GPS Speedo

[carlos515]

late to the party however this is your best answer.

No offence but if you are 'in tune' with your motor speed is not generally a concern. I really do not care how fast i am going i want my RPMs right, sound in my ears cool, and just humping down the water. If I sense something off, I get my phone out to check gps speed.

No offence taken. The boat is new to me, so I really am not in tune to it yet. I am more interested in knowing my wake speed, so I do not get bothered by the OPP.

 

[jimmbo]

I wouldn't trust a GPS Speedo on a River, or any body of water that has a Current. Or for any Tournament/Competition Skiing Event

 

[Mc Tool]

I wouldn't trust a GPS Speedo on a River, or any body of water that has a Current. Or for any Tournament/Competition Skiing Event

Well you absolutely can trust a gps speedo as long as you understand its giving you speed over ground not speed thru water , and when Im navigating my way from the ramp to my destination the distance between way points ( where I change direction due to coastline or hazards ) is displayed as distance over ground and I can then calculate my eta and current or tidal flow becomes irrelevant . If you want speed thru water you can compare your pitot tube or paddle wheel against your gps whilst in still water and then factor in any discrepancies when in moving water ,ie
If your pitot or paddle is +2km/hr off the mark in still water at your desired trolling speed you simply troll at an (pitot /paddle) indicated speed 2km/hr faster than you actually want to go.......but I personally couldnt be arsed with all that and go by at what speed the lure performs best at by holding the rod as far forward as I can and observe the lure at the side of the boat and as long as the lure doesnt break the surface it will perform the same regardless of depth . And ,anyhow fishing is supposed to be relaxing so .............

 

[airshot]

I wouldn't trust a GPS Speedo on a River, or any body of water that has a Current. Or for any Tournament/Competition Skiing Event

Any type of current in the water will give you false speed readings on paddle wheels or any pressure type speedo. GPS is the most accurate speed when going from point A to point B, wind, current has no effect on GPS. However when trolling lures, water speed including current can make a difference on lure action, that is why folks often add them ..

 

[jimmbo]

Wrong, the GPS will not give a true Water Speed, when there is a Current. It will give an Accurate Speed, in regards to the Ground below

 

[jlh3rd]

well...neither does a paddle wheel or a pitot tube....It's all relative (remember einstein)
If a current is 5 mph but the boat is anchored, the standard speedo will read 5mph +/-.....GPS says O mph.....so which one is more right?...or accurate for the intended purpose.
Pull up the anchor, standard speedo goes to 0....GPS says 5 mph....same question.

throw in the motor, against current, pull anchor....get standard speedo to read 5mph.....you are going nowhere at 5mph.....the gps says 0.

GPS gives the better observation as to what we are doing in the real world.
I prefer GPS. I don't care about my water speed.

someone mentioned airspeed in relation to airplanes and waterspeed to boats as somehow related . It is not. Apples and oranges.
Airspeed is a critical if not the main component of operating an airplane safely. Groundspeed is irrelevant ...except of course in flight planning.
waterspeed is not critical to a boat operation. A boat doesn't sink with zero waterspeed.

 

[jimmbo]

Waterspeed is Imprtant/Critical to several Boating Activities

 

[redneck joe]

 

[ratdude747]

Waterspeed is Imprtant/Critical to several Boating Activities

But the relation to ground (GPS) speed may be close enough depending on the activity? Example being pulling a tube/skier on a lake or river... if the current is enough that the error introduced becomes significant, then (at least where I boat and pull such things) it's probably not a good condition to run in. A few mph isn't a hill of beans difference in that case.

 

[boscoe99]

someone mentioned airspeed in relation to airplanes and waterspeed to boats as somehow related . It is not. Apples and oranges.
Airspeed is a critical if not the main component of operating an airplane safely. Groundspeed is irrelevant ...except of course in flight planning.
waterspeed is not critical to a boat operation. A boat doesn't sink with zero waterspeed.

I am that someone.

Point was to indicate that GPS speed and pitot tube/paddle wheel speed are for two different measurements. One cannot be compared to the other. One is not inherently any more accurate than the other.

If a boater is not aware of what is going on with his boat with respect to speed then certainly GPS speed will keep him happier.

 

[airshot]

Wrong, the GPS will not give a true Water Speed, when there is a Current. It will give an Accurate Speed, in regards to the Ground below

You have that backwards, GPS uses satellites and measures distance from one point to another over time. Speed is the time it takes to travel over a certain distance, current in the water will speed you up or slow you down, the GPS only gives you time between reference points.

 

[jimmbo]

GPS does not show the Speed with regards to the Water, if there was an 8mph current, and Pitot Speedometer says 28mph. In one direction, going against the Current, the GPS reports 20mph, 180 degrees the other direction, with the Current, it would report 36mph

 

[Mc Tool]

GPS does not show the Speed with regards to the Water, if there was an 8mph current, and Pitot Speedometer says 28mph. In one direction, going against the Current, the GPS reports 20mph, 180 degrees the other direction, with the Current, it would report 36mph

Its not supposed to or claims to give you speed thru water . Marine charts are distanced in nautical miles and speed is in knots ....not blimmin how fast jimmbo thinks the water is flowing . As per above ...yes jimmbo the gps would report 20mph in one direction and 36mph in the opposite direction coz THATS HOW FAST YOUR GOING . Everyone else in the world uses nautical miles for distance and knots for speed whilst navigating the high seas . You wanna be careful least you sail off the edge of the world while your muckin round trying to figure out how fast your goin downstream.

 

[jimmbo]

Gee the poor waterskier/wakeboader, especially in a Tournament, is gonna have an Eff of a time if a GPS Speedo is used instead a calibrated Pitot Speedo, even a one mph error, will cause problems

GPS speedos can also bring Planes Down, as Air Speed is what keeps Planes in the Air, so with a Tailwind, a Plane will be doing fine on the GPS Speed, but might be very close to stalling cause the Air Speed is not fast enough

 

[Mc Tool]

Gee the poor waterskier/wakeboader, especially in a Tournament, is gonna have an Eff of a time if a GPS Speedo is used instead a calibrated Pitot Speedo, even a one mph error, will cause problems

GPS speedos can also bring Planes Down, as Air Speed is what keeps Planes in the Air, so with a Tailwind, a Plane will be doing fine on the GPS Speed, but might be very close to stalling cause the Air Speed is not fast enough

We aint talking planes tho ,and I dont know anyone who skis or trolls behind a plane.
Pitot tubes and paddle wheels were put on boars waaaaaaay back when there was nothing else , and if you didnt have a gps now you wouldnt know how inaccurate your pitot was or be able to calibrate it .
In any event you could not use an air speed indicator to calculate an eta because the distance between airfields doesnt change if the wind changes speed or direction when your halfway there

 

[jimmbo]

You don't need a GPS to calibrate a Pitot Speedo, in fact, using that to Calibrate it would likely make it inaccurate, unless it was done in a Slough, or a Pond where there would be no Water Flowing through it. Pitot Speeds are simple Pressure Gauges, bound by the Laws of Physics

As for Waterskiing behind Planes, that was quite common 100 yrs ago,
GPS Speed is not the Safest Way to fly a Plane. Oh, it will show where the Plane is, but as I said, Air Speed is far more Important than Ground Speed, in fact it is Critical in keeping the Plane in the Air.

 

[Mc Tool]

You don't need a GPS to calibrate a Pitot Speedo, in fact, using that to Calibrate it would likely make it inaccurate, unless it was done in a Slough, or a Pond where there would be no Water Flowing through it. Pitot Speeds are simple Pressure Gauges, bound by the Laws of Physics

As for Waterskiing behind Planes, that was quite common 100 yrs ago,
GPS Speed is not the Safest Way to fly a Plane. Oh, it will show where the Plane is, but as I said, Air Speed is far more Important than Ground Speed, in fact it is Critical in keeping the Plane in the Air.

Ugh , I give up
'cept Id like to hear about you skiing behind planesthat would have to be a young mans game

 

[redneck joe]

 

[BWR1953]

 

[airshot]

Gee the poor waterskier/wakeboader, especially in a Tournament, is gonna have an Eff of a time if a GPS Speedo is used instead a calibrated Pitot Speedo, even a one mph error, will cause problems

GPS speedos can also bring Planes Down, as Air Speed is what keeps Planes in the Air, so with a Tailwind, a Plane will be doing fine on the GPS Speed, but might be very close to stalling cause the Air Speed is not fast enough

That is why they call it " airspeed" on a plane ! They also use a GPS for ground speed. Different names for different type of speed.