I am having some issues with my Garmin Geko GPS and thought the collective knowledge may be able to help, and yes I know I should get a Navi but the purse stings are pulled excedingly tight.
The GPS performs great when I'm on my Formula board with no suspicious speeds or times. However once I am on my iSonic 125 I seem to be getting some strange results. I think the results relate not so much to the board but to my ability and the fact that on the iSonic I fall in a lot and on the Formula board I dont.
When I put my track into KA72 (thanks Dylan) and a strange result appears, one which I am sure is beyond my ability, I go to Realspeed and usually there is a red line that joins 2 points which I cant remove by using the 'Delete Invalid' command.
My real question is what is causing this? Can it be that the GPS loses signal when I am in the water and then takes some time to pick it up again, creating the illusion that I am a 'Gun' sailor?
Any other ideas welcome, with if possible a way to fix it other than spend all my waking hours looking at every time in Realspeed.
Cheers

Yep I get that sometimes on the navi, shows up as a ripper alpha

It generally has a high speed a zero then another high speed, I just highlight the 3 and delete, it then sorts itself out.

Hi Geoff,
Sound like what you suspected. Water blocks radio signals. You get spikes and errors when you fall in. It takes time to get the position back and correct. This is more of an issue with the older GPS that only record the positional data.

I suggest asking around to see if anyone has a GT-11 that they don't need anymore. I know some have gone to good homes to enthusiastic caring owners at great deals.

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sailquik said...


I suggest asking around to see if anyone has a GT-11 that they don't need anymore. I know some have gone to good homes to enthusiastic caring owners at great deals.

Thanks guys. I thought I had it pegged but wasnt sure. Was a little embarrassing as it got posted and a few guys thought I was becoming a 'Gun' sailor. Has since been corrected and my PB now is once more achievable.
If anyone has a GT11 that needs a good home, for a reasonable price I'm interested. At least the Garmin will be a backup.

I think the garmin has a dead reckoning filter. If it looses signal it "assumes" you are continuing on the prior path. Once you are back up and sailing again and the gps gets a new signal it realizes its "assumption" is wrong and it tracks back to the correct position (usually at 999 knots). The Navi has a "record only on (satellite)fix" function which solves this.

The answer is . Don't fall in!

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yoyo said...

I think the garmin has a dead reckoning filter. If it looses signal it "assumes" you are continuing on the prior path. Once you are back up and sailing again and the gps gets a new signal it realizes its "assumption" is wrong and it tracks back to the correct position (usually at 999 knots). The Navi has a "record only on (satellite)fix" function which solves this.

The answer is . Don't fall in!

Sounds exactly like what I am seeing in Realspeed. Track stops, then red lines back to the new point.
And yes I know! If only.