<br /><br /><br />tommays
<br />Just kidding around. It only seemed like an odd comparison to me. I hope I'm not the only one who sees a little humour in it. 
Let's Not Forget Fishin',......
<br /><br />As Stated repeatedly,..... It's More about What you wish to Measure,........<br /><br />GPS,.. If you wish to measure How Fast you are moving,.. Around the Globe.........<br /><br />A Trolling Spoon Doesn't Care how fast it's traveling around the Earth,..........<br />What Matters is,........ How Fast it's moving thru the Water ......<br /><br />'ell,..... I'm running 2 paddlewheels,+ GPS......They Rarely Agree,.... Due to Currents............
<br /><br />Having the air tube, paddle wheel, and GPS on mine (none of which ever agree unless I'm docked) it sure ends up getting confusing. So I add them up, divide by 3 and square root the average, and make sure it corresponds to the tri dimensional attributes of the girth of the moon, sun, and earth by cubing their circumference and and and...smile at my lack of mathematical ability and at the absurdity of the whole thing!<br /><br />As Bondo and others have mentionned, I must agree that the paddle wheel's advantage is best in measuring actual movement in the water where 1/2 mph could be too much or too little ...especially trolling.<br /><br />So I guess in the end it depends on what kind of speed you want to measure and how much you want to pay for that. I really like having the speedometer with the sonar since I'm always checking for water depth anyway...either fishing or just wanting to avoid hitting bottom.<br /><br />The GPS is great too in locating fishing spots and is very accurate in measuring general speed.<br /><br />In the end, I suppose just a plain old paddle wheel speedometer on its own is fine too if you don't care about any of the other stuff.
<br /><br />A factor concerning my "while climbing inaccuracy" claim may be signal losses, as when climbing a grade there is more likelihood of losing one or two satellites behind whatever you are climbing. I use my 176C on both the truck and the boat (same unit). On flat land the difference between the truck speedo and the GPS speedo is negligible and consistent. While climbing or descending I see pretty wide swings, sometimes as much as 5 MPH either way. Never seen that while on the water or driving horizontally. I also recall reading in my first unit's manual that altitude was the least accurate piece of info.<br /><br />Think about it this way. If you put a GPS on a rocket that was going straight up, what speed would it record? Up speed? Or horizontal progress, "0"? Kinda getting into theory of relativity stuff here, no? But again, while driving basically alone (four asleep passengers) for miles on end, I entertain myself and keep myself awake, by noodlin', changing screens and contemplating data. The good news is that I actually have a life once they wake up
<br /><br />now for most everything else GPS wins for me<br /><br />QC the up and down is bad becasue they dont want you useing them in aircraft which we all know somebody will be stupid enough to try <br /><br /><br />tommays
