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Check that link out. It has info on how to connect a GPS to the Yamaha Fuel Management gauge. If thats what you are trying to do.
Andy
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Mines connected this way and I've still got MPG. It's just more accurate when it gets GPS data than when based on data from the Speedometer, which uses data based on the pitot-tube pickup on the lower unit either way. With mine there's no way to get GPS Speed, only MPG.
OK, this is getting confusing. All I want is an accurate speed reading from the Yamaha speedo, without looking at the GPS screen or cleaning the little hole every time I pass by some type of vegetation. I don't want to lose the mpg readout on my Yamaha fuel management gauge, even though that information is pretty depressing. Maybe I'll just clean out my pitot tube, enjoy the bliss of ignorance, and get on with my life.
Command Link gauges will accept a speed signal from either the pitot or from an external GPS. Either way, you still get an MPG reading. Of course, speed and MPG calculated using the GPS signal will be more accurate. To change the source of the speed signal, GPS or pitot, you have to fiddle with the dip switches on the back of the Yamaha gauges. It's in the manual.
I've heard that it is possible to display the Command Link output in a more user-friendly fashion on an external display, like a Raymarine C-80. I'm not 100% sure about this, because I've also heard that Command Link is not NMEA 2000 compliant.
I'm currently having an electronics installation done, and I've asked the installer to do all of the above. He's sort of scratching his head. Any guidance would be appreciated.
My statements above are only intended for the style of gauges that I have, 2002 vintage. There's on displayed on a table in the link above.
The fuel flow meter gets it's speed signal from either the speedometer or a GPS, so it will display MPG based on either the pitot pickup or GPS.
The speedometer only accepts input from the pitot tube.
When I purchased my boat I had both Speed & MPG based on the pitot tube input. With simple wiring changes, as described in the link above, I now have Speed based on pitot tube input and MPG based on GPS input.
If your running (a) Command Link gauge(s?) I can't say from personal experience whether any of this applies or not.
C/L gauges will take a NMEA 0183 input, and display speed, depth and temp from it, and MPG and all teh other features work fine. Mine does, when it was hooked to a Garmin 2006c, and now a 3010c. Additionally, on a past boat with the round f/m gauge, i was able to mpg and reading fine with the GPS hooked to it.
Edit: I did have to turn on some additional NMEA sentences on the garmin 2006 for it to ouput the correct stuff.
wait a minute. I am following all this, but have one question...How could MPG be more accurate using GPS? I am not sure about that statement.
For example, GPS knows your speed over the ground, but doesnt have any provision for moving water. If you were holding a steady position into a 3 kt. current, GPS would tell you you were burning fuel but not moving at all on the surface of the planet. Thats true, but its not accurate. you are doing 3 kts. an hour through the water.
Its like people saying they get their heading from the GPS. No, they dont. Not without a compass input. GPS knows which direction on the face of the earth the antenna is moving, but has no clue as to whether its moving that way bow first or drifting sideways. or even stern first.
Try backing down in a straignt line for a while, long enough to plot your movements on your GPS. It Thinks yer boats going forward, now, dont it?
Also, back to speed...GPS speed includes the water current effects without compensation. If you are doing 30 mph downcurrent in a 3 mph current, GPS tells you you are doing 33. And you are, over the ground. When you turn around and run home it will tell you you are doing 27 mph, and you are...but if you dont mentally factor in the current, you might think yer mileage just went to hell. Your pitot or paddlewheel is a basic sensor and measures your input parameter. GPS is a calculation. Theres a difference.
wait a minute. I am following all this, but have one question...How could MPG be more accurate using GPS? I am not sure about that statement.
For example, GPS knows your speed over the ground, but doesnt have any provision for moving water. If you were holding a steady position into a 3 kt. current, GPS would tell you you were burning fuel but not moving at all on the surface of the planet. Thats true, but its not accurate. you are doing 3 kts. an hour through the water.
Its like people saying they get their heading from the GPS. No, they dont. Not without a compass input. GPS knows which direction on the face of the earth the antenna is moving, but has no clue as to whether its moving that way bow first or drifting sideways. or even stern first.
Try backing down in a straignt line for a while, long enough to plot your movements on your GPS. It Thinks yer boats going forward, now, dont it?
Also, back to speed...GPS speed includes the water current effects without compensation. If you are doing 30 mph downcurrent in a 3 mph current, GPS tells you you are doing 33. And you are, over the ground. When you turn around and run home it will tell you you are doing 27 mph, and you are...but if you dont mentally factor in the current, you might think yer mileage just went to hell. Your pitot or paddlewheel is a basic sensor and measures your input parameter. GPS is a calculation. Theres a difference.
It would have to be more accurate. The GPS will show you true speed over land; as you stated the pitot tube or wheel may not--it will just tell you current speed. You only need one more variable, fuel consumption, to tell the MPG. Injector pulses or a wheel in the fuel line will tell you that. So once you get the best measurements of each, you have the most accurate picture of your fuel mileage.
I didn't understand what you were talking about with the traveling backwards thing.
thanks for the reply Joe. I probably could be clearer, and will try. Also, I want to understand this myself, so dont take this as a blathering pronouncement. that sometimes happens here.
Ok..Use my example. the boat is holding a position in a 3 kt. current on the nose. The GPS says the boat aint moving. And its right. As far as the sats are concerned, the boat is absolutely still. BUT the engine is turning, what, maybe 1200 rpms? Burning fuel? But its not moving.
Wont the GPS speed input information tell you that you are burning fuel at a recognizable rate, but you aint going anywhere?
As you said, GPS shows you true speed over ground/land whatever. But thats not what you want to know when you are concerned with miles per gallon of fuel consumed. Ok...lets say you idle there for an hour holding position. You have burned an hours worth of fuel, whats that, 4 gallons per engine ( just an example). ? and you havent moved a foot forward.
GPS will tell you that you have burned four gallons of gas and didnt move. Thats all true....
but its not the info you were looking for. Your Miles per gallon is Zero, and its wrong.
Does that make sense?
Ok...one more way to look at it.
You sit still for 12 hours in the mouth of the Columbia river. You didnt move an inch on the earth. You burnt up all yer fuel. GPS says you didnt move from the spot where you started.
Ok...you didnt move, but you burnt 48 gallons of fuel. SO using calculations...you got zero miles per gallon. didnt move any miles, burnt all them gallons.
you dont wanna junk that boat based on your GPS info on how lousy your mileage is.
wait a minute. I am following all this, but have one question...How could MPG be more accurate using GPS? I am not sure about that statement.
For example, GPS knows your speed over the ground, but doesnt have any provision for moving water. If you were holding a steady position into a 3 kt. current, GPS would tell you you were burning fuel but not moving at all on the surface of the planet. Thats true, but its not accurate. you are doing 3 kts. an hour through the water.
Its like people saying they get their heading from the GPS. No, they dont. Not without a compass input. GPS knows which direction on the face of the earth the antenna is moving, but has no clue as to whether its moving that way bow first or drifting sideways. or even stern first.
Try backing down in a straignt line for a while, long enough to plot your movements on your GPS. It Thinks yer boats going forward, now, dont it?
Also, back to speed...GPS speed includes the water current effects without compensation. If you are doing 30 mph downcurrent in a 3 mph current, GPS tells you you are doing 33. And you are, over the ground. When you turn around and run home it will tell you you are doing 27 mph, and you are...but if you dont mentally factor in the current, you might think yer mileage just went to hell. Your pitot or paddlewheel is a basic sensor and measures your input parameter. GPS is a calculation. Theres a difference.
If you're motoring at 3 knots dead into a 3 knot current, then you're not moving. Say you're burning 3 GPH to do this.
Command Link with GPS input will tell you that you're getting 0 MPG.
Command Link with pitot input will tell you that you're getting about 1 MPG.
Which is more accurate?
Going upcurrent hurts your MPG, just like going into a headwind hurts your MPG in a car. Going downcurrent helps MPG. Command Link with GPS input will tell you all this. Command Link with pitot input will not.
If you want to use the GPS/Command Link system to get GPH vs. speed (over water) and MPG (over water), do out and back runs and average the results to cancel for any current effects. This will still be more accurate than using the pitot, which only gives you a fairly rough approximation of actual speed through the water.
absolutely, Floater. Total agreement to a point. GPS is NOT more accurate for mpg. Position? yep. Speed over ground, sure. In a moving medium ( air ( flying) or water (boating) ) nope.
Going upcurrent does not affect your miles per gallon from a standpoint of evaluation of engine or prop performance. Actually, using the info from GPS is kinda useless for accuracy there.
Picture the water you are in as a moving block of stuff travelling over the earth. If you are interested in how you are doing moving throughthat block of stuff, GPS is not accurate. It tells you the total result of the vectors of what you are doing in that block of stuff Plus/minus what that block of stuff is doing on the planet. Gps dont know that. it tells you from point to point on the earth. I dont see how it could be even close to accurate when figureing MPG.
I am just talking about MPG here. heading is a whole nuther thing people miss understanding with GPS.
Edited after your edit:
Yeah, if the runs were short and the current didnt change between the two runs.
Maybe I'm missing it. I think this sums up the whole thing:
If you're motoring at 3 knots dead into a 3 knot current, then you're not moving. Say you're burning 3 GPH to do this.
Command Link with GPS input will tell you that you're getting 0 MPG.
Command Link with pitot input will tell you that you're getting about 1 MPG.
Which is more accurate?
Going upcurrent hurts your MPG, just like going into a headwind hurts your MPG in a car. Going downcurrent helps MPG. Command Link with GPS input will tell you all this. Command Link with pitot input will not.
The gas being used is being calculated by something else--the wheel in your fuel line or by a computer calculating duty cycles on injector pulses. This will be your "variable" in the MPG equation showing how hard the motor is working; ie upcurrent v downcurrent. Are you confusing where the measurements are being derived?
If you want something for 'engine or prop performance' than MPG is just one factor of many to consider and if this is you sole metric you will not get a complete analysis.
Also, what is your point of reference to calculate 'distance'?
Your statement "...I dont see how it could be even close to accurate when figureing MPG. ..." is what I'll focus on, because it IS MOST accurate.
Land should be your point of reference, like the bottom of a river for example or the center of the earth, then MPG (by defniition is Mile Per Gallon or a representation of 'how far you travelled in miles porpotional to how much fuel in gallons it took to do it), is will be WAY more accurate with a GPS input, as opposed to a pitot tube input to, for the measurement of the 'distance travelled in miles', since pitot tubes, based on airpressure, are not linear in thier reading across speed, and ultimately both pitot tube and GPS are reallyng measure 'speed' that is then translated to 'miles' by multiplication of 'time' by some device, like your Yamaha FMS, then used in the calculation of MPG.
Now if your point of reference is 'water', like a flowing river, which I personally can not understand why someone would have this as a point of reference, then a pitot tube 'would be more accurate' in your example of 'holding steady into a current' where your boat is not travelling any distance relative to land, but is 'traveling' (a stretch in my mind) a distance through water.
Since measureing distance by GPS is more accurate than with a pitot tube (we all do agree on this right), then MPG is more accurate with a GPS reading. No Question.
I think it will help if you forget about currents/wind/other forces that 'effect your ability to travel a distance' and just focus on the fact that MPG is "The distance travelled (in miles) divided by the gallons of fuel required". If wind/current help you travel this distance it will reduce the amount of other engergy required, such a current/wind, but you still travel a specific distance (over water with the center of the earth as your reference) and use a specific amount of fuel.
I think You have absolutely no feel for navigating in the ocean. forget the land under you. the water moves. you are not driving from one milepost to another on a road. The pavement isnt drifting. You are in the water. Put a dead boat in the water, turn on the GPS, and eventually it will travel a thousand miles burning NO fuel at all.
Ok...with a zillion horsepower engine that burnt a hundred gallons just to fire up.. I could drift in the Gulf stream with the engine dead and get a million miles per gallon by your argument. Travel from Florida to the UK without burning an ounce. Right?
The water is a sliding interface between the boat and the earth. The boat is in the water, NOT attached to the earth. GPS info has NO correction for this. how far you travel on the earth is NOT how far you travelled through a moving medium between you and the earth. If you forget that concept, then you dont get the rest of it right.
as for "what I am trying to achieve", its understanding why hooking up the GPS speed over ground (SOG) to the engine computer will NOT give you true MPG for figuring fuel or engine efficiency. MPG is how far the boat pushes thru the water. GPS position is how far the boat moved over a fixed point on land. You believe those are the same...I aint gonna use you for navigation information.
You need to think about it more, thats all. I am sure the logic will become clear.
I think You have absolutely no feel for navigating in the ocean. forget the land under you. the water moves. you are not driving from one milepost to another on a road. The pavement isnt drifting. You are in the water. Put a dead boat in the water, turn on the GPS, and eventually it will travel a thousand miles burning NO fuel at all.
Ok...with a zillion horsepower engine that burnt a hundred gallons just to fire up.. I could drift in the Gulf stream with the engine dead and get a million miles per gallon by your argument. Travel from Florida to the UK without burning an ounce. Right?
The water is a sliding interface between the boat and the earth. The boat is in the water, NOT attached to the earth. GPS info has NO correction for this. how far you travel on the earth is NOT how far you travelled through a moving medium between you and the earth. If you forget that concept, then you dont get the rest of it right.
as for "what I am trying to achieve", its understanding why hooking up the GPS speed over ground (SOG) to the engine computer will NOT give you true MPG for figuring fuel or engine efficiency. MPG is how far the boat pushes thru the water. GPS position is how far the boat moved over a fixed point on land. You believe those are the same...I aint gonna use you for navigation information.
You need to think about it more, thats all. I am sure the logic will become clear.
I guess i'm just not getting this.
As you stated, water is the medium you are going through to get somehwhere. The distances between the point you left and the one you are attempting to get is static; the load the medium places on your motor may not be, and is meaured by your fuel usage. How can between two staic points, a GPS NOT be a better method of determining distance?
Connecting Yamaha Gauges to GPS
