Bottom contour mapping via a dinghy

[Paul L]

Originally Posted by Lepke

I like to anchor in remote places in Alaska and Canada. Some places haven't had new surveys in 100 years. And some places had the bottom raise after the 1964 earthquake. I use a spare Furuno depth sounder in a small boat to sound out entrances and prospective anchorages before I risk the big, wood boat. The sounder along with a gps plugin and my laptop adds the new depth after I've corrected for the tide state. Enough passes and I've found all the rocks and shallow spots. Sometimes I can find a natural range and in a few places I've made rock pile ranges so I can visually stay in safe water and go back year after year.
After that, it's quiet and I have nobody bothering me.

What program are you using to save and plot the data?

[Jammer]

Originally Posted by Dave_S

I assume Navionics will want to see repeated information from multiple sources to use the information.

Navionics has published depths for upper and lower Lyman Lakes as a result of soundings I took one day:


https://webapp.navionics.com/#boatin...y=%7DaknGnqpwP


They also have soundings for parts of the Cannon River, and have added the canoe access on it based on information I have provided. I do not believe they have corroborating data from anyone else, however, in this case, I have made multiple tracks over visits on various days:


https://webapp.navionics.com/#boatin...y=ahinG%7ClswP


They also have updated the soundings for Holland Lake, including the "Navionics" data as well as the "Sonarchart" data, based on surveys I performed. I do not believe anyone else has surveyed the lake, because it is only accessible to hand-carried boats.


https://webapp.navionics.com/#boatin...y=urjpGb%7CnwP


Based on this, I believe it is their policy to share any sonar data they receive that meets their basic quality guidelines, even if they only receive that data from a single subscriber.

[Dave_S]

[QUOTE=Dave_S;2812799] You can chose to share these maps with Navionics or not.
[QUOTE]

This has changed, if you chose not to share it turns off the feature so you can't use it. That's crap

[tomlisasail]

We just bought a handheld depthfinder from West Marine for about $70. We haven't used it yet and I don't know the model because we just took it to the boat. We have kayaks and our plan is to have my wife mark our position on our hand held gps while I get the depth. Obviously we are not that advance technologically, but we will use this technique and test it in soft bottom areas while we are still in range of Us towboat.

[geoffschultz]

One interesting this is that many countries in Central America are listed as being Economic Exclusion Zones, and they prohibit the sharing of mapping data.


I went out and purchased a Vexilar SP300 and I'll use the Navionics app to attach to it.


One question that I have is if I collect the data on my iPhone, will I be able to sync the Navionics chart on my sailboat's B&G Zeus 3 to display the data?