Route Tracking For River Navigation

[kirklange]

Hi all,

 

I currently use a Magellan Meridian Platinum. Recently, I have begun to explore northern saskatchewan rivers with my kayak. I typically track the entire route with my GPS as I paddle a river for the first time.

 

My question is:

Is there any software or GPS system that will enable me to first record a track of a river, second re-load that track for future navigation of said river, and third, compute ETA along the track/route given my particular position and paddeling speed.

 

My current GPS seems to record tracks and route them just fine for future use; however, it can only compute an ETA in a linear fashion (as the crow flies so-to-speak).

 

If anyone has a GPS that can do this or knows of a version number I should be running or even recommend a different GPS unit with this functionality, it would be greatly appreciated.

 

Thanks!

[+Alan2]

How many track points make up a typical mile? If you increase the amount of points, then the "as the crow flies" issue will be pretty much a non-issue.

 

I'm not familiar with Magellan. But on my Vista, I can store up to 10,000 track points before I start writing over them. I could then dump the points on a laptop and start over. Let's say I kayak 8 hours (I'm not a kayaker so you'll have to do the adjustment yourself. At an average of 5 miles an hour that's 40 miles. My Vista allows me to either select the recording interval my distance or time. Let's say I set it up by distance. So in 40 miles I can get a track point every 21 feet or 7 meters. Shouldn't that resolve your concern since each section pretty much smoothes out overall so you aren't really navigating as a straight line?

 

Also, the "problem" may not be a problem anyway. The GPS I believe is taking your "Velocity Made Good" (VMG)speed not the actual speed to determine either your ETA to the next waypoint in the route or final ETA. VMG computes the speed to the next waypoint based on the angle of attack. Your actual speed might be 5MPH (or it's kilometer equivalent for your area), but unless your paddling is directly to the waypoint, the VMG speed will be less. I believe it's that VMG speed that is used in the calculation so your ETA should be pretty accurate even though you're not traveling in a straight line.

 

edit: clarity and spelling

Edited December 17, 2003 by Alan2

[+PDOP's]

My question is:

Is there any software or GPS system that will enable me to first record a track of a river, second re-load that track for future navigation of said river, and third, compute ETA along the track/route given my particular position and paddeling speed.

 

My current GPS seems to record tracks and route them just fine for future use; however, it can only compute an ETA in a linear fashion (as the crow flies so-to-speak).

 

Most GPSr's will allow the upload/download of data including routes and tracks. The only exception I know of is the Geko 101 which has no interface port. There are also numerous programs for your PC that will allow you to transfer this data to and from your GPSr.

 

Garmins will show the ETA to each route point and to the end of the route on their Active Route Page. I don't know of any GPSr that will do the same with a track.

 

You may have better luck posting your questions on the GPS Newsgroup.

[gm100guy]

My question is:

Is there any software or GPS system that will enable me to first record a track of a river, second re-load that track for future navigation of said river, and third, compute ETA along the track/route given my particular position and paddeling speed.

 

I take it you are in Canada if the rivers you name are here.

 

The software you could try would by a topographic map package like Softmap you can then get the gps option that would let you lay down a track or route on the map and then upload those to your gps.

 

You would also be able to download the track from the day and lay it on the map to see where you have been.And save it to re upload at a later date.

 

 

I think this is the answer to your question.

 

try this link for more map options in Canada

[Vlad]

i think you are correct in how your gps is determining eta - that is on an as the crow flies basis. that said the number of track points used by your gps to store a track would be the critical value - the greater the number of track points the better an eta it is likely to give you as it will more closely represent the true path taken when originally creating the track...

[+Alan2]

I stand corrected. PDOP is correct in that the 10,000 points cannot be used to track back and get epa's until it's saved. Then you're limited to the abbreviated point count. However, that track will give you eta's if I recall correctly (I"ll have to check it later in my unit.) One solution might be to save more often so you have let's say 10 saved tracks of 150 points each or roughly one waypoint for every 130 feet of travel but that process would be pretty burdensome.

 

I still wonder though how off the ETA would be anyway?? Does anyone know for sure whether these are calculated with VMG so that the ETA will be pretty reliable even with a lower count of waypoints?

Edited December 17, 2003 by Alan2

[kirklange]

Alan,

 

are you saying the VMG calculated ETA will take into account my path along the route and is not a linear assumption?

 

you see, as I paddle, I may actually traverse 1km of river in .5km of linear direction as the river twists and turns like crazy...

 

Thus, when re-padlding a previous track along said river my ETA always seems to be waaaay off.

 

hmmmm...

[kb9nvh]

If you have topographical maps loaded then at every turn in the river you place a waypoint....then you build a route up from waypoint to waypoint.

 

Your ETE will be whatever speed your going divided by your total route mileage left to go.

 

Did I answer the right question? or were you asking something else???

 

Todd

[+parkrrrr]

Your ETE will be whatever speed your going divided by your total route mileage left to go.

You might think that, but it appears that on the Meridian, if you select "ETA" for display on the main map screen, it gives you the ETA for the next route point, and not for the end of the route. I haven't been using my Meridian very long, though, so it's quite possible that there's another field that shows the ETA for the total route (as "Total Distance" does for mileage.) Oddly enough, I just checked the manual and it doesn't even mention "Total Distance," so maybe that came with a firmware upgrade.

 

(Edit: just noticed that you said "ETE" rather than "ETA." The difference is that ETE is a duration, and ETA is a clock time. The same caveat applies, however: the manual for the Meridian says that both are the estimated time for the active leg of the route.)

Edited December 17, 2003 by parkrrrr

[+PDOP's]

...are you saying the VMG calculated ETA will take into account my path along the route and is not a linear assumption?

 

you see, as I paddle, I may actually traverse 1km of river in .5km of linear direction as the river twists and turns like crazy...

 

kirklange

 

I've never used the ETA, ETE or VMG on my GPSr very much but your questions have got me wondering too

 

The following is from Dale DePriest's online manual for Garmins

 

"Other interesting data includes ETE, estimated time enroute, and ETA, estimated time of arrival. To compute these numbers you need to use an estimate of your speed. Garmin calculates the speed vector that is actually in the direction of the destination and calls this VMG, velocity made good, based on your current speed and direction. The handhelds covered in this manual (except for the etrex and emap, see below) all use the current VMG as the effective speed for calculating ETE and ETA. VMG is a pretty good indicator of your effective speed if you are moving at a steady speed over the ground and are approximately headed in the right direction. It is also accurate if you are in a sailboat tacking toward an up-wind mark by zig-zagging back and forth. Similarly a car traveling on city streets may have to do the same thing but the destination may not be directly "up wind". Either take the VMG on the closest tack in the direction of the destination or better yet average the two to arrive at the most probable ETA.

 

The etrex and emap also use VMG to estimate ETE and ETA, however the way it is measured differs on these units. Instead of a current VMG they use a previous sustained velocity to calculate VMG. Changes in speed or direction will not change the VMG until the magnitude and direction settles down to a new constant speed. In addition no change in calculation of VMG is done when you are stopped. Under these condition the old VMG will be used to update the ETE and ETA values. Unfortunately there is no way to display the VMG that the unit is currently using, however you can force it to compute a new one. To do this temporarily stop navigation from the local menu and then start it again. "

 

I think the best approach for what you want to do is to used one of your saved tracks to create a route with the maximum number of waypoints allowed by your GPSr. When doing this manually you could insure that all major turns or bends in the river are marked so your route doesn't cut across a bend in the river

 

On Garmins you could then use the Active Route Page or the Highway page to show the ETA or ETE.

 

One more interesting point about using a saved track instead of a route (again from Dale's manual)

 

"In other respects the emap, 76, and etrex backtrack navigation behaves like a route navigation that is obtained on the other units. An exception is that time and distance calculations are always made to the final destination since there is no intermediate waypoints."

 

So you would not be able to see ETA's for the waypoints along your route just the destination. His manual also states that only 50 significant points are used in a saved track for naviagtion which is the same as the maximum number of waypoints in a route.

[EagleI]

The Meridian series uses VMG, or Velocity Made Good, to calcualte the ETA. In other words, if you are going 60 mph at an angle to the direct line of sight and your VMG is 30 mph, it will estimate your ETA as 2 hours out from a 60 mile distant destination.

 

parkrrr - I knew that math didn't sound right, but I knew what I thought I meant when I said it. Edited above is what I think I really meant.

Edited December 17, 2003 by EagleI

[+parkrrrr]

The Meridian series uses VMG, or Velocity Made Good, to calcualte the ETA. In other words, if you are going 60 mph at a 45 degree angle to the direct line of sight and you are 60 miles from your destination, your ETA will be 2 hours out.

The cosine of 45° is approximately .707, so you'll really be about an hour and 25 minutes out (VMG is your actual velocity times the cosine of the difference in angle between your heading and the bearing to the waypoint.)

 

The larger problem here seems to be that the ETA and ETE on the Meridian are for the current leg of the route, and not for the total route. If someone knows a way to fix that, I, for one, would be very interested in hearing about it.

[+Sparky-Watts]

Sounds like you've gotten plenty of good advice here. I was going to suggest more route points, but don't know the Magellan's that well.

 

Another alternative, in order to get your eta's to match, is to paddle faster!

[kirklange]

The larger problem here seems to be that the ETA and ETE on the Meridian are for the current leg of the route, and not for the total route. If someone knows a way to fix that, I, for one, would be very interested in hearing about it.

THIS HITS THE NAIL ON THE HEAD...

 

I could care less what my ETA is to the next bend in the river... I care more when it is I'll be getting to my next camp/next beaching site.

 

My main use for this function is to allow me to better estimate my "time to spare" whilst exploring the river banks and to also allow me to figure out if I should keep paddling or make camp given questionable weather... If I could know that I was only say 45 min from a previous, sheltered spot I used last time then I might continue paddling....

 

I want to know on the last day of a trip when it is I can expect to be getting to my unloading site, such that I can arrange for pick-up etc....

 

Oh yeah - Thanks for all the great info and replies!!!!!!!!!!!!!

Edited December 18, 2003 by kirklange

[+PDOP's]

I hope you find a solution before spring. I don't imagine you can do much exploring of northern Saskatchewan rivers with your kayak this time of year.

[+Alan2]

My main use for this function is to allow me to better estimate my "time to spare" whilst exploring the river banks and to also allow me to figure out if I should keep paddling or make camp given questionable weather... If I could know that I was only say 45 min from a previous, sheltered spot I used last time then I might continue paddling....

 

I want to know on the last day of a trip when it is I can expect to be getting to my unloading site, such that I can arrange for pick-up etc....

 

I don't know about the Magellan, but the Vista keeps running values for average speed while moving, moving time, stopped time, overal average speed, etc. Average speed while moving could help you in this calculation. If you know how far you have to travel from either the route remaining or take a reading to your final waypoint, you can divide by average moving speed and get a rough idea of how long it would take.

 

Another way of doing it with the 10,000 points is to save the original trip to your computer. Original track points record the time at each point. So if you take a printout of all the track points, you can use that data to more accurately figure the time left. You could also use this log to calculate time to any point in the river you are travelling to in advance of the trip.

 

One final suggestion. I hope you're taking a waterproof bag for the GPS. While somewhat waterproof, I doubt it's survival if it takes a good dunking.