Endurance.Net Ridecamp Archives

Susan,
Good grief...a GPS is a good tool and you just said so yourself. My
contention is that in the hands of a careful user a good GPSMap series 76
or 60 will give results within 2-5% short and I can prove it. Just
because you encountered a ride that was too long does not mean that the
problem was just because of the GPS. The GPS operator was also not up to
the task. Tools are only as good as the people who use them.

You mentioned the use of a wheel to measure the trail. On a hard flat
surface some wheels can measure within 1% but on rough terrain the errors
go nuts. The wheel now starts measuring over rocks and down into
depressions that are completely passed over by the horse's hooves. I just
did a quick test with my wheel, a large all terrain type, by putting a 12
foot tape on the sidewalk and placing red bricks to simulate fist-sized
rocks (2.5"highx4"wide) every 3 feet. 0=no brick,
3,6,9,12=bricks. After going over the brick at 12ft the wheel said 13+
feet. That is an 8% error long without any dips which would increase the
error. If the operator decides to wiggle sideways around the bricks the
wiggle causes the same error. Meanwhile the horse has bypassed the bricks
and sideways wiggles and traveled 12 feet not 13. That was a crude test
and of course the trail has many other obstacles that cause wheel errors
both long and short but you get the idea, a wheel is no more accurate
than a good GPS used by a careful operator. 

Lastly it seems that a surveyor, me, that has been measuring all types of
land with many different tools for 40+ years has no credibility with you
since you are dead set against any possibility that a GPS, even in the
hands of a careful operator, can measure an endurance trail. I know you
have experts that have denounced the use of a GPS and for the trails that
they know were measured incorrectly they are justified in their
criticism. To then cast out all GPS usage because of the previous
improper use of unsuitable units and their resulting incorrect data is
ridiculous. GPS data is not perfect but neither is any other method. If
used carefully and checked with maps and other software the results can
be within 2-5% which gives a RM another good tool to measure their trail
with the added bonus of really great maps.
Don Huston



At 06:17 PM 3/22/2007 Thursday, you wrote:
> Don,
> I'm sorry because the words of experts mean nothing to you.  As
> Randy noted, a 50 mile ride should ride as a 50.  A GPS is a good
> tool and that's how I use mine...same as my HR monitor.  However, I
> depend on neither.
>  
> As I said, 35 miles in 8 hours of trotting and cantering is not
> correct.  That's not a feeling; that is fact.  Personally, I'm
> tickled pink you've not experienced this.  This particular ride was
> several years ago now.  As Angie pointed out, it lost several riders
> because it was WAY long.  I suppose a rider with 25,000 miles under
> her belt (not me) that says the trail is long means nothing to you as
> well since you are dead set on defending the use of a GPS for measuring
> an endurance trail.  
>  
> A person needs to do what he feels is right.  The RM used a wheel to
> measure 100% of the trail the following 2 years and the times reflect
> that accuracy just as the times reflect the inaccuracy of the trail
> measured only using a GPS.
>  
> For what it's worth, posting a private message on a public forum is
> rude.
>
>
> Semper Obliquo (Always
> aside),
> Susan [Young], The Princess of Pink
> Glenndale Grace Farm, Ft Gibson, Oklahoma U.S.A.
> "Ride on! Rough-shod if need be, smooth-shod if that will do, but
> ride on! Ride on over all obstacles, and win the race!" - Charles
> Dickens (1812-1870)

Don Huston at cox dot net
SanDiego, Calif