That being said... When is the last time any of us gps owners actually practiced our piloting skills or dead reckoned a position or course???? I'll be honest and tell you that other than taking an occassional fix with the handheld compass and plotting a few lines of position....never!! Speed is speed....and how fast I am making progress to my next waypoint, or the distance I've travelled, etc. is all I am normally interested in. This data is all related to speed over ground, so I rarely hook up the knotmeter. The GPS gives me so much more information and it's a no brainer to use... no calculations needed. The knotmeter has become less important to the non-racing boater because of the GPS. Oh, by the way, did they ever make a handheld Loran device?
....I don't know about the rest of you but speed through the water (hull speed) is of very little importance to me when I am using the gps to navigate. It is very important when I'm not using the gps....why? because dead reckoning requires it....but the point of dead reckoning is to try to estimate distance covered over ground. That being said... When is the last time any of us gps owners actually practiced our piloting skills or dead reckoned a position or course???? I'll be honest and tell you that other than taking an occassional fix with the handheld compass and plotting a few lines of position....never!! Speed is speed....and how fast I am making progress to my next waypoint, or the distance I've travelled, etc. is all I am normally interested in. This data is all related to speed over ground, so I rarely hook up the knotmeter. The GPS gives me so much more information and it's a no brainer to use... no calculations needed. The knotmeter has become less important to the non-racing boater because of the GPS. Oh, by the way, did they ever make a handheld Loran device?
Thanx Joe
for a sane response. It's point A to point B...that's measured on the ground. Brad on the Willy T
for a sane response. It's point A to point B...that's measured on the ground. Brad on the Willy T
New Garmin models
One improvement that will make those little screens much more readable is the introduction of color units, which are coming out this month. Improved day-readable color is the way they are all going now. Also the units vary in the amount of internal memory which determines what size area you can load into them. More bucks of course. I think for racing the 76 might be good because it doesn't have excess detail like depths, etc. You get an uncluttered picture with shore outline, nav aids and your course info. For cruising, on the otherhand, I want the water detail of a Bluechart, etc.
One improvement that will make those little screens much more readable is the introduction of color units, which are coming out this month. Improved day-readable color is the way they are all going now. Also the units vary in the amount of internal memory which determines what size area you can load into them. More bucks of course. I think for racing the 76 might be good because it doesn't have excess detail like depths, etc. You get an uncluttered picture with shore outline, nav aids and your course info. For cruising, on the otherhand, I want the water detail of a Bluechart, etc.
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