PDA

View Full Version : GPS vs. Compass


Descant
03-26-2016, 09:27 PM
There's a lot of chatter here about various GPS and whichever chip to use. As as a long time boater before GPS, I'm curious what the GPS folks use for back up. We rarely see info here about using a compass and timing runs to get from A to B in the fog. Do people compensate their compass or even use it? At night, from Wolfeboro to the Weirs, you can pretty much see the red mountain top lights related to the Laconia Airport, so there should be no reason for disorientation, but I've never seen reference to these lights or other landmarks for navigation on this site. You really don't need GPS under VFR conditions, and if you're IFR, you need a back up.
What do you use? Please don't tell me you get around using GPS or Bizer when the sun is shining. That's not the point of the question.

kawishiwi
03-26-2016, 09:46 PM
There's a lot of chatter here about various GPS and whichever chip to use. As as a long time boater before GPS, I'm curious what the GPS folks use for back up. We rarely see info here about using a compass and timing runs to get from A to B in the fog. Do people compensate their compass or even use it? At night, from Wolfeboro to the Weirs, you can pretty much see the red mountain top lights related to the Laconia Airport, so there should be no reason for disorientation, but I've never seen reference to these lights or other landmarks for navigation on this site. You really don't need GPS under VFR conditions, and if you're IFR, you need a back up.
What do you use? Please don't tell me you get around using GPS or Bizer when the sun is shining. That's not the point of the question.

Used to lead wilderness canoe trips with map & compass. Very rarely needed the compass but for those few occasions it was, fog, night, ultra complex island chains, it was irreplaceable. Now I am a huge fan of gps with a good map chip while boating but always have map & compass on board.

Slickcraft
03-27-2016, 05:11 AM
Long ago I learned to get from Welch to Glendale in the early morning fog with route on a map, compass and watch timer. Not easy to hold a course at slow speed with no visual reference and keeping look out for other boats etc. One complication is knowing how much the compass is knocked off by use of nav lights and/or wipers.

Now the compass is still one input however the GPS is the main nav aid in fog. It provides confirmation of being on track also the GPS heading read out is not affected by use of boat electrical systems.

thinkxingu
03-27-2016, 05:36 AM
I've only needed to get home once in the dark without my GPS (thought it'd be a short ride, so didn't take it...). Since we're in Hanson Cove, we just used the Bizer map and hugged the north coast after orienting ourselves with my Tissot Touch's compass.

Sent from my XT1528 using Tapatalk

jeffk
03-27-2016, 06:12 AM
I'm sure that many might disagree with me but as far as I am concerned, there is no backup to a GPS except for another GPS. I just downloaded the Navionics map to my Samsung Note and will make sure I take it with me when boating as backup as well as for mechanical distress calls. I never get in the boat without my GPS running.

Why? Because all the other methods are estimates and are subject to error, even visual navigation. I almost went into the Witches one time because I misunderstood where I was. I'm still not sure how I got mixed up up I did. It was a beautiful day and I could see everything perfectly. I did realize at the last minute that something was out of whack, slowed to a crawl and eased up to a marker. When I checked the number I realized how mixed up I was. OK, if I was really paying attention to my chart and compass I probably wouldn't have got mixed up to begin with but I didn't and I believe that most people cruising around on a sunny day are not focused on their chart and compass either. They have a sense of where they are and 99% of the time they are right. But the GPS is right whether you pay meticulous attention or not.

GPS places you exactly on a map with references to everything nearby. There can be no mistakes based on confused thinking or lack of visibility. The more you use it the easier it becomes to use the map and other features. You can make a track going out during the day and follow it back at night or save it for another night. You can even get tracks from other people or enter in waypoints.

Compass and chart are old standbys but it takes some practice to get good at it. Who really practices using compass and charts on a regular basis? If you are not very practiced, what will the result be? Even if you are accomplished, it is an approximation only. It might be fine out in the ocean but in this lake, 50 ft off can mean you are on the rocks instead on in clear water.

Frankly, it I were out on a dark night or in fog and my GPS and phone backup was not working I would be most likely to find a place to tie up and call a friend for a ride home.

tis
03-27-2016, 06:53 AM
Descant, in a dark foggy night those red mountain top lights can be out of view. The one and only night we ever got lost on the lake you could not see your hand in front of your face. It is just a miracle we made it home. We have no idea how we did or where we were until I finally spotted the end of Tuftonboro Neck by Wingate Cove. I think there were about 12 of us on the boat and we had gone through the Gov. Island Bridge and were going to come back on the other side of GIB. Just as we went under the bridge, it started to pour and the lightening and thunder started. We think we might have ended up going between all the islands but to this day we don't know. It is a miracle we never hit something but we did have somebody sitting on the front of the boat, so if a buoy came up we could see it. I have been on the lake my whole life and that was the only time we ever got lost.

Orion
03-27-2016, 07:57 AM
I'm sure that many might disagree with me but as far as I am concerned, there is no backup to a GPS except for another GPS. I just downloaded the Navionics map to my Samsung Note and will make sure I take it with me when boating as backup as well as for mechanical distress calls. I never get in the boat without my GPS running.

Why? Because all the other methods are estimates and are subject to error, even visual navigation. I almost went into the Witches one time because I misunderstood where I was. I'm still not sure how I got mixed up up I did. It was a beautiful day and I could see everything perfectly. I did realize at the last minute that something was out of whack, slowed to a crawl and eased up to a marker. When I checked the number I realized how mixed up I was. OK, if I was really paying attention to my chart and compass I probably wouldn't have got mixed up to begin with but I didn't and I believe that most people cruising around on a sunny day are not focused on their chart and compass either. They have a sense of where they are and 99% of the time they are right. But the GPS is right whether you pay meticulous attention or not.

GPS places you exactly on a map with references to everything nearby. There can be no mistakes based on confused thinking or lack of visibility. The more you use it the easier it becomes to use the map and other features. You can make a track going out during the day and follow it back at night or save it for another night. You can even get tracks from other people or enter in waypoints.

Compass and chart are old standbys but it takes some practice to get good at it. Who really practices using compass and charts on a regular basis? If you are not very practiced, what will the result be? Even if you are accomplished, it is an approximation only. It might be fine out in the ocean but in this lake, 50 ft off can mean you are on the rocks instead on in clear water.

Frankly, it I were out on a dark night or in fog and my GPS and phone backup was not working I would be most likely to find a place to tie up and call a friend for a ride home.

Jeff I pretty much agree with you on all points except I would add one thing. If the fog is really thick, it's good to have a compass only because it's almost impossible to hold a steady heading at slow speed, in fog, using just a GPS. And, I also use my depth sounder to confirm that my depth matches the depth of where I think I am on the chart. Plus when the depth starts to get shallow, it's time to stop.

Pilots always confirm readings among several instruments and rarely rely on one, especially when one doesn't look right.

Farfrumbehavin
04-03-2016, 07:58 AM
Good GPS $500, New lower unit $2500. The plotter has detail that a paper chart just doesn't have. The chart is with me at all times but is clumsy and the GPS tells you where you are on the chart at all times with just a glance. As i have become more familiar with the lake I have become more comfortable. I am in the saltwater most of the time so I have 2 units and a compass. I am upgrading my chartplotter to take advantage of the new sonar technologies, so I will be selling my Lowrance. It's a 5" HDS Chartplotter/Fish Finder combo with coastal charts from Nova Scotia to Cuba a Navionics Insight sd card that has the eastern us lakes. Lake winni is in HD and the detail is amazing. Will come with the sonar transducer. Cost me $950 I would like to get $400 for it but will accept offers.