Mapping depths using GPS/depthsounder

[troppo]

Previously, I have added depth data to my own paper charts of the basically unsurveyed tidal Fitzroy River, Central Qld, which I often travelled up and down, using a Garmin GPSMAP 750s and Garmin MapSource software on my PC. The Garmin saved the depth data and position which I then converted to chart datum and added to my paper chart. It meant I ended up finding where the channels were and could calculate when I could safely go through shallows.

Now I am seeing that various companies offer GPS/depthsounder units with the ability to create maps with contour lines. Ones I have read about include Garmin Quickdraw, Navionics Sonar Charts and Hummingbird Auto charts.

Have you used any of the units to create your own charts? What was your experience? Any thoughts?

[mausgras]

I'd be interested in people's replies as well. I mostly cruise in shallow coastal waters and the charts I use don't seem to be all that great.

[epiic]

I was going to order this until I decided Bahamas is so damn crystal clear, I really don't need it yet.

It sure would have been nice to have looking for anchorages along the ICW.

https://www.amazon.com/gp/product/B0...A1GIKH3L785S8V

[mausgras]

I use Navionics on my chartplotter and in most locations the data is great. But then there are spots that are way off the official charts. They have a real time updating system called "Sonarcharts".
I have often wondered how good this and how it works. Do they just update the official chart or completely redraw a new one. In coastal waters near rivers with shifting bottoms this would be quite useful to know.

[troppo]

Towards the mouth of the Fitzroy River, Qld, the changes to channels over the years is substantial. One channel, which is still on the charts as being recommended, has a depth according to my charting of 0.7 metres in spots. With 4 metre tides, keel boats still go through. However, it is narrow in places with a rocky point one needs to go around. Not all do safely.

An alternative, which the Coast Guard told me about, shows up on the charts only as shallow emerging mudbank. But it now has a channel of 1.7 metres which makes it way better than any other channel.

Even though the Coast Guard told me about the alternative channel, I still spent hours in a dinghy with GPS/sounder working out where it was and the depths. Certainly gives me confidence when going through the area, especially on a falling tide.

These new electronic gadgets able to quickly do the sonar mapping should be perfect for places like I go over but I don't think too many people have the need.

[Roy M]

I purchased a transducer for my B&G NSS9 display, which I have mounted on my RIB scout boat. About nine months ago I did a survey of the waters around my yacht club to help us with planning for dredging some silt that accumulates. The software is available from Insight Genesis, through Navico. I have the professional version, costing about $100. A free version is also available. The chart developed is incredible. The examples shown here are the track of my RIB as I cruised around each of the docks and fingers over a three hour interval. Then, I sent the scan to Insight Genesis and the processed chart was ready a short time later. On my laptop I can display it at several different contour levels, show vegetation and bottom qualities. It's a hell of a program and system. In addition, I added a 3D Structure Scan transducer for fish finding applications. I love this unit as well.

[mausgras]

It sounds like you should talk to Navionics. I met their Aussie rep at the Sydney boat show. He was very helpful and I'm sure would answer any questions you have.

[troppo]

Roy M, that map looks great. I can see how it would be useful to see where the silt builds up. Certainly useful technology.

[Roy M]

The Simrad rep introduced me to this product. The Santa Cruz, California harbor entrance silts up regularly. They have been using this product on a daily basis, and upload the results to their website. Here is today's chart showing the silting at this date. They send a guy out with a pontoon boat, equipped with the sounder. The maintenance guy (basically, a boat driver who can follow directions for turning on the sounder, removing the chip and uploading it), needs only a short period of time to record all the data. You can see the results. There are a lot of folks who could gain a great deal of information using tools like this. Here's the link: https://www.santacruzharbor.org/docu...veyResults.pdf