GPS vs. Compass
05-06-2005, 07:36 PM
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GPS vs. Compass
I wish to surface mount my new GPS on my 88' Bullet, but it looks as though only either the compass or the GPS will fit. Should I even consider not having a compass and only have the GPS? Any thoughts?
05-06-2005, 07:57 PM
#3
JC Performance Engines
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Re: GPS vs. Compass
I use my gps to give me a heading, then use my compass for bearing.
To me, a compass is much easier to read, and is further ahead in my line of sight. With a good compass in the right location, you should barely have to look down. thats why so many older hp boats have the compass out on the deck.
Tough question to answer for someone else... and even though i can read charts and plot courses, its much easier w/ gps and but w/o gps, i'd probably end up going nowhere new.
To me, a compass is much easier to read, and is further ahead in my line of sight. With a good compass in the right location, you should barely have to look down. thats why so many older hp boats have the compass out on the deck.
Tough question to answer for someone else... and even though i can read charts and plot courses, its much easier w/ gps and but w/o gps, i'd probably end up going nowhere new.
05-06-2005, 08:36 PM
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Re: GPS vs. Compass
It is amazing how things change. Now we say how did we ever survive without GPS. I don't know the answer, but we did. I guess it is the same way that we survived without the internet, cell phones and cable TV.. just to name a few.
05-06-2005, 08:38 PM
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Re: GPS vs. Compass
I agree with Stormrider.
Although it does stand to mention that achieving a proper heading is MUCH easier with the GPS. . . . then, just quick glances to the compass to maintain your bearing. . . . you will be slightly off your mark - but most times easily within visual correction range ( unless in pea-soup conditions, which is where GPS really shines ). Love my GPS, but live by my compass.
Although it does stand to mention that achieving a proper heading is MUCH easier with the GPS. . . . then, just quick glances to the compass to maintain your bearing. . . . you will be slightly off your mark - but most times easily within visual correction range ( unless in pea-soup conditions, which is where GPS really shines ). Love my GPS, but live by my compass.
05-07-2005, 08:58 AM
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Re: GPS vs. Compass
I swear by GPS. If you only have one or the other, make
it GPS. Having said that, while GPS has a compass function
it only operates when you are in motion. Sitting still, GPS will
not tell you which direction your nose is pointed. So in essence, a true compass is very different than a GPS and can do things a GPS cannot. Note that some of the newest GPS
are coming with a true compass function in them though.
I get great amusement from this fact, like the time I went into the marine store and told them I specifically wanted an electronic compass (so I could mount the sensor way up in the bow where the magnetic field from my multiple speakers won't interfere with it like they do with a conventional compass). To which the guy at the store responded by telling me that their GPS have compass functions. NOT the same thing.
The last reason to have both is that you should always have a redundancy of navigation methods.
Pesky Varmint
it GPS. Having said that, while GPS has a compass function
it only operates when you are in motion. Sitting still, GPS will
not tell you which direction your nose is pointed. So in essence, a true compass is very different than a GPS and can do things a GPS cannot. Note that some of the newest GPS
are coming with a true compass function in them though.
I get great amusement from this fact, like the time I went into the marine store and told them I specifically wanted an electronic compass (so I could mount the sensor way up in the bow where the magnetic field from my multiple speakers won't interfere with it like they do with a conventional compass). To which the guy at the store responded by telling me that their GPS have compass functions. NOT the same thing.
The last reason to have both is that you should always have a redundancy of navigation methods.
Pesky Varmint
05-07-2005, 09:17 AM
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Re: GPS vs. Compass
The very first time I took the wife out past the sight of land my gps lost it's signal. It came back up... but not before I received a bruise for not having a back up compass.
05-07-2005, 09:37 AM
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Re: GPS vs. Compass
A compass is nice to have, but they are not easy to use correctly. I can plot a true course on a chart to the nearest degree, but my compass is marked at 5 degrees. Then you have to figure in the variation to magnetic north from your chart (and the year it was printed) to get the magnetic course, and the deviation of your compass install for the heading you're planning to get your compass course. I don't think many people go through these steps and without them, you could be following your compass on a course that's say, 10 degrees off what you should be following. Run that course for 20 miles and you'll be maybe 5 miles from where you expected to be. These are approximate measurements, but you get the idea.
A compass is good to have, but a GPS is much more user friendly.
A compass is good to have, but a GPS is much more user friendly.
05-07-2005, 09:40 AM
#9
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Re: GPS vs. Compass
I am going through the same type of choice. I have decided to keep the traditional compass for all of the above reasons. I will one way or another find another spot for the gps/plotter.
One thing that should be done on any boat is to set up your compass for it's surroundings.
Compass Compensation
A built-in correcting magnet system, standard on all compass models, consists of two sets of magnets fixed to two adjusting rods with slotted ends. The slots should be horizontal before starting the adjusting procedure. A small non-magnetic screwdriver is provided for this purpose. On bracket and deck models, the black plastic inserts must be removed to gain access to the slotted compensator rod ends. Before starting compensation, check the area around the compass to make sure all material of a magnetic nature is secure and in its sea-going position. Through the years, many methods and devices have been used to compensate compasses, such as gyros, azimuth circles, sextants, or a pelorus. However, we are going to show you one simple, yet effective method, using equipment that you should have on your boat, and another method using equipment you might have on your boat.
Method 1.
Step one. With the compass in its intended position, but not finally secured, select a course on your chart using two identifiable marks, buoys or landmarks that are within ten degrees (10°) of the North/South line. Try to select this course so that you can maneuver your boat "down range" of the marks selected (See example).
Step two. From a position down range of the North/South marks, and keeping the marks lined up, run the boat visually along the Northerly course selected. Turn the port/starboard compensator until the compass reads correctly.
Step three. Reversing direction, run the boat Southerly, again keeping the marks lined up. If the compass is not correct at this time, there is an alignment error. To correct, rotate the compass itself to remove one half of this error. Repeat Steps 1 and 2 and then recheck this Step 3.
Step four. Simply repeat the procedures of Steps 1, 2 and 3, except this time, using and East/West course and the fore/aft compensator, although at this time any alignment error should have been eliminated.
Step five. Upon completing the procedure, secure the compass in its final position.
Method 2. (Requires the use of GPS or Loran)
Step one. While at sea, with the compass in its intended position, but not finally secured, obtain the Loran/GPS bearing to a visual buoy or landmark that is within 10o of a North/South line.
Step two. Position your boat along that line and steer your boat directly at that mark. Turn the port/starboard compensator until the compass heading matches the Loran/GPS bearing.
Step three. Check the Southerly course by steering away from the mark, to a bearing 180° from Step 2. The compass heading should be bearing from or bearing to +180 degrees. If any error is present, it is an alignment error. Rotate the compass itself to correct for one half of this error. Repeat Steps 1 & 2 and then recheck this Step 3.
Step four. Simply repeat the procedures of Steps 1, 2 and 3 for the East/West course, using the fore/aft compensator, although, at this time, any alignment error should have been eliminated, and no alignment correction is required.
Step five. Upon completing the procedure, secure the compass in its final position.
Note: When performing this method, always use the bearing "To or From" mode on the Loran/GPS. Do not use the Heading Information because it is inaccurate in real time.
Image3.gif (5320 bytes)
To assure accuracy on all headings, check for deviation every thirty degrees and record any deviation on a deviation card. We recommend checking at the start of each boating season for changes in deviation.
If you feel that the deviation on your boat is of an unusual nature, the services of a professional compass adjuster will be a wise investment.
One thing that should be done on any boat is to set up your compass for it's surroundings.
Compass Compensation
A built-in correcting magnet system, standard on all compass models, consists of two sets of magnets fixed to two adjusting rods with slotted ends. The slots should be horizontal before starting the adjusting procedure. A small non-magnetic screwdriver is provided for this purpose. On bracket and deck models, the black plastic inserts must be removed to gain access to the slotted compensator rod ends. Before starting compensation, check the area around the compass to make sure all material of a magnetic nature is secure and in its sea-going position. Through the years, many methods and devices have been used to compensate compasses, such as gyros, azimuth circles, sextants, or a pelorus. However, we are going to show you one simple, yet effective method, using equipment that you should have on your boat, and another method using equipment you might have on your boat.
Method 1.
Step one. With the compass in its intended position, but not finally secured, select a course on your chart using two identifiable marks, buoys or landmarks that are within ten degrees (10°) of the North/South line. Try to select this course so that you can maneuver your boat "down range" of the marks selected (See example).
Step two. From a position down range of the North/South marks, and keeping the marks lined up, run the boat visually along the Northerly course selected. Turn the port/starboard compensator until the compass reads correctly.
Step three. Reversing direction, run the boat Southerly, again keeping the marks lined up. If the compass is not correct at this time, there is an alignment error. To correct, rotate the compass itself to remove one half of this error. Repeat Steps 1 and 2 and then recheck this Step 3.
Step four. Simply repeat the procedures of Steps 1, 2 and 3, except this time, using and East/West course and the fore/aft compensator, although at this time any alignment error should have been eliminated.
Step five. Upon completing the procedure, secure the compass in its final position.
Method 2. (Requires the use of GPS or Loran)
Step one. While at sea, with the compass in its intended position, but not finally secured, obtain the Loran/GPS bearing to a visual buoy or landmark that is within 10o of a North/South line.
Step two. Position your boat along that line and steer your boat directly at that mark. Turn the port/starboard compensator until the compass heading matches the Loran/GPS bearing.
Step three. Check the Southerly course by steering away from the mark, to a bearing 180° from Step 2. The compass heading should be bearing from or bearing to +180 degrees. If any error is present, it is an alignment error. Rotate the compass itself to correct for one half of this error. Repeat Steps 1 & 2 and then recheck this Step 3.
Step four. Simply repeat the procedures of Steps 1, 2 and 3 for the East/West course, using the fore/aft compensator, although, at this time, any alignment error should have been eliminated, and no alignment correction is required.
Step five. Upon completing the procedure, secure the compass in its final position.
Note: When performing this method, always use the bearing "To or From" mode on the Loran/GPS. Do not use the Heading Information because it is inaccurate in real time.
Image3.gif (5320 bytes)
To assure accuracy on all headings, check for deviation every thirty degrees and record any deviation on a deviation card. We recommend checking at the start of each boating season for changes in deviation.
If you feel that the deviation on your boat is of an unusual nature, the services of a professional compass adjuster will be a wise investment.
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I have Steps & Bubbles!
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