Topic: New Member to SideImaging Hi :) Questions from a first time user of Autochart

[buzzingrub]

I'm an IT guy, and Autochart is quite demanding to operate, so I have been mapping my local lake the Occoquan Reservoir in Fairfax VA. This  doesn't appear to be a Lakemaster mapped lake, and the shoreline is all straight lines with no detail. So when I track the lake I find it doesn't fit well into the outline of the lake and there appears to be overlapping shoreline segments and the mapping process seem to get confused due to the conflicting shorelines. I've been trying to draw it from MapQuest and I think that is looking a lot better,  So my question is how to best tackle this and what device would best achieve the recording as I have a 899, 859 and a 360 (which does SI and DI along with the 360 image much to my surprise) they are all networked using an Ethernet hub. When I am recording I notice the sonar image shows some kind of interference like a heart beat, which only occurs when it is recording, as if it can't write to the information fast enough or something, and sometimes it freezes for a second or two.

Thx in advance Buzzingrub (Peter) 

[buzzingrub]

OK no takers, so I'll start by answering some of my own questions that I have read from other post on the board.

For the shoreline I'm going to load MapQuest and draw a line round all the reservoir I'm likely to map and then using the General settings I'm going to tell autochart to use it as opposed to the lakemaster shoreline. I hop this translate to the map created in the AC folder on the Zero Line SD and displays on my 899.

As for recording I have bought a super fast SD card to see if the heart beat freezing eases up.

I'm not sure if the 360 or the 899 would be best to use for the recording data, maybe someone can comment on this.

[CamoHunter]

Sounds like you've got a good start on getting a handle of things. 

As for which sonar to use, here's my suggestion.

I would use the transom mounted transducer, and have an external gps mounted close to that transducer.  You can record on either your 859 or 899, just make sure to select that transom transducer and gps receiver.  The reason I recommend the transom transducer, is because I think it would be more stable in the water than the 360 transducer, which would be deployed and rock back and forth more in the water.

[Humminbird_Greg]

Welcome to the Humminbird Side imaging Forums Peter.

Since you bought the AutoChart Pro version software, I am assuming (uh-oh...) that you want to be able to make Si mosaics and so should record with the 899 unit.  I would use a transom mounted transducer like CamoHunter suggested.

[buzzingrub]

Thx guys, the 360 actually does a a$$ job with regard to the side scan and the down scan, and my external GPS which came with the 360 is at the front of the boat. I just finished another session and once again I notice the sonar will stop scrolling while the DI does not , and the depth seems to be fine. Working the software is a challenge as there are so many parameters, many of which I do not know what they do or weather they effect the created map or are just effective while running on the PC. 

[tambrose76]

Brings up my un-obvious question... since my External GPS Humm antenna is located directly, exactly 9ft ahead of my transducer, should I be setting some sort of offset on my 898, and will there always (then) be that 9ft error in the direction of travel whilst mapping?  Does AutoChart have a means of zeroing out those sets of errors, say by comparing a waypoint [boat landing] to google earth zoom waypoint data?

[CamoHunter]

Correct.  With a GPS antenna 9ft away from a transducer, you're automatically introducing 9ft + of mapping error right off the bat.  If you're wanting as accurate of a map as possible, you'll want an external GPS antenna mounted as closely as practical to your source for the depth reading (transducer). 
There might be a GPS offset, but as you mentioned, it would depend on which direction you're driving the boat on the direction your gps reading is from your transducer.  But, if you're collecting depth readings while fishing, or drifting for walleyes for instance, direction of travel wouldn't be correct even. 
Therefore, best solution would be a gps receiver close to the transducer, or to accept the fact your map will still be good, but not perfect.