+BasicPoke Posted February 7, 2015 Share Posted February 7, 2015 Hello bm-ers, When on a benchmark/geocache run, what are some tips to maximize your number of finds? For example how long do you look for a marker before giving up? How do you document each bm find quickly before moving on to the next? Is it important how fast you gun your engine and drive to the next one? Thanks Ron Quote Link to comment
2oldfarts (the rockhounders) Posted February 8, 2015 Share Posted February 8, 2015 Hello bm-ers, When on a benchmark/geocache run, what are some tips to maximize your number of finds? For example how long do you look for a marker before giving up? How do you document each bm find quickly before moving on to the next? Is it important how fast you gun your engine and drive to the next one? Thanks Ron To maximize your finds you need to read the descriptions carefully and follow their directions. How long to look for a benchmark? I have been known to spend almost a full year searching for a single mark that I was sure was still there and Yes I did find it. Talk about satisfaction! It is not about the number of finds or the time spent, it is about deciphering the description and making the find. John Quote Link to comment
2oldfarts (the rockhounders) Posted February 8, 2015 Share Posted February 8, 2015 Here is an example of determination - GQ0012 - It took 2 years to finally recover this one and it had not been recovered since it was monumented in 1934. The area where it was placed had not been changed. The only change in the description was the highway had been leveled with fill to eliminate the rolling hills so the 18" culvert was not visible. I knew the mark would still be in a rock outcrop, it was just a matter of finding the correct outcrop. Man, there are a lot of outcrops in that area! John Quote Link to comment
+dprovan Posted February 8, 2015 Share Posted February 8, 2015 My advice is to maximize your fun instead of maximizing the number of finds. Fun has a lot of value. Finds have none. How long do I look for a mark? Generally I look until I don't think I'm going to find it, although sometimes I will cut a search short because of higher priorities. I normally snap a picture of the mark and a picture or two of its environment. In rare cases, such as when the mark was hard to find or I'm the first to log a find at GC.com, I might take a measurement. I take as long as I need, since what's important at that time is accurately documenting this mark, not worrying about any other marks I might want to look for. I always walk when I'm looking for benchmarks. Quote Link to comment
+BenchmarkHunter Posted February 9, 2015 Share Posted February 9, 2015 I will search for a marker until I'm satisfied that I'm not going to find it. A rule of thumb is that I'll probably call off a search after 15 minutes, or so, though I've searched for longer, at times, and, sometimes, I'll look for another nearby benchmark that I can use as a reference point for my GPS. Remember, too, that "scaled" benchmark locations are only accurate to about 50 or 100 feet in each direction, which means that you could be searching for a 4-inch disk within an area of 1/4 acre. A keen eye is invaluable, and experience becomes key. Even when there are photos from a previous benchmark hunter, those could be, for instance, almost 10 years old, and lots could have happened in a decade: construction, painting/repainting of the benchmark, natural disasters, etc. I do my homework before looking for markers, so I have some idea of whether there have been significant changes to the locale, or whether there are possible typos in the datasheet. I try to go after benchmarks that I believe I have a chance to find, i.e. not marks that were on buildings demolished decades ago. I plan my route, but also allow for changes as I go along. And I've learned, in New York City, to take the time to look for other survey marks near any benchmark that I've found. Benchmark hunting does produce "statistics," but the real fun, for me, has been learning about New York City's history and geography, as well as getting outdoors and enjoying the fresh air. It's also exciting to find a benchmark that hasn't been logged for decades. Quote Link to comment
+dprovan Posted February 9, 2015 Share Posted February 9, 2015 Remember, too, that "scaled" benchmark locations are only accurate to about 50 or 100 feet in each direction, which means that you could be searching for a 4-inch disk within an area of 1/4 acre. Is the 50-100' number some kind of standard? I'm not sure I've ever found scaled coordinates to be within 100'. My expectation is within a tenth of a mile, but I keep my mind open to a even larger offset. Maybe that's just California. Quote Link to comment
+BenchmarkHunter Posted February 9, 2015 Share Posted February 9, 2015 Is the 50-100' number some kind of standard? I'm not sure I've ever found scaled coordinates to be within 100'. My expectation is within a tenth of a mile, but I keep my mind open to a even larger offset. Maybe that's just California. Not necessarily a standard, just an observation. Scaled marks' coordinates are produced from someone reading a map. If the mark is accurate to 1 second of longitude or latitude, those are roughly 100 feet. Maybe I've been influenced by benchmarks in New York City, many of which are set on buildings, which may make scaling more accurate. And, truth told, I have searched for, and found, marks further away than 100 feet from the datasheet's coordinates. Quote Link to comment
foxtrot_xray Posted February 9, 2015 Share Posted February 9, 2015 Remember, too, that "scaled" benchmark locations are only accurate to about 50 or 100 feet in each direction, which means that you could be searching for a 4-inch disk within an area of 1/4 acre. Is the 50-100' number some kind of standard? I'm not sure I've ever found scaled coordinates to be within 100'. My expectation is within a tenth of a mile, but I keep my mind open to a even larger offset. Maybe that's just California. Like BM Hunter said, it's a rough guesstimate. It can vary, too in the longitude scale (E<->W) depending on your latitude. It also is assuming that the folks doing the scaling chose the right position on the map. There have been some I've found where the scaler(?) picked the wrong road, or the wrong bridge, etc. Quote Link to comment
Bill93 Posted February 9, 2015 Share Posted February 9, 2015 I believe when they scaled the marks they TRUNCATED to the nearest second of latitude and longitude. That means that in addition to whatever accuracy they had in reading the map and recognizing features in the description, there is another 0 to 70 or 75 feet of uncertainty to the west and 0 to 100 feet to the north from the stated coordinates. That rule of thumb has held for me in the majority of cases. Sometimes, however, the recognition of features from the description wasn't so good and it has been off further than expected. For instance taking the westernmost street on a small town map as West Street, when there had been an addition to the town since the original naming of the street. Also, watch out for highway movement. I know of one mark (apparently destroyed) that was placed on Highway 30 as it existed in the 1930's. The coordinates were scaled in the 1960's when Highway 30 was most of a mile south of the original location, and today Highway 30 is another mile south of that. Quote Link to comment
+dprovan Posted February 9, 2015 Share Posted February 9, 2015 Thanks for the discussion. It sounds like it's really quite different out here in California. I guess it's a combination of less detailed maps along with fewer and less permanent landmarks to pin the location down with. When I'm trying to work out a mark's location based on the description, I have a hard enough time even though I can use the space views and street views to try to work out where the culvert or "big tree" are or were, so I'm not surprised someone using nothing but a paper map couldn't get closer than 500'. Quote Link to comment
+LSUFan Posted February 10, 2015 Share Posted February 10, 2015 The scaled marks around here usually have +/- 6 seconds on the datasheets, which is over 600 feet. I assumed all scaled datasheets had this disclaimer. I have found scaled marks a lot more than 6 seconds off. CQ0059.The horizontal coordinates were scaled from a topographic map and have CQ0059.an estimated accuracy of +/- 6 seconds. Quote Link to comment
Bill93 Posted February 10, 2015 Share Posted February 10, 2015 Yes, they have the disclaimer. My experience is that they are more often within or just outside the 0-100 ft N and W range providing that there was enough information in the old description that was still correctly identifiable on the map when the coordinates were scaled. Up to 6 seconds seems to occur more when there was no identifiable feature nearby still on the map, and the distances were "7.6 miles from the RR station" like another recent thread quoted. Quote Link to comment
2oldfarts (the rockhounders) Posted February 11, 2015 Share Posted February 11, 2015 One of the first things we figured out about scaled marks was to disregard the given coordinates and follow the description. We also learned that by following the description like "7.6 miles from the RR station" would get us close to where we should be and if we just opened our eyes we might see a block of concrete, or some pink flagging tape or even a witness post. A topo map has a great many marks indicated on it and and they are usually pretty accurate where they show the mark located. You may get lucky and the mark you are after will be one of those marked on the map. Be sure to get coordinates for where you find the mark. We usually set the GPSr right next to the mark and get a good clear picture of the mark and GPSr so when we log it we can post fresh coordinates and a picture so the next person who wishes to find/use the mark will know if we found the correct mark and have good coordinates to use to get to the mark. Again, it is not about how many you find, it is about being accurate in your find log, so others can quickly locate that mark and know up-front that you actually found and logged the correct mark. John Quote Link to comment
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