GPS questions

[robq]

Hi all,

 

I had a fairly unpleasant experience on friday last week whilst out fishing, when I set off ( only 300 yards out) visibility was a bit murky but probably around 1/2 a mile. However after an hour or so fishing it was down to 40 yards or so, not a problem as I had my GPS and compass I thought. However at the end of one of my drifts the GPS lost its satellite fix leaving me not knowing my position !! and also gave me an assumed position about a mile from where I knew I was

 

Anyway I trusted my instincts as to where I was certain I actually was and used the compass to find my way back in ( succesfully ). back on the beach the GPS didnt pick up another fix for around half an hour

 

I know that nobody should ever rely on a GPS as their only source of navigation but I was alarmed by this unreliability. I have the lowrance I finder go 2 which I bought for trekking last year and assumed that it would be ok for inshore fishing ?? I have used it twice before with no problems !!

 

What I would like to know is-

 

Is losing a fix like that a common occurance ?

Is the signal interupted by thick fog ? surely that is when its most valuable ??

Would I be better off and would I see an advantage in spending a lot of money on a top of the range nautical handheld GPS ?

 

Thanks in advance for any help and advice

[Steinbeisser]

Hi all,

 

I had a fairly unpleasant experience on friday last week whilst out fishing, when I set off ( only 300 yards out) visibility was a bit murky but probably around 1/2 a mile. However after an hour or so fishing it was down to 40 yards or so, not a problem as I had my GPS and compass I thought. However at the end of one of my drifts the GPS lost its satellite fix leaving me not knowing my position !! and also gave me an assumed position about a mile from where I knew I was

 

Anyway I trusted my instincts as to where I was certain I actually was and used the compass to find my way back in ( succesfully ). back on the beach the GPS didnt pick up another fix for around half an hour

 

I know that nobody should ever rely on a GPS as their only source of navigation but I was alarmed by this unreliability. I have the lowrance I finder go 2 which I bought for trekking last year and assumed that it would be ok for inshore fishing ?? I have used it twice before with no problems !!

 

What I would like to know is-

 

Is losing a fix like that a common occurance ?

Is the signal interupted by thick fog ? surely that is when its most valuable ??

Would I be better off and would I see an advantage in spending a lot of money on a top of the range nautical handheld GPS ?

 

Thanks in advance for any help and advice

 

That experience is rather worrying and at the same time interesting.

 

Personally (like you) I would not rely on a GPS only, without a compass.

 

I have a Garmin III+ which I have used for cycling, hill walking, forest rambling, car navigation, etc. Never had any problems re loosing the satellites, except in a forest. The GPS antenna needs to be able to see the respective 8 or so satellites in the sky. This is the same in principle to satellite TV reception. You cannot get a TV sat signal without direct line of sight to the single satellite (say Astra 28) which is beaming your chosen programme. Hence the problem in summer when the neighbour's trees grow leaves or just plain grow and block the view of the sky.

 

There is sometimes a problem in very heavy rain - can be at the uplink end (the broadcaster) or the downlink (your satellite receiver) if the weather is really extreme.

 

Now the question of fog is interesting. Clouds are effectively fog - i.e. fine suspension of water droplets and sea fog will be, I think, much thinner in depth than clouds in the sky. GPS can see through clouds - so I find it difficult to see why sea fog should have caused a problem with the GPS satellite fix.

 

I know that my GPS is rather old and there are better chipsets out there (Surf III) which do a better job at eliminating interference. However, your GPS is only one year old, so I would have thought that would be OK.

 

Maybe you could contact Lowrance Tech Support and ask their opinion. Could your GPS unit/antenna have an intermittent fault or poorly performing antenna?

 

Steinbeisser

[Simon Everett]

As it is Lowrance kit I suggest you ring the Lowrance Guru - Iain Henderson on 01506 406290, he will sort you out.

[YakDiver]

I had something similar, riding on my bike the GPS put me in a field 150 yard away and stayed like that for over 2 miles I just put it down to poor reception

[robq]

Thanks guys, been out again today and it has been fine, Think I will still drop an E mail to lowarance though.

[codshead]

Buy a compass and take a recipricol bearing on the way out as back up, it wont be pinpoint accuracy but it'll get you back in the ball park.

[Steinbeisser]

Maybe the GPS is OK and someone is messing with the signals (if that is possible?!)

 

http://www.anglersnet.co.uk/forums/index.php?showforum=26

 

Steinbeisser

[robq]

Maybe the GPS is OK and someone is messing with the signals (if that is possible?!)

 

http://www.anglersnet.co.uk/forums/index.php?showforum=26

 

Steinbeisser

 

Thanks for all the help lads, It did it again on tuesday night and then switched itself off and on several times ! and then refused to be turned off at all ! it seems that water has got into the unit somehow ?? It as supposedly waterproof to ipx7 standards, it has never been immersed and only every had a bit of light splashing so I was a bit dissapointed by this. Anyway I took it back to the retailer this morning and he gave me a full refund. I will be spending a bit more on a decent marine handheld probably with the built in uk admiralty chart and basemap, I would have bought a combined FF/GPS but have only just got a new FF. Does anyone have any of the top of the range handheld GPS units ?

[YakDiver]

It supposedly waterproof to ipx7 standards

I always put my GPS in an aquapac waterproof bag never trust the advert!!!!

As for top of the range I first bought mine in 2001 and cost £400 with all the bits and software it is the Garmin e-map which has maps of land base and not for the sea, but I have plotted down a few buoys and danger marks ect in my area and of course fishing marks, a GPS chart plotter/fish finder looks great, but out of my reach at the moment as I have just bought a new kayak.

Send you GPS back to them and 9 times out of 10 you will get a replacement free of charge I did this with my Garmin FF it was over 18 months old and the plug had corroded and some of the pins were missing took it in two days later went to pick it up it was a brand new one also free of charge

[Nicepix]

Hi all,

 

I had a fairly unpleasant experience on friday last week whilst out fishing, when I set off ( only 300 yards out) visibility was a bit murky but probably around 1/2 a mile. However after an hour or so fishing it was down to 40 yards or so, not a problem as I had my GPS and compass I thought. However at the end of one of my drifts the GPS lost its satellite fix leaving me not knowing my position !! and also gave me an assumed position about a mile from where I knew I was

 

Anyway I trusted my instincts as to where I was certain I actually was and used the compass to find my way back in ( succesfully ). back on the beach the GPS didnt pick up another fix for around half an hour

 

I know that nobody should ever rely on a GPS as their only source of navigation but I was alarmed by this unreliability. I have the lowrance I finder go 2 which I bought for trekking last year and assumed that it would be ok for inshore fishing ?? I have used it twice before with no problems !!

 

What I would like to know is-

 

Is losing a fix like that a common occurance ?

Is the signal interupted by thick fog ? surely that is when its most valuable ??

Would I be better off and would I see an advantage in spending a lot of money on a top of the range nautical handheld GPS ?

 

Thanks in advance for any help and advice

 

I fished the same mark as you on Thursday in similar conditions. No problem with the GPS so I'd be tempted to give it a good work out on land to see whether the unit is faulty before venturing offshore again.