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Thread: Hand Held GPS - Combination Land and Marine

  1. #76

    Re: Hand Held GPS - Combination Land and Marine

    billfisher, I have been through the car cigarette lighter thing, a marine one should be heaps better, but I finished up cutting open the lead & creating a direct connection to 12v using bullet conectors ( with separate fuse), this works really well. Easy to plug up or remove & the lighter connection still works in the car.

    Just how I did it.

    Muzz

  2. #77
    marlinqld
    Guest

    Re: Hand Held GPS - Combination Land and Marine

    Thats how i run my 72 on my boat billfisher, never a problem.

    Mike

  3. #78

    Re: Hand Held GPS - Combination Land and Marine

    Onerabbit,

    Thats good thinking, but I think I might go the lighter plug way as it will be handy for other accessories like fluorescent lights and air pumps.

    I have a dedicated full sized GPS for the boat as well. Perhaps someone could help me with a problem I have with it. It wouldn't power up the other day. I checked the fuse and found it was burnt out. Now when I replace the fuse it will burn out immediately.


  4. #79

    Re: Hand Held GPS - Combination Land and Marine

    G'day Billfisher,

    Check the condition of your wiring and check the terminals on the cable at the unit for corrosion.

    There is a short somewhere to be causing this.

    The cigarette lighter plug is easy to wire in ... just ask Blackened where you connect your positive and negative wires to ... is positive the centre post of the outer casing?

    Mostly, you would wire them into your switch panel, which usually have fuses in them anyway.

    Be wary of damage to the units with the wrong sized fuse. Your GPS would run on (say) 3 amp fuse, while your spotlight would need 15 - 20 amp and heavier wiring... and alternatively, the GPS connected to a 15 amp fuse may cause damage and void warranty.


    Sat Nav,

    You are completely right in what you have said ... but if you had taken the time to realise that not everyone understands the basic principles of surveying, and backtracked and explained more simply, you would have had a captive audience instead of an arguement...


    Muzz and others,

    If I may explain on SatNav's behalf...

    Everything on the earths surface has an exact coordinate.

    You would see surveyors setting out roads and also putting in the square, white block pegs in a new housing estate. These block pegs have a nail in them, and are accurate to milimetres.
    The Surveyor gets his information to set these block pegs out, by setting his machine (called a theodolite) up off a PSM (Permanent Survey Mark) where the exact coordinate is known within milimetres.
    You may have seen these in the top of kerb and gutter - they are a round brass disc with survey written on them.

    Anyway - the point is, surveying like this will give you accuracy to milimetres. (which is why surveyors generally dont use GPS)(apart from the cost)

    So, lets say that your front block peg at your house has the exact surveyed coordinates of 20.00.000 degrees South / 150.00.000 degrees East.
    If you were to take your hand held GPS and sit it on the peg, the coordinate it showed would not be exactly 20 by 150 ... it would be more like 20.00.050 degrees by 150.00.050 (approximately 15 - 18 metres out either way).

    Now, this is where SatNav is trying to explain accuracy by GPS. In other words, GPS is not accurate, when trying to establish exact coordinates on the ground that would be accurate like a surveyor is.

    BUT

    If you were to mark the waypoint with your GPS on this block peg, walk up the street and then come back ... the GPS would put you back over the peg (or within a few feet).

    SO...

    The GPS is relatively accurate by being able to return to one of its own waypoints (like Muzz Says)

    But the GPS is relatively inaccurate in establishing an exact known point on the earths surface - like SatNav says.... typically any point shown on your gps will be within 15 or so metres of the real life, exact surveyed coordinate numbers.

    And also, if you were to take a Garmin, a Lowrance and a Raymarine GPS, they would all return you to the block peg, but all would be showing slightly different coordinates at the one spot.

    Has this been of any value to anyone?

    Cheers

    Pete

  5. #80

    Re: Hand Held GPS - Combination Land and Marine

    Thanks Grand Marlin. Yes the plug looks a bit corroded so I might just replace it and give it another try.

    As to the hand held unit I was thinking about your comments concerning wiring a fuse and I just discovered it has fuse within the lighter plug. In that case a bigger fuse in the female connector will be OK and will cover the other accessories. I don't have any spare switches on the panel so I might just wire it direct to the busboard. Perhaps a switch is not neccessary as other connectors such sounder, radio etc are always 'live' too.

  6. #81

    Re: Hand Held GPS - Combination Land and Marine

    Thanks for that GM,

    You have explained the differences really well.

    I did understand that SatNav was trying to make a point as he kept refering to "accuracy". I certainly have NO experience in that field !
    The only reason I answered in the first place was that I was impressed with the G72.
    Hope it can rest at that.

    Cheers all ,

    Muzz

  7. #82

    Re: Hand Held GPS - Combination Land and Marine

    1. Grandmarlin, this has nothing to do with the principles of surveying (not one thing) but the very simple principle of GPS SPS accuracy and these two should never ever be confused

    2. This misconception that surveyors do not use GPS due to the lack of millimetre accuracy is rather misguided and the differences betwen real property/cadastral surveying and GPS orientated surveys I doubt we have the time to go into, not in a way that many might understand anyway. Lets just say it is far more easier and currently more legal and quicker to pull out a tape over 20 metres than set up a GPS base line for a week. Pleae do not confuse these two and this comment is completely off track.

    3. Might I also add Grandmarlin that every point on the earth has many#exact coordintes, and why coordinates by themselves actually mean nothing to anybody.

    4. Since PSM's were mentioned, anybody ever wonder where the coordinates for these were actually derived from and using what means?

    5. The entire coordinate backbone (ARGN/AFN) in this country is derived and controlled by GPS means and is real world accurate to the sub milliletre mark and what more is actually controlled on a week by week basis due to this country moving about 0.2mm (that is one fifth of one millimetre per day) per day.

    6. Real property / cadastral surveying is something that should not be confused with GPS methods

    7. The whole point of GPS Standard Positioning Accuracy continues to be entirely missed as there is simply no recreational anything that has any hope of ever returning to the same point (known or unknown) to "within a few feet". Why are some of you people totally misguided ????????????? A GPS will not put you back over the peg to within a few feet NOT POSSIBLE, not right now, some people do need to understand this point. #

    # #

  8. #83

    Re: Hand Held GPS - Combination Land and Marine

    Billfisher,

  9. #84

    Re: Hand Held GPS - Combination Land and Marine

    G'day
    Aah pete. It's been a long time since I've done a cig lighter installation, and by memory the positive is the centre post.
    Dave
    PRECISION DETAILING
    For all your MARINE DETAILING needs
    www.precisiondetailing.com.au
    0421802691

  10. #85

    Re: Hand Held GPS - Combination Land and Marine

    Onerabbit,

    Yes I just found a fuse in the plug and I altered my post accordingly.

  11. #86

    Re: Hand Held GPS - Combination Land and Marine

    Yes Dave, centre post is positive.

    I assume most cars these days are negatively earthed, and will therefore make the gps units compatible from car to boat.

    SatNav

    Boys, enjoy your fishing...

    Cheers

    Pete

  12. #87

    Re: Hand Held GPS - Combination Land and Marine

    1. As I have mentioned and will obviously continue to mention the whole point and cabability of GPS accuracy has been entirely missed. TOTALLY. Why does this not surprise me?


  13. #88

    Re: Hand Held GPS - Combination Land and Marine

    I think accuracy is relative to what you do,I would be surprised if anyone actualy anchors up on a mark if there's no fish showing with the hope of something showing up,I generaly cover a lot of ground around any marks I have before deciding to anchor up/drift through or move on so to me within 50 metres is "accurate".

  14. #89
    Bundy_Burp
    Guest

    Re: Hand Held GPS - Combination Land and Marine

    I have sat and read this entire thread and considering the original question have not seen a more off topic load of cr@p in my life .
    Guys who really gives a rats @rse about the inaccuracy of GPS I mean many of us use the system almost daily and as far as I know we are all getting back to port safely and not ending up in some foriegn country .
    I have used many GPS units over the years the early 1s where shocking the new 1s are fantastic and yes they do get me to within casting distance of my favorite fishing spots every time not sometimes EVERY time .
    So people answer the question or go fishing and maybe this forum might run a lot smoother.
    I have had my say and now will say NO more on the matter.

  15. #90

    Re: Hand Held GPS - Combination Land and Marine

    1. At least you can cast more than a few feet then?

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