Compass vs. GPS

[Beefer]

I have both a compass and a GPS on board. Before GPS, I seemed to live by the compass, but I can't remember the last time I looked at it from a navigational aid stand-point.

My useless trivia question is; if you have GPS, do you still use your compass for its intended use?

 

[Drowned Rat]

Re: Compass vs. GPS

A compass is a must have for backup navigation, but it has little use now. A GPS gives you your corrected "Course Made Good" which is what you want anyway. If you're steering by compass, you must correct for set and drift for precision navigation, and I doubt there is a single person on this board who can do that. The GPS does it for you, so why bother.

I'm sure many will disagree, but to those who would argue that the magnetic compass is a failsafe piece of equipment, I say it has many more pitfalls than does a GPS.

 

[carlh]

Re: Compass vs. GPS

Should your GPS fail a compass is good backup but only if you know your current position. How many people take the time to record their position at regular intervals?

 

[5150abf]

Re: Compass vs. GPS

I fish a river so a compass would do me no good at all.

Kinda hard to get lost on a river, you go this way or that way.

 

[Frank Acampora]

Re: Compass vs. GPS

My compass looks pretty on the dash and is handy sometimes, but for keeping me out of trouble, the GPS is the way to go. However, Just like analog gauges on an auto, it is quicker to read the compass card than to interpret the digital read-out on the screen. Or to change screens to a compass card. --just look down to see direction traveled for rough course corrections.

 

[ziggy]

Re: Compass vs. GPS

you must correct for set and drift for precision navigation, and I doubt there is a single person on this board who can do that.

i can't. but if ya take a usps class, they will teach you how. not bad to know i wouldn't think considering a gps needs power. a compass don't, only education.

i use a gps and have a compass onboard.

that said, i have no use for either stuck in the cornfield of nebraska. the bodies of water just aren't that big. though i do use the charts of the lake to get a general idea of water depth... since i don't have sonar...

 

[Ned L]

Re: Compass vs. GPS

Correct for set & drift?? That's easy, you've got a copy of "Eldridge" for me to use? ---- I certainly am no expert with a GPS (far from it), but how can it correct for set & drift? A GPS would have to have the current data available to it in order to correct for it. Considering a GPS 'looks' at where you are , and where you want to end up, with no current data available, I believe it would give you only a direct course with no corrections.
Even with a GPS right next to me I still steer by compass all the time, the course is much straighter.

 

[KC4YIN]

Re: Compass vs. GPS

When I bought the boat I show here, it came with both compass and gps mounted on the console. I also carry an ETREX PORTABLE GPS, which I already had, for back up in case of total electrical failure.

 

[dingbat]

Re: Compass vs. GPS

Considering a GPS 'looks' at where you are , and where you want to end up, with no current data available, I believe it would give you only a direct course with no corrections.
Even with a GPS right next to me I still steer by compass all the time, the course is much straighter.

A GPS updates its position readings 1 second. A GPS knows exactly where you are at any given moment. At that point, set and drift becomes part of the course line correction that is also done in 1 second intervals.

 

[2ndtry]

Re: Compass vs. GPS

--- I certainly am no expert with a GPS (far from it), but how can it correct for set & drift?

I also am not an expert, but it you don't really have to be for A to B navigation. It continuously monitors your progress, if you drift (or steer off course) it gives you a new heading. You do still have to drive the boat!

EDIT: Dingbat got if first

 

[Robbabob]

Re: Compass vs. GPS

I fish a river so a compass would do me no good at all.

Kinda hard to get lost on a river, you go this way or that way.

We boat on a river too. The compass mounted on the dash came with the boat; it looks great! I use it to confirm/correct which direction I think I'm headed.

5150abf has it right... it's this way or that way.

When we grow up ~2-foot-itis kinda thing~ it would be nice to have the sonar and river nav gps for night travels. Pretty much just have to watch for the channel markers since there's "usually" enough contrast between the water and banks.

Happy boating!

 

[Mike Robinson]

Re: Compass vs. GPS

Years ago I learned how to compensate for set and drift plotting on a chart. One needs accurate information about the direction and speed of the current which is often not available.

My boat cruises at 22 knots and most currents around here are less than 3 knots (Coastal British Columbia). At this ratio, set and drift are insignificant unless crossing a very large body of water.

How many here have set their GPS to display courses in magnetic? I have, it helps determine how much deviation my compass has.

 

[Ned L]

Re: Compass vs. GPS

AH! Yes, I wasn't thinking about the constant updating aspect. True, with that taken into account it doesn't need any current information. It doesn't really correct for set & drift as a separate entity, those are automatically factored in (with everything else) when it updates your position every second. - Should have thought it through more.-
So, ... With that in mind I suppose there is no way to pull a heading off a GPS that is corrected for set & drift.

 

[Drowned Rat]

Re: Compass vs. GPS

My boat cruises at 22 knots and most currents around here are less than 3 knots (Coastal British Columbia). At this ratio, set and drift are insignificant unless crossing a very large body of water.

What about the wind?

 

[Drowned Rat]

Re: Compass vs. GPS

.

 

[bruceb58]

Re: Compass vs. GPS

How many here have set their GPS to display courses in magnetic? I have, it helps determine how much deviation my compass has.

I believe by default they all are.

 

[ajgraz]

Re: Compass vs. GPS

I have a compass just in case the FF/GPS goes kaput on an extremely overcast day and I need to know which way is East to get back to shore.

Not that my little 15'er has ever actually been out of view of land

EDIT: since the above scenario has never actually happened to me, I voted "have both, never used compass"

 

[DianneB]

Re: Compass vs. GPS

I boat on a very large and complex lake where the water can be 90 feet deep 10 feet from shore and 2" deep in the middle of a wide open area so the GPS and good e-charts are mandatory if you want to keep your bottom end but not be confined to the few published routes!

A compass and charts are a legal requirement but running this lake on Dead Reckoning by map and compass is the stuff of nightmares.

 

[howlnmad]

Re: Compass vs. GPS

GPS??? Give me a sexton, a compasss, dividers and a chart and I shall sail the world over !

Just kidding , my aqua sports are on rivers. If I get to a locke, I went the wrong way to get home.

Bill

ps: I do have a compass. My hula dancing girl is glued to the top of the dome.

 

[26aftcab454]

Re: Compass vs. GPS

I fish a river so a compass would do me no good at all.

Kinda hard to get lost on a river, you go this way or that way.

unless it is dark/storming and you pass up your take out point.

I've boating on an 8 mile long x 2mile wide lake for 20 years but still break out the GPS on dark nights just to make sure-there are several coves.