Dose river current affect GPS speed?

[Danhercules]

I say yes. Here is why.
GPS is LAND speed. Your on moving water, kinda like a tread mill. The tread mill says your going 3 mph, but your not moving. Thats how I see it.
So if thats the case, Down river speeds will register faster than your boat really is, and up river speeds will register slower than you boat really is.
Can you then average the two numbers to get a TRUE speed?
I was at 69.8 MPH on a upriver pass with a GPS, was I going faster than that if I were to register water speed?
Some say it dose not matter, Why?

[Squirtcha?]

It's o.k. buddy....................you can call it 70 mph!

[Wet Dream]

GPS measures your speed against a fixed point. It doesn't care if you are on water or not. You will have 2 different readings, one up river which will be slower and one down river which will be higher. You can average them, but if you want to get truely accurate, you'll have to know the speed of the water in several locations of the river. Narrowing banks, deeper runs, shallows and bends all change the speed of the water.

[Danhercules]

Originally posted by Squirtcha?
It's o.k. buddy....................you can call it 70 mph!
Its faster than that buddy. Just no number yet. That was way full of stuff. Next I need a loader.

[Squirtcha?]

I was just razzin ya bud. I know you're running faster than 70.
Next I need a loader.
You'll always need something...............at least I do!
Good explanation on the gps thing by Wetdream.
Oh yeah, did ya get the miss straightened out? I'm assuming you did, and if so what was the cause of it?

[roostwear]

The testing I've been doing has been corrected for current. I figure (right or wrong) that if I'm moving 2.4 mph shut down, that when I GPS downriver, I deduct current speed. Lately, I've been backing up with upriver speeds and adding current speed. The 2 figures have been pretty close. Of course I can't break 70, so it's all academic :D
Roost (still trying to break 70) wear

[OMEGA_BUBBLE_JET]

why not take it to a lake to get accurate numbers? lakes don't have currents. Or is the river your only option out west.
Omega

[roostwear]

Lakes out here are infested with yachts. With little freeboard on a 18 footer, I stay on the river. My place is at the river, so it's convenient.:D

[MAXIMUS]

Absolutly NOT!!!!! Just make sure when you GPS your boat that you are going down river! Uhhh.... it creates less friction on the pad!!;) :D :D :D

[cyclone]

just do like I do: gps it on the trailer during the drive to the river. the motor is all for show I swear. :D

[MudPumper]

I always GPS down river. Makes me feel better about all the money I spend and the mph gains I don't see!!! LOL:D

[GM Killer]

Originally posted by Danhercules
Its faster than that buddy. Just no number yet. That was way full of stuff. Next I need a loader.
Dan
Where in Norco are ya? I see quite a few boats pass by my place. I have a few loader grates in the garage just takin up space. What ya need?
GM Killer

[Danhercules]

I need a loader that will load water in my pump!!!!!!
I have no clue.
I live in the "bluffs", the "other side". On Vine off Corydon, near River. Give me a shout and stop by for a beer!!!! Check your PM;s

[mickeyfinn]

just take your gps reading as your travel ACROSS the river. :D

[Danhercules]

So is that the Tacking method of getting a GPS speed?