Chart plotter shows your on land?
- Thread starter Ward H
- Start date
Just remember the words "accuracy to 3 meters". I run up a narrow twisty shallow creek to my boatyard. Did I say shallow? During the winter months, there are times I can not cross the bar into the creek with a 4 foot draft. I can be in the middle of the creek and have tracks on both sides of my present position. The only reason I made a route for the creek is to know how much longer the pucker factor runs!
The good news is the boatyard is also the local TowBoatUS and he can come get me if I mess up.
True, when we are talking about accuracy issues within 3 meters to electronically guide our boats something is wrong.Just remember the words "accuracy to 3 meters". I run up a narrow twisty shallow creek to my boatyard. Did I say shallow? During the winter months, there are times I can not cross the bar into the creek with a 4 foot draft. I can be in the middle of the creek and have tracks on both sides of my present position. The only reason I made a route for the creek is to know how much longer the pucker factor runs!
This is a job for EYEBALLS and human judgement. If you cannot or will not rely on that for safe transit, DON'T GO.
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Heads down navigator!
I would note that most boats that are not yours do not show up on your chart plotter. You might want to stop watching the GPS and keep a good look out.
now if you are in the middle of the ocean and using GPS (or any other autopilot method) you pretty much have to go to sleep but there is not much out there so not much of a problem. In confined waters......... the same cannot be said.
I would note that most boats that are not yours do not show up on your chart plotter. You might want to stop watching the GPS and keep a good look out.
now if you are in the middle of the ocean and using GPS (or any other autopilot method) you pretty much have to go to sleep but there is not much out there so not much of a problem. In confined waters......... the same cannot be said.
I followed JackDaw's recommendation and reported the error to Garmin. Here is their reply:
"Good afternoon,
This is a 1:40,000 scale chart. The optimal zoom, based on its resolution, is 500 feet. Keep that in mind. Still, even at 500’, you would see this in this track.
The source chart is NOAA 12324. We are reproducing it as it is on the NOAA chart, the official source data.
I will send a report to our marine people to document this. They will probably notify NOAA. I cannot guarantee what/when a change might happen in the future. We stay faithful to the official hydrographic office data. Usually they are VERY good at what they do, but I can see what you are talking about at this position.
Best regards,
Loy
Garmin Cartography Administration"
Looking at the shoreline in that area it is easy to see/guess that the shoreline has moved over the years since the chart was drawn.
I'll do what Stu suggested and turn a good track into a good route and save it in case I ever really need it, keeping in mind GPS accuracy. I doubt I ever will but I like to plan ahead just in case.
And there is no heads down navigation on this boat, especially in this channel. The town boat ramp is at the channel's narrowest point, about 30' wide. The spot was probably chosen so the ramp is somewhat protected by the mud flat on the other side.
Yesterday three kayakers popped out of the ramp from behind a boat tied to the bulkhead, one after the other, without looking for traffic. They were lucky I had time to hit reverse as the last one cleared my bow by about 6'.
"Good afternoon,
This is a 1:40,000 scale chart. The optimal zoom, based on its resolution, is 500 feet. Keep that in mind. Still, even at 500’, you would see this in this track.
The source chart is NOAA 12324. We are reproducing it as it is on the NOAA chart, the official source data.
I will send a report to our marine people to document this. They will probably notify NOAA. I cannot guarantee what/when a change might happen in the future. We stay faithful to the official hydrographic office data. Usually they are VERY good at what they do, but I can see what you are talking about at this position.
Best regards,
Loy
Garmin Cartography Administration"
Looking at the shoreline in that area it is easy to see/guess that the shoreline has moved over the years since the chart was drawn.
I'll do what Stu suggested and turn a good track into a good route and save it in case I ever really need it, keeping in mind GPS accuracy. I doubt I ever will but I like to plan ahead just in case.
And there is no heads down navigation on this boat, especially in this channel. The town boat ramp is at the channel's narrowest point, about 30' wide. The spot was probably chosen so the ramp is somewhat protected by the mud flat on the other side.
Yesterday three kayakers popped out of the ramp from behind a boat tied to the bulkhead, one after the other, without looking for traffic. They were lucky I had time to hit reverse as the last one cleared my bow by about 6'.
On Land
Here is a pic of my plotter showing a purple line from a couple of months before and where the plotter located me on a different day.. I sent this to Garmin and never got a reply.. Something a little wonky since I distinctly remember the purple line being in the center of the bayou when the line was being drawn.
EDIT: Oh, I was centered in the right side waterway (bayou) when the picture was taken.. an error of 411 feet showing..
Here is a pic of my plotter showing a purple line from a couple of months before and where the plotter located me on a different day.. I sent this to Garmin and never got a reply.. Something a little wonky since I distinctly remember the purple line being in the center of the bayou when the line was being drawn.
EDIT: Oh, I was centered in the right side waterway (bayou) when the picture was taken.. an error of 411 feet showing..
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