G'day, I recently went on an excellent one day navigation course and exercise, which finished with us checking our ability to navigate by aiming to paddle to a particular fixed point and then comparing our dead reckoning against a GPS. The group of about 14 paddled independent courses, but were all out by about 10%. i.e 900 metres after a 9km paddle. I'ld be interested to know how accurate other people can be and any advice they might have? All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
PeterO said: > The group of about 14 paddled independent courses, but were > all out by about 10%. i.e 900 metres after a 9km paddle. > > I'ld be interested to know how accurate other people can be > and any advice they might have? Peter, That's not bad for ded reckoning, but 900 meters is a little more than 1/2 mile. That could cause you to miss an island if visibility was limited. That's probably why most people call ded reckoning, dead reckoning. (It's actually an abbreviation of "deduced reckoning". Steve Holtzman Southern CA. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Steve wrote: >but 900 meters is a little more than 1/2 mile. G'Day Steve, Quick response - Thanks! Missing small landing sites/islands was our concern. The instructor described just such a situation as you referred to. A situation where at the end of a long days paddling in Tasmania, with only one possible landing spot, a very small and somewhat hidden beach. It was the first time most of us had tried ded reckoning. Things I think could improve my accuracy are: - 1. Select bearings which were likely to be clearly defined i.e large objects such as points, light houses, water towers, with high contrast in the line of sight. A point covered in trees against a backdrop of a coast covered in trees was one of the poor selections I made, it was almost invisible in fact. 2. Take a hard surface on which to put the map for plotting bearings, if possible do most of the plotting in advance at home 3. Use a portland square rather than protractor and setsquare. 4. If using laminated maps take a fine water proof pen (and some alcohol as an erasor). 5. The theory looked easy, putting it into practice on the water was hard. 6. Work out in advance which direction to paddle if bearings aren't quite right. These all seem to be minor embellishments except for 1. I'ld appreciate thoughts on better technique - particularly accurate reading of a compass on the water. All the best, Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
PeterO said: > It was the first time most of us had tried ded reckoning. > Things I think could improve my accuracy are: - > > 1. Select bearings which were likely to be clearly defined > i.e large objects such as points, light houses, water towers, > with high contrast in the line of sight. A point covered in > trees against a backdrop of a coast covered in trees was one > of the poor selections I made, it was almost invisible in fact. > 2. Take a hard surface on which to put the map for plotting > bearings, if possible do most of the plotting in advance at > home 3. Use a portland square rather than protractor and setsquare. > 4. If using laminated maps take a fine water proof pen (and > some alcohol as an erasor). > 5. The theory looked easy, putting it into practice on the > water was hard. > 6. Work out in advance which direction to paddle if bearings > aren't quite right. Peter, All excellent ideas. I personally prefer to use a map and compass only while on the water and do most of the route planning and back-up planning before I get in the boat. It's real hard to use a divider or compass in a moving boat. I usually just use my thumb for distance measurements and a calibrated eyeball together with a finger or hand to get bearings. I learned the hard way to always carry a GPS. Last year I organized a 14 mile roundtrip coastal paddle. We launched and landed at our 1/2 way point in beautiful typical Southern California weather. After having brunch at a beachside restaurant, we went back to the boats to find fog so thick that you couldn't see more than 20-30 feet in front of you, and fairly large surf. After launching and searching for 45 minutes for one missing paddler (compass washed off of the boat, broke a paddle returning to the beach--spare was carried by his son already on the water), until the CG notified us by radio, that the paddler was on the beach--at least he used his head and phoned them), we had a stressful paddle back to our launch site. It was disconcerting to measure distance off of the shore by the sound of breaking waves, not being able to see more than one or two other paddlers, and not being able to identify the beach we launched from because the shoreline was invisible. As a result, I almost always have the GPS with me now, I just don't use it for the majority of my navigation and never as my sole navigational aid. BTW, a friend showed me that he just writes all of his waypoints, bearings, etc on the front deck of his glass boat with a permanent marker. Acetone seems to take it off fairly easily. Even though my boat is not new, I'm not sure if I'm ready to try this yet. All the best, Steve Holtzman *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Steve wrote, >SNIPIt's real hard to use a divider or compass in a moving >boat. SNIP I learned the hard way to always carry a GPS. G'Day Steve and Paddlewise, I'm not that handy in a boat:~) The hard surface was for working with maps on the beach. But I agree much better to plot at home if possible. What I did find diffiult in the boat was getting an accurate deck compass reading while checking bearings. I wound up trying to average readings over about a minute, but can't help thinking there might be a better way or perhaps one could change the compass fluid for something more viscous - maybe that would work? I've only ever taken one paddler through thick fog - a relatively easy paddle across a 3km channel called Murray Pass, between Deal and Erith islands in Bass Strait - taking a large group through fog sounds tough in the extreme. All the best and thanks, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter wrote: > What I > did find difficult in the boat was getting an accurate deck compass reading > while checking bearings. I wound up trying to average readings over about a > minute, but can't help thinking there might be a better way or perhaps one > could change the compass fluid for something more viscous - maybe that would > work? For this reason, it's handy to carry a small hiker's compass in your PFD. Bearings are easy to take without having to rotate the kayak. Bob V *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Thanks Peter & Steve for excellent suggestions and insights. Steve wrote: > BTW, a friend showed me that he just writes all of his waypoints, bearings, > etc on the front deck of his glass boat with a permanent marker. Acetone > seems to take it off fairly easily. Even though my boat is not new, I'm not > sure if I'm ready to try this yet. The acetone does remove permanent ink, but it would be more conservative to use a grease pencil (china marker) for the same purpose. I haven't had much trouble with information rubbing off. Another alternative, when there is a lot of data to be stored over multiple days, would be to use a permanent marker to write the information on a plastic sheet, such as a page protector. This can be secured under bungies or even taped to the deck. Bob V *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 5 Jun 2004 at 13:51, Bob Volin wrote: > The acetone does remove permanent ink, but it would be more > conservative to use a grease pencil (china marker) for the same > purpose. I agree - acetone is nasty stuff and I don't use it at all. Even for epoxy work, I prefer to make do with vinegar than use acetone. > multiple days, would be to use a permanent marker to write the > information on a plastic sheet, such as a page protector. This can be > secured under bungies or even taped to the deck. Divers use plastic boards that can be written on under water. That is also a possibility. One of these days, I'll find out what the plastic is and find a cheap source. Ditto the type of marker. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Michael Daly wrote: > > Divers use plastic boards that can be written on under water. That > is also a possibility. One of these days, I'll find out what the > plastic is and find a cheap source. Ditto the type of marker. > > Mike The plastic is usually PVC and the marker is usually a pencil. Some divers cut a PVC pipe (large diameter) in half lengthwise and bungie it to their arm to use as a slate. michael *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Paddlewisers, The beauty of dead reckoning is not knowing exactly where you are. Then someone in the group panics, turns on the GPS, and ruins it all. Duane Strosaker Southern California www.rollordrown.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 5 Jun 2004 at 19:48, PeterO wrote: > 3. Use a portland square Peter, I've never heard of this. Could you point us to what one looks like? I tried a google search but came up with nothing but references to a place in Portland (OR, ME and Bristol UK) once I filtered out the hotel. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> > 3. Use a portland square > > Peter, > > I've never heard of this. Could you point us to what one looks like? I presume it is a square protractor. Have a look at this: http://www.whom.co.uk/html/protract.htm We don't own a round protractor, but have a couple of these. Allan Singleton *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Michael wrote: - > 3. Use a portland square > Peter, > I've never heard of this. Could you point us to what one looks like? Allan wrote >I presume it is a square protractor. >Have a look at this: > http://www.whom.co.uk/html/protract.htm G'Day, Allan, what a useful web page, excellent description of how to use a square protractor, thanks! Here is a web page that describes a few different protractors including a Portland Square and Douglas protractor. I think the Portland Square and Douglas protractors are very similar & maybe the same. http://ca.binnacle.com/online/dept.asp?dept_id=18065 I can see what Michael means about searching the web under the name Portland square - It seems to be a very popular part of London. All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Of practical use is the following 2001 article in Seakayaker: http://www.seakayakermag.com/2001/01April/Nav1.htm ... on the off chance you didn't know it was there and very useful! Tom >G'Day, > >Allan, what a useful web page, excellent description of how to use a square >protractor, thanks! > >Here is a web page that describes a few different protractors including a >Portland Square and Douglas protractor. I think the Portland Square and >Douglas protractors are very similar & maybe the same. > > http://ca.binnacle.com/online/dept.asp?dept_id=18065 > >I can see what Michael means about searching the web under the name Portland >square - It seems to be a very popular part of London. > >All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Since visibility may be poor due to fog or just your closeness to shore, #6 is extremely valuable. I've used for hiking off trail in relatively thick woods, and several times in a kayak as well, including thick fog. Its very frustrating to arrive at a "line" (shoreline, reef line, trail, etc) and not know which way to turn. In some visibility and/or terrain situations, if you are off by as little as a few hundred meters you'll be forced to make a guess with only a 50:50 chance of getting it right. A few hundred meters could turn into miles. The key to working it out in advance is deliberately plotting a course to one side of your destination, such that with reasonably expected errors you are guaranteed to miss in that direction ONLY. This all depends on having some "line" that you know you have reached, so that you can turn in the proper direction. If it's a shoreline or some other "line" that can't be missed it's a piece of cake. Obviously, it's also important that the consequences of a miss to one side are tolerable. If you're shooting for a very small island in the middle of a very big ocean after a very long leg, this may not be the case. I have read of using time, estimated paddling speed, current, and wind effect to make a stopping point (Standard dedrec waypoint). Then paddling increasing diameter circles until dryland is spotted. That may work well in an environment with little wind or current, but I'd probably turn on my GPS anyway if I couldn't spot land by reaching the waypoint. I'm sure there are some salty island hoppers on the list that have actually worked this scenario out for real without benefit of GPS. Any island I have paddled to in low visibility was too close and too big to miss entirely. Steve Brown -----Original Message----- G'Day Steve, ........ 1. Select bearings which were likely to be clearly defined i.e large objects such as points, light houses, water towers, with high contrast in the line of sight. A point covered in trees against a backdrop of a coast covered in trees was one of the poor selections I made, it was almost invisible in fact. 2. Take a hard surface on which to put the map for plotting bearings, if possible do most of the plotting in advance at home 3. Use a portland square rather than protractor and setsquare. 4. If using laminated maps take a fine water proof pen (and some alcohol as an erasor). 5. The theory looked easy, putting it into practice on the water was hard. 6. Work out in advance which direction to paddle if bearings aren't quite right. ...... All the best, Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Steve Brown said: > I have read of using time, estimated paddling speed, current, > and wind effect to make a stopping point (Standard dedrec > waypoint). Then paddling increasing diameter circles until > dryland is spotted. That may work well in an environment with > little wind or current, but I'd probably turn on my GPS > anyway if I couldn't spot land by reaching the waypoint. > I'm sure there are some salty island hoppers on the list that > have actually worked this scenario out for real without > benefit of GPS. Any island I have paddled to in low > visibility was too close and too big to miss entirely. Steve, I agree with Duane Strosaker that it is more "fun" to use just a map and compass. But like you, I would turn on my gps if I had any real doubts as to where I was. Steve Holtzman *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> Paddlewisers, > > The beauty of dead reckoning is not knowing exactly where you are. Then > someone in the group panics, turns on the GPS, and ruins it all. I wouldn't put it better :-)... Back to Peter's question: I've been in the situation just like you described - looking for a hidden landing (narrow, about 20 meters, river mouth) in the darkness, in the place where I had never been before. GPS batteies died when I was close (and knew that was close), and if it wasn't for weak glimpse of the last fading light of the sky (after sunset) in calmer waters of river mouth, I wouldn't have found it. There is no way to arrive precisely at such spots using dead reckoning - either GPS is needed, or may be a very powerful ship searchlight :-) *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 6/5/2004 3:06:22 AM Pacific Daylight Time, sh_at_actglobal.net writes: > BTW, a friend showed me that he just writes all of his waypoints, bearings, > etc on the front deck of his glass boat with a permanent marker. Acetone > seems to take it off fairly easily. Even though my boat is not new, I'm not > sure if I'm ready to try this yet. > A grease pencil works really well and comes off with minor elbow grease and water. Rob G *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 6/5/2004 2:50:55 AM Pacific Daylight Time, rebyl_kayak_at_iprimus.com.au writes: > . Select bearings which were likely to be clearly defined i.e large objects > such as points, light houses, water towers, with high contrast in the line > of sight. A point covered in trees against a backdrop of a coast covered in > trees was one of the poor selections I made, it was almost invisible in > fact. > 2. Take a hard surface on which to put the map for plotting bearings, if > possible do most of the plotting in advance at home > 3. Use a portland square rather than protractor and setsquare. > 4. If using laminated maps take a fine water proof pen (and some alcohol as > an erasor). > 5. The theory looked easy, putting it into practice on the water was hard. > 6. Work out in advance which direction to paddle if bearings aren't quite > right. > Another suggestion would be to time a mile at the trip start and see approximately how long it takes with your group, in the conditions, etc., to go that mile. Tick off on your chart with a grease pencil the mile increments along intended course, every time the estimated time length expires. Rob G Whose laid up this weekend and living vicariously through you people. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
>From: "Steve Holtzman" <sh_at_actglobal.net> >Subject: RE: [Paddlewise] Dead Reckoning Accuracy > > >That's not bad for ded reckoning, but 900 meters is a little more than 1/2 >mile. That could cause you to miss an island if visibility was limited. > >That's probably why most people call ded reckoning, dead reckoning. (It's >actually an abbreviation of "deduced reckoning". > > The best explanation origin of the term I've found is at: http://www.straightdope.com/mailbag/mdeadreckoning.html which notes that the term "dead reckoning" appears to have a much longer history with the earliest reference cited by the Oxford Dictionary being from 1613 whereas the use of "ded" for deduced seems to have started in the 20th century. The term "dead" may relate to its uses in phrases such as "dead right" meaning absolute rather than relative or to the use of objects that are "dead in the water" when estimating speeds for dead reckoning. It could also come from a comparison of dead reckoning to other forms of navigation where frequent 'live' updates are made based on bearings to landmarks, celestial sights, etc. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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