Map Miles

Joined
Sep 18, 2011
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105
Location
SE MI
What is the best (most accurately) method to draw/measure off miles on a river on a topo? I have a map measuring wheel but feel it is not accurate. It seems to slip around on my waterproof topo maps. Just curious what method everyone uses.

Thanks Kaine
 
Joined
Sep 18, 2011
Messages
105
Location
SE MI
Re: Map Miles

For anybody else that might be interested; I posted the same question on another forum. There were a few suggestions. Use a string that you bend to the shape of the river. Another suggested using a twist tie in a similar manner as the string (This seems to be the easiest to me). Another suggested using Google earth. Google Earth would be the most accurate but unfortunately I am not that familiar with all the abilities of it.
 
Joined
Aug 5, 2011
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Western NY between Buffalo and Rochester
Re: Map Miles

Good ideas....thanks for sharing!
I have discovered I like to study the google satellite images before going on a trip. It gives me a good sense of the proximity of major landmarks. Things always look so different from the ground.
Old orienteering guides always tell you to study your map and know it well...I guess Google Earth would be the modern way of doing part of that.
Good luck on your trip planning!
Scott
 
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Sep 18, 2011
Messages
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SE MI
Re: Map Miles

Thanks ScottB. I check out all forms of map I can find. Along with google satellite images, I also check out bing birds eye images.
 
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Jul 25, 2012
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I've never thought about the business of measuring the mileage along rivers. It also could be any wiggley feature, maybe a trail, but if I wanted to make it as accurate as possible I'd get one of those jewelry chains, very fine. Lay that down and push it to the shape of the river. Also on each end I'd thread through a fine wire and twist it like a barber pole. That ought to help with finding the ends and keeping the chain from becoming knotted. When my daughters were little every now and again they'd get a knot in some pendant chain and it was a booger to un-knot it.
Rob
 
Joined
Dec 7, 2011
Messages
425
Location
Maryland, USA
Seeker,
Your tick mark method works well. The electronic methods are all pt to pt and it is next to impossible to measure a river with lots of bends and turns etc. I have used the tick method for years when i had a twisty turny river to navigate with pretty good accuracy. I have been a professional navigator (ships) and sometimes the simplest and easiest things work the best
regards,
Dave
 
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Map Miles vs GPS Miles

Map Miles vs GPS Miles

In the field I use a small piece of string or dental floss and bend/hold it along the twists and turns an inch or two at a time as I position it incrementally along the course. At home I have an 18” length of old jewelry chain which seems somewhat more accurate.

(Moldy – when I pulled it out to measure it had a knot in it. Still does dammit)

I have noticed is that both my crude string or chain measurements and the mileages listed in paddling guidebooks consistently come up a little short of rivermiles recorded by friends bearing GPS on trips.

My string or chain mileage estimates of big lake or bay paddling are almost certainly even less accurate. And even less useful in planning; I can’t predict how much coast hugging, windage ferrys or zig zagging the route will entail until after I’ve actually paddled it. Five mile trips have become 12+ in challenging conditions.

On river trips the GPS distance is frequently longer than the guidebook listing, even taking into account some eddy turns and upstream play. There is one very short section of my local homeriver that is significantly guidebook overestimated.

The exactitude of any listed mileage is suspect. On a Lumber River trip a few years back we had mileages from two guidebooks and a couple of park publications and none of them matched, not even comparing the ones from the Park.

I expect that guidebook listings have improved with the advent of GPS, at least in later editions of those still in publication. But I rarely replace my guidebooks and don’t use a GPS.

Question for paddlers who use a GPS. What is your experience in guidebook miles vs real miles? Or in predictive miles; is that type of planning is possible with a GPS?
 
Joined
Nov 23, 2012
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693
Location
Western Adirondacks
Question for paddlers who use a GPS. What is your experience in guidebook miles vs real miles? Or in predictive miles; is that type of planning is possible with a GPS?
Accurate measurements via Google Earth do it for me.

I don't use a GPS for recreational paddling, as in general I find those things distracting and unnecessary to more traditional and enjoyable observational navigation. But I do use a GPS for marathon canoe racing. Mostly to be sure I maintain my speed goals, and in the bigger races also to know how far in distance/time to the next major loaded waypoint.

I've paddled the big Yukon RIver races several times. Using a GPS there is critical to competing. Existing topo maps are horribly inaccurate due to the age of the existing maps and the vastly changing character of the river. The long published distance from Whitehorse to Dawson City is 460 miles, based on the old paddle wheelers best estimate in the main river channel. GPS mileage as measured by several GPS units over 4 years on the Yukon races consistently comes out to 426 miles to Dawson. The significant difference is partially understandable and expected since paddlers will naturally take shortcuts out of the main channel, but I'm not sure you can account for 34 miles of difference that way.

Google Earth, on the other hand, shows accurately registered images of the river that are only a couple of years old in most places (as opposed to the decades old topo maps). When paddling/racing on the Yukon it is extremely important to know where you are, to set up for which side of the upcoming gravel bar to be on, or which side of the river for an upcoming turn and best current. The river is so wide and current so strong, you can't simply wander from shore to shore without a detailed route plan.

I use the Google Earth ruler/path function to set waypoints and accurately measure the exact track I want to take. GE map measured distance to Dawson is 419 miles, vs actual GPS measurement of 426 miles. Not bad, a difference factor of 1.016. I attribute the slight difference to wandering in our paddle course and carving turns. Going even further to the finish of the Yukon 1000 mile race, that same factor holds true to compare actual GPS with the ever slightly shorter GE map measurement.

So I use this to my advantage. I carefully plot the route on GE and have GE create a database of the waypoints coordinates so made, in this case 446 waypoints to get me around river bends and islands from Whitehorse to Dawson (738 points to Dalton Bridge). The spreadsheet calculates distance and names waypoints by their distance in tenths of a mile from Whitehorse, and also includes in the waypoint name the upcoming turn direction, and desired river left/right information. This route and waypoint list is loaded into the GPS. I also print and waterproof a map from GE with the same route and labeled waypoints. This makes it very easy to glance at the GPS display with the upcoming waypoint showing direction and distance to next, and the name correlates to the printed map waypoint if I should need to refer to a larger picture. The GPS odometer also corresponds to the waypoint name upon arrival. In practice one GPS is displaying direction and course, another is displaying the map.

The spreadsheet also predicts and adjusts, based on our actual location and SPOT transmissions, the expected arrival times at various upcoming points of interest (including the finish) for my pit crew. It is quite accurate and very cool.
 
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Feb 1, 2013
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I use my GPS software on my computer (Basecamp) to measure distances before a trip. You can zoom in or out for whatever scale makes for accurate measurement. My main purpose is to try to plan out campsites, etc. Measuring this way is very accurate, and corresponds closely to the measurements my GPS makes over the course of the day. With the variety of computer mapping systems out there, I haven't used the old string method for years.

I have found a lot of the old maps I use have exaggerated distances on portages. Three miles often becomes three kilometers, 1000 yards is frequently 600 meters. These distances are usually messed up on very difficult ports...Perhaps the original predictors were going by time, and some of those ports take a lot more time. On the other hand, many of our ports up here were originally measured by trappers or surveyors, and are listed in "chains". The distances listed in chains usually accurately reflect what my gps says.
 
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what they taught me in the military was you can take a strip of paper and a pencil then draw a mark on the edge of the strip and the start point of the map the mark off with dots following the river with the paper. it kinda marks up your map but when the strip has all the waypoint marks use the scale on the map to estimate the distance. or use a compass and protractor and do the same think but that requires alittle decimal math...
 
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