I have it in my Lowrance on the boat, it is however from 3 yrs ago and the lake level when it was done was at 1836 I believe anyway

Two parts to that answer and I cannot remember which end of the lake was which but one was at 1814 and the other at 1817.

And the iPhone stuff will be tricky.

Everyone likes to talk "one foot contours" or "three foot contours".  Truth is, your GPS decides the "FINAL" accuracy.

I don't know if iPhone has a standalone GPS receiver in it.  If it does, I suspect it is set to be a very high sensitive receiver.  You have high sensitive receivers in most of the Tom Toms, Garmins, Lowrances, etc like the vehicle units.  I imagine the phones are the same.  This allows you to keep a lock no matter the conditions (buildings, canopy, amount of satellites available, etc).

This works for the purpose but when we talk accuracy you need to remember even if surveyed in at 1 foot contours if you have a high sensitive GPS receiver you could expect 30 feet and beyond inaccuracy.  Maybe not a huge issue for many applications but if you get mad you are standing on 10 feet but find out you are in 20 feet it could be because your GPS is placing you in the wrong spot.

Boat units are more accurate.

And yeah, it is really a bunch of fun doing the math on 1814 versus 1839 of which we are sitting at now.  And if you are in beyond where 1814 would be you have no contours.

Tim Sandstrom Said:
Two parts to that answer and I cannot remember which end of the lake was which but one was at 1814 and the other at 1817.

Tim, I thought it was done at 1824 give or take a couple feet during the process.

pigsticker Said:

Tim Sandstrom Said:
Two parts to that answer and I cannot remember which end of the lake was which but one was at 1814 and the other at 1817.

Tim, I thought it was done at 1824 give or take a couple feet during the process.

I'm not sure what the level was when it was mapped but most of my fishing last year there was no contours.... 

Thanksgiving day I was on the lake and fishing around 30 feet.  My navionics map varied spot to spot showing different depth contours.  One spot was 10 feet on the map  the next was 15.  I've noticed this many times before.  So i don't think the mapping is real consistent.  But it does usually show most of the important features.

Sure would be nice to get them back again to map it at full pool... 

It was between 1812 and 1817 depending on the area of the lake they were at.  I think I always used 1814 to kind of meet in the middle.

I'd have to get on my home computer to track down the email but I Googled FBO talk forums and everything posted references that 1812 to 1817 number and specifically 1814.

And walleyes,

Tell me about it.  The lake was sitting at 1858 ish or whatever it was.  I'd have to go look again but it was a golden opportunity.  Must not be a lot of chips sold or something because if Lakemaster was smart they would have came in and did the lake and completely stole all of the ND customers from Navionics.

But I still don't understand why in the heck LIDAR wasn't shot for the lake when it was at it's rock bottom of 1804.  That was the dumbest move of all.  The Corp could have used that for very valuable silt studies, etc.

Pigsticker,

Here's one of your posts from one of the forums I googled:

Re: Navionics for sakakawea
pigsticker Joined: 05/04/2005 Location: ND	navionics is based on 1817-1818 for Sakakawea. I spoke a lot with them when they were running the lake and finalizing the chip. They cannot integrate data for some reason so the only time you are going to have a new elevation of higer lake levels is if they bring the boats back out and run the lake again. I was quite surprised to hear this.  Oh, and don't waste your money on the new chip. You will gain no information for our area. I dealt with this quite a bit when selling them and a lot of people didn't quite believe what I was telling them, but hey, if they insisted to spend the extra $50 I wasn't going to argue. Hope that helps.
	HOLY!....GET THE NET!!!

Tim Sandstrom Said:
Pigsticker,

Here's one of your posts from one of the forums I googled:

Re: Navionics for sakakawea
pigsticker Joined: 05/04/2005 Location: ND	navionics is based on 1817-1818 for Sakakawea. I spoke a lot with them when they were running the lake and finalizing the chip. They cannot integrate data for some reason so the only time you are going to have a new elevation of higer lake levels is if they bring the boats back out and run the lake again. I was quite surprised to hear this.  Oh, and don't waste your money on the new chip. You will gain no information for our area. I dealt with this quite a bit when selling them and a lot of people didn't quite believe what I was telling them, but hey, if they insisted to spend the extra $50 I wasn't going to argue. Hope that helps.
	HOLY!....GET THE NET!!!

Wow! I guess my memory is a bit foggy. I called navionics when I read this thread to find out what the contours were based off and they obviously have horrible record keeping because they indicated 560 meters (1836.8 ft) which was very wrong. If my foggy memory is right we dropped even lower the next year and we never reached that 1837 level again until just a few years ago. I asked them to verify the year the data was entered and they couldnt even produce that. I said so essentially you don't even know the accurate level of what your contours are based off of and he replied: it says here 560 meters. Oh well, at least I tried.

Thanks for digging that up Tim.

A little off topic but i was wondering if anyone has one of the older hot maps north chips for my lowrance ifinder h20.  I usually fish ashtabula and that lake does not change much so i dont need the new expensive one.  I had the hot maps north in my other ifiinder but it got stolen from me last year so i had to get another one but now i need another chip.  if anyone upgraded theirs and has their old one and wants to get rid of it let me know.  Thanks guys.

icefreak Said:
A little off topic but i was wondering if anyone has one of the older hot maps north chips for my lowrance ifinder h20.  I usually fish ashtabula and that lake does not change much so i dont need the new expensive one.  I had the hot maps north in my other ifiinder but it got stolen from me last year so i had to get another one but now i need another chip.  if anyone upgraded theirs and has their old one and wants to get rid of it let me know.  Thanks guys.

icefreak,

Sorry for the late response, but one option would be to change to the NDTRAX chip for Lowrance. This will have 175+ of the main lakes in ND including Ashtabula, plus it will have public lands, PLOTS, roads, streams, section lines and more. NDTRAX is only $80. Just a thought.

korey,
     Thanks for the info.  since i last posted i have done some looking and the NDtrax chip is pretty nice.  I think i am going to go ahead and get that one.  Thanks for the info.