#1 - whats the correct way to GPS runs ??

#2 - whats one of the cheapest - reliable tools for GPSing.

[This message was edited by sandman on Sun October 19 2003 at 08:51 PM.]

The cheapest way is to buy a Garmin E-Trex GPS for $100 and some change (available at Best Buy). I have a pocket on my ski vest so I put it in my pocket and find some smooth water. I personally don't do anything more than put as much weight on the back of the ski and still have my feet on the ski and my butt on the seat. (Superman position doesn't count). Then I simply look at the "Max Speed" function on the GPS that tells me the fastest I went. I usaully reset the max speed and try again.

Ya really need to make p***es in opposite directions.
It is possable to go faster in one direction than the other.
Several thingh factor into this. Satalite position,cloud cover, current or tide, wind.

so it is best to average your speeds.

wind and current will effect the outcome of your run it measure distance over land/water. i doubt cloud cover will make a difference. it still measure from point 'a' to point'b' how long it took and how fast.

Hey charles if im still employed after the first of the month you wanna hook for some ocean/surf some time soon. I should find out tomorrow about my job.

have had cloud cover affect my gps, on my nav system in my car and on the gps on the water. takes awhile for the signal to come back when its overcast

2000 1200gpr DOWN WITH THE SICKNESS

Good GPS units can be had for under $130. Make sure you do several runs. Sometimes, you'll get an oddball reading that for some reason puts your speed at several mph higher than it should. Maybe just a gps hiccup.

I just bought the Garmin Geko 201 at West Marine. I think it's the intended replacement for the e-trex series. It's a tiny unit, the smallest I have seen yet. It is WAAS enabled for extra accuracy and tells you the accuracy of it's measurements which is nice for measuring true top speed. $140.

Academy has better prices than Best buy. When I bought my e-trex it was $30.00 dollars cheaper. Very good and reliable unit. Just wrap it in a towel or some foam and put it in the glove box and it will work fine. And yes if you have a current where you gps, you will need to go both directions and compare the two. Some web sites have plenty of info on gps's. Check the web. I think that casio even has a watch that has a gps on it. rp

http://home.austin.rr.com/flyingfossil

Oh yeah, here's my tip for GPSing:

If yours doesn't float, go buy one of those cheap, $5 neoprene cases for a cell phone. It works, and makes the darn thing float! I cut a little window in my case so I could see the readings.

thanks all for input - I usually don't post after every reply - sometimes there no real reason too!

sandman

Wide, long radius turns can give false GPS readings. If you get the highest speed in a long turn than that reading is no good.

GroupK reported this and I can say for certain that you can get false readings on the peak indication when turning. I saw a 67.5 MPH reading in a long turn, when my ski only goes 66.5 MPH best.

GPS in a straight line only for actual readings.

Make four attempts per direction, take out the worst and the best, and make an average of the two others, every time use the same ammount of gas for every attempt, do not pee between atempts.
The perfect way being to try every possible heading, there are 360 deg, that's 4 attempts per attempt, 1440 runs, should keep you busy for a while
11

2003 STXR : S/S single piper dynoed at 178hps, R&D sponsons/grate/plate, 14/24, UMI fat. 68mphs. FPP/MP soon.
2003 SXR : 50.8mphs. FPP/MP/NOVIs soon

I did testing a couple of years ago with both a Garmin Etrex Vista, and a Garmin 3. The 3 was mounted and the Vista was wrapped in a glove in the glove compartment. The Etrex would routinely read 3-5mph HIGHER than the 3. I duct taped the Etrex to the handlebar, and they would read identical on almost every run <1mph.

Maybe it was bouncing around in the glove compartment throwing off the speed?

mark c
http://www.hydrotoys.com/gpr/current.html
02 GP12R Stage "Mc"
96 XP-FOR SALE, MAKE OFFER.
01 FZ-1
00 Sportsman 500
02 Bomb DS650 Baja-FOR SALE, MAKE OFFER.

Hows it goin Mark? Did you use a rag or something to buffer between bars & unit?Mine seems to shut down reeeaaalll easy! Thanks

If you so much as move a GPS any amount up and down it will give you an additional 2-3 mph and if the movement is bad enough 6 mph is not out of the questiojn. Just take the GPS an hold it in your hand while driving your car on cruise control, once you have a steady reading on the GPS move it vertically and you'll see the error being introduced right before your very eyes. The error will also be introduced when on handlabar mounts as soon as you porpoise any amount. So don't take your GPS readings too seriously boys until you do a couple of passes in which your boat is truly steady from beginning to end of the run. It really doesn't matter how much you average in 20 different directions, the moment you porpoise you will be introducing error.

Mario