Re: [bolger] Re: Speed via GPS
BO>Speed measured by GPS is subject to various kinds of errors. The
BO>degraded signal that we have had to put up with for the past couple
BO>years causes indicated speed to wander up and down by a knot or so at
BO>sailboat speeds.
BO>I read in the paper that domestic interests are causing the military
BO>to stop degrading the signal over the USA, so we should see better
BO>positions and more accurate speeds this summer.
BO>Peter
The signal degradation was removed at 0000hrs May 1. The difference is
amazing,particularly the rapidity with which locational information
stabilises and the fact that the height ASL estimates now bear a close
resemblance to reality. The GPS should now be reasonably accurate as a
speedo. But you should be doing your navigation or coastal pilotage
without such things, so you're fully competent even in the absence of
batteries <g>.
Tim & FT2
SquareBoats!http://www.ace.net.au/schooner/sbhome.htm
BO>degraded signal that we have had to put up with for the past couple
BO>years causes indicated speed to wander up and down by a knot or so at
BO>sailboat speeds.
BO>I read in the paper that domestic interests are causing the military
BO>to stop degrading the signal over the USA, so we should see better
BO>positions and more accurate speeds this summer.
BO>Peter
The signal degradation was removed at 0000hrs May 1. The difference is
amazing,particularly the rapidity with which locational information
stabilises and the fact that the height ASL estimates now bear a close
resemblance to reality. The GPS should now be reasonably accurate as a
speedo. But you should be doing your navigation or coastal pilotage
without such things, so you're fully competent even in the absence of
batteries <g>.
Tim & FT2
SquareBoats!http://www.ace.net.au/schooner/sbhome.htm
The Cheap Info Graphic for the difference with SA off (as it is now)
is
in the file vault.
is
in the file vault.
At 02:22 PM 05/03/2000 EDT, you wrote:
I have been flying, driving and sailing with GPS for over 6 years and have
never seen any speed problems. I have cross checked GPS with Loran C,
speedometer and Aircraft DME and been totally satisfied.
Tim
><< Speed measured by GPS is subject to various kinds of errors >>List,
>
I have been flying, driving and sailing with GPS for over 6 years and have
never seen any speed problems. I have cross checked GPS with Loran C,
speedometer and Aircraft DME and been totally satisfied.
Tim
> Almost burst my bubble!:-) This is the second time that gpsmeasured 7
> knots while on a beam reach.Don't get me wrong, I'm not suggesting you weren't screaming along,
just cautioning you not to rely on the decimal points.
:-)
In a message dated 5/3/2000 8:57:19 AM Eastern Daylight Time,
pvanderw@...writes:
<< Speed measured by GPS is subject to various kinds of errors >>
Almost burst my bubble!:-) This is the second time that gps measured 7
knots while on a beam reach. Not bad for a box full of sand and lead. Steve (
Landroval)
pvanderw@...writes:
<< Speed measured by GPS is subject to various kinds of errors >>
Almost burst my bubble!:-) This is the second time that gps measured 7
knots while on a beam reach. Not bad for a box full of sand and lead. Steve (
Landroval)
Sez Tim:
The signal degradation was removed at 0000hrs May 1. The difference is
amazing,particularly the rapidity with which locational information
stabilises and the fact that the height ASL estimates now bear a close
resemblance to reality. The GPS should now be reasonably accurate as a
speedo.
Sez I:
Yes - before if you decided to fly your sailboat like a cruise missile,
you'd nose into the turf long before arriving.
Now when I'm afloat on the Chesapeake, the GPS tells me I'm near sea
level. Awesome.
Well, it was worth the $100 for the little Blazer I bought ...
The signal degradation was removed at 0000hrs May 1. The difference is
amazing,particularly the rapidity with which locational information
stabilises and the fact that the height ASL estimates now bear a close
resemblance to reality. The GPS should now be reasonably accurate as a
speedo.
Sez I:
Yes - before if you decided to fly your sailboat like a cruise missile,
you'd nose into the turf long before arriving.
Now when I'm afloat on the Chesapeake, the GPS tells me I'm near sea
level. Awesome.
Well, it was worth the $100 for the little Blazer I bought ...
> The signal degradation was removed at 0000hrs May 1. Thedifference is
> amazing,particularly the rapidity with which locational informationclose
> stabilises and the fact that the height ASL estimates now bear a
> resemblance to reality.A friend of mine who is an Air Force veteran told me that the purpose
of the signal degrade was primarily to reduce the accuracy of the ASL
numbers. That was enough to make it unreliable for the task of
steering a nuclear warhead to hit the top of a missle silo exactly.
PHV
> >p.s. Landroval was out in strong 15 mph winds yesterday - and thegps
> >clockedSpeed measured by GPS is subject to various kinds of errors. The
> >us at 6.6 - 7.1 knots on a beam reach - with full sail.
degraded signal that we have had to put up with for the past couple
years causes indicated speed to wander up and down by a knot or so at
sailboat speeds.
I read in the paper that domestic interests are causing the military
to stop degrading the signal over the USA, so we should see better
positions and more accurate speeds this summer.
Peter
In a message dated 5/3/2000 12:06:56 AM Eastern Daylight Time,
ewhaile@...writes:
<< Holy smokes! The best I've done is six. So just exactly how much extra
ballast have you added at this point? How much does the ship weigh?
By the way, what with all this MJ redesigning business, I'd like to go on
record as being highly pleased with the original trapdoor rudder. I had my
initial misgivings, I admit. Bennett can tell you. But it really works well
here and I love all that space aft. I have worked out a very nice pop-off
catch so the door doesn't bubble up and flood at all.
Ed Haile
know is that the van handles the weight - so I'm not concerned. My total
ballast is 825 lbs - all in the ballast tanks. I am real pleased with the
feel of the boat.
The aft portion of our cockpit is covered by a bimini - this is one reason I
opted away from the trap door. I'm looking forward to seeing the new plans
and will give the new twin rudder system a try - since I suspect they will be
of shallower draft as well as allowing me to move the location of the
outboard back to the center. I am very eager.
She was flying on Saturday - and I suspect my sailmaker gets most of the
credit for that. we also had plenty of 90 degee tacks - tho 50 degrees off
the wind was faster than 45 degrees.
steve
ewhaile@...writes:
<< Holy smokes! The best I've done is six. So just exactly how much extra
ballast have you added at this point? How much does the ship weigh?
By the way, what with all this MJ redesigning business, I'd like to go on
record as being highly pleased with the original trapdoor rudder. I had my
initial misgivings, I admit. Bennett can tell you. But it really works well
here and I love all that space aft. I have worked out a very nice pop-off
catch so the door doesn't bubble up and flood at all.
Ed Haile
>>Ed - I have not weighed Landroval so I don't know what she weighs - All I
know is that the van handles the weight - so I'm not concerned. My total
ballast is 825 lbs - all in the ballast tanks. I am real pleased with the
feel of the boat.
The aft portion of our cockpit is covered by a bimini - this is one reason I
opted away from the trap door. I'm looking forward to seeing the new plans
and will give the new twin rudder system a try - since I suspect they will be
of shallower draft as well as allowing me to move the location of the
outboard back to the center. I am very eager.
She was flying on Saturday - and I suspect my sailmaker gets most of the
credit for that. we also had plenty of 90 degee tacks - tho 50 degrees off
the wind was faster than 45 degrees.
steve
Hi Steve,
Holy smokes! The best I've done is six. So just exactly how much extra
ballast have you added at this point? How much does the ship weigh?
By the way, what with all this MJ redesigning business, I'd like to go on
record as being highly pleased with the original trapdoor rudder. I had my
initial misgivings, I admit. Bennett can tell you. But it really works well
here and I love all that space aft. I have worked out a very nice pop-off
catch so the door doesn't bubble up and flood at all.
Ed Haile
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Holy smokes! The best I've done is six. So just exactly how much extra
ballast have you added at this point? How much does the ship weigh?
By the way, what with all this MJ redesigning business, I'd like to go on
record as being highly pleased with the original trapdoor rudder. I had my
initial misgivings, I admit. Bennett can tell you. But it really works well
here and I love all that space aft. I have worked out a very nice pop-off
catch so the door doesn't bubble up and flood at all.
Ed Haile
>p.s. Landroval was out in strong 15 mph winds yesterday - and the gps________________________________________________________________________
>clocked
>us at 6.6 - 7.1 knots on a beam reach - with full sail. She was rock steady
>-
>not a tense moment even in gusts. The increased ballast continues to
>inspire
>confidence.
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