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  1. #31
    Join Date
    Jun 2011
    Location
    Berkshire, UK
    Posts
    2,734

    Default Re: Get your position right...

    Quote Originally Posted by prv View Post
    If he's transmitting his position, where does remembering numbers come in? Why not just read them off the screen - are the plotter and VHF at opposite ends of the boat? And having written down his lat and long, why's he trying to find the corresponding position on the chart in order to transmit... the lat and long he already has? No - he heard the lat and long of a distressed boat read out, once, on the radio, and now he's scrambling to figure out where those half-remembered numbers point to in real-world terms. I regularly have the exact same problem.


    Post #17 doesn't confirm that he's trying to find his own lat and long, it's a description of how it's difficult to turn a lat and long into a position on (one model of) plotter. He has to keep clicking on spots to see if the lat and long it presents for that location is the one he copied for the distressed boat. None of that makes any sense if it was his own position he wanted. Even if his plotter didn't have a direct read-out, he'd at least only have to click the cursor once, on his own little boat symbol, not keep hunting and pecking around the ocean until he finds where the one in trouble is.

    Pete
    Surely every plotter has the ability to be given a waypoint by lat/long and show it on the plot? And would not every user know how to do that?

    Mike.

  2. #32
    Join Date
    Oct 2008
    Posts
    172

    Default Re: Get your position right...

    Some years ago, I heard a 'mayday' call from a motorboat in the Solent, correctly giving Lat and Long. The coastguard response included a suggestion that 'just off Yarmouth pier' would have been sufficient.
    The rescue was carried out by the water taxi.

  3. #33
    Join Date
    Oct 2006
    Location
    Bradwell and Leigh-on-Sea
    Posts
    14,491

    Default Re: Get your position right...

    Quote Originally Posted by mjcoon View Post
    Surely every plotter has the ability to be given a waypoint by lat/long and show it on the plot? And would not every user know how to do that?

    Mike.
    I have a Yeoman. Finding a position is easy and to instantly show range and bearing. Some electronics I see on friends boats seems to very complicated and they just use the screen to show their own position. Perhaps they don't use it often enough or for other purposes like route planning. Even a DSC manual is a small book.
    Not all who wander are lost

  4. #34
    Join Date
    Nov 2001
    Location
    scotland
    Posts
    3,432

    Default Re: Get your position right...

    Quote Originally Posted by mjcoon View Post
    And I think that would be connected with the fact that adjacent "positions" have no relation to each other, so it is impossible to see if one position is near another or far away, unlike lat/long or OSGB.

    Mike.
    True itís both a plus and a minus
    Itís a little bit like the stopped clock only being correct twice a day as opposed to a slow clock being almost right most of the time

  5. #35
    Join Date
    Feb 2007
    Location
    Essex
    Posts
    22,902

    Default Re: Get your position right...

    Quote Originally Posted by prv View Post
    If he's transmitting his position, where does remembering numbers come in? Why not just read them off the screen - are the plotter and VHF at opposite ends of the boat? And having written down his lat and long, why's he trying to find the corresponding position on the chart in order to transmit... the lat and long he already has? No - he heard the lat and long of a distressed boat read out, once, on the radio, and now he's scrambling to figure out where those half-remembered numbers point to in real-world terms. I regularly have the exact same problem.


    Post #17 doesn't confirm that he's trying to find his own lat and long, it's a description of how it's difficult to turn a lat and long into a position on (one model of) plotter. He has to keep clicking on spots to see if the lat and long it presents for that location is the one he copied for the distressed boat. None of that makes any sense if it was his own position he wanted. Even if his plotter didn't have a direct read-out, he'd at least only have to click the cursor once, on his own little boat symbol, not keep hunting and pecking around the ocean until he finds where the one in trouble is.

    Pete
    I'm sorry if it wasn't clear but you are right, it was the difficulty of locating another boat's position on the screen that I was referring to. My own position is patently obvious, as well a being available on a repeater. All I can say about those who think that finding another boat's position from a broadcast lat and long is easy is that they can't have tried it while on passage. A chart helps, but even on a chart it takes time to plot an exact position.
    Far away is near at hand in images of elsewhere

  6. #36
    Join Date
    May 2007
    Location
    Cambridge, UK
    Posts
    6,171

    Default Re: Get your position right...

    Quote Originally Posted by biscuit View Post
    I have been in the position of asking for CG assistance in very squally (20-30kt) conditions and and having to give them updated positions. Despite having a mike and plotter at the helm, the wind was bad enough to affect the command mike, so I had to go below to the chart table radio and plotter be audible, leaving a rather inexperienced crew to handle the boat.
    No big problem, but it would have been more difficult if single handed.
    Is "What 3 Words" the way of the future? I'm surprised that there seems to have been little discussion of this innovative system on these forums.
    Not at sea, I don't think, for several reasons:

    1) Almost all vessels have direct access to lat/long. Anyone with access to WhatThreeWords certainly does!
    2) DSC transmits lat/long automatically.
    3) WhatThreeWords is biased towards English speakers (I may be wrong about that, but if I am, it means that an English speaker receiving a French whatThreeWords might not recognize and be able to spell all the words, and vice-versa). The sea is international...
    4) I think WhatThreeWords depends on an internet connection, but I'm not sure of that. It obviously requires access to a lookup table to supply the words. I make it that there are about 100,000,000,000,000 possible combinations required to cover the whole Earth (back of the envelope calculation, but reasonable!) - that requires a vocabulary of around 29,000,000 words to cover the world.
    5) Does WhatThreeWords cover the whole surface of the Earth? Considerations such as the above suggest that it doesn't and can't.

    I think WhatThreeWords is a great idea for terrestrial use, where most people haven't the faintest idea of their position in any absolute coordinate system. But at sea, we do (or should) have a pretty good idea of our position in absolute Lat/Long coordinates. Precision isn't that important - degrees and minutes ought to get a SAR resource close enough in most circumstances; and even getting it down to 10 second accuracy will get SAR to within a couple of hundred yards. Until the advent of GPS, most of us didn't know our position more accurately than that!

    I agree entirely that a position given with reference to well-known named locations is useful as well, though, for all the reasons already given - while it isn't a problem for me to give lat./long, I confess that I'm not always particularly awarof my lat/long when out for a day, and a position given with respect to the things I'm eye-ball navigating by would be better to allow me to know whether I'm in a position to give assistance or not.

  7. #37
    Join Date
    Jun 2011
    Location
    Berkshire, UK
    Posts
    2,734

    Default Re: Get your position right...

    Quote Originally Posted by scottie View Post
    True it’s both a plus and a minus
    It’s a little bit like the stopped clock only being correct twice a day as opposed to a slow clock being almost right most of the time
    Oh dear, are we about to stray into relativity?

    Mike.

  8. #38
    Join Date
    Jun 2011
    Location
    Berkshire, UK
    Posts
    2,734

    Default Re: Get your position right...

    Quote Originally Posted by johnalison View Post
    I'm sorry if it wasn't clear but you are right, it was the difficulty of locating another boat's position on the screen that I was referring to. My own position is patently obvious, as well a being available on a repeater. All I can say about those who think that finding another boat's position from a broadcast lat and long is easy is that they can't have tried it while on passage. A chart helps, but even on a chart it takes time to plot an exact position.
    Perhaps a non-marine example is relevant. I have a smartphone and tablet. The phone has a new and sensitive GPS and can be held against an airliner window to tell me how far we have got (to pass the time...). But the tablet is better for showing a map. So I wrote a small program that displays lat/long as one of those QR 2-D bar-codes on the phone screen. The tablet bar-code reading app recognises it as a location and calls up a map program. So I don't have to copy the numbers across myself.

    Admittedly QR codes are no help on a voice channel, but digital would be so much more reliable for this purpose, and maybe even W3W locations could be spelled out if they are ambiguous, and easier to put in short-term memory. (I suppose ideally the words are never puns!)

    Mike.

  9. #39
    Join Date
    Jun 2011
    Location
    Berkshire, UK
    Posts
    2,734

    Default Re: Get your position right...

    Quote Originally Posted by AntarcticPilot View Post
    I make it that there are about 100,000,000,000,000 possible combinations required to cover the whole Earth (back of the envelope calculation, but reasonable!) - that requires a vocabulary of around 29,000,000 words to cover the world.
    According to my home-made calculator:
    100000000000000 ^ (1/3)=46415.8883361278
    (where "^ (1/3)" means cube-root)

    So five thousand words should be enough, three at a time.

    Mike.

  10. #40
    Join Date
    Sep 2001
    Location
    Me - Zumerzet Boat - Wareham
    Posts
    12,307

    Default Re: Get your position right...

    Quote Originally Posted by johnalison View Post
    I'm sorry if it wasn't clear but you are right, it was the difficulty of locating another boat's position on the screen that I was referring to. My own position is patently obvious, as well a being available on a repeater. All I can say about those who think that finding another boat's position from a broadcast lat and long is easy is that they can't have tried it while on passage. A chart helps, but even on a chart it takes time to plot an exact position.
    It's me that should apologise for misinterpreting your post!
    A tip for finding the other boats relative position (having written down the Lat/Long) Put an arbitrary WP into your CP, then edit the Lat/Long to the written down one, then GoTo that WP will give you Range and Bearing.
    MontyMariner.co.uk
    Facilitated by AWESEM WP Agency

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