DIY Charting from the tender

[danderer]

This may not be feasible but...

I've got Garmin 76XX equipment on the boat. Also an iPad that receives NMEA0183 and is used for Aquamap (USACE) and Navionics (crowd-sourced SonarChart).

What I'd like to do is be able to use the tender for scouting shallow areas and passages, and then have that data available on the big boat. Something like have a gps/sounder on the tender, survey the desired area with the tender recording depths to an SD card, and then pop the SD card out of the tender and plug it into the big boat.

An alternative I could imagine would be to use Navionics on the iPad to create SonarChart Live recordings, but then the tender would need a way to broadcast 0183 to the iPad, and I'd have to juggle the iPad in the tender and remember to set the depth offset in Navionics depending on which boat it was in and..

I suspect this isn't easily possible but I'll admit to not fully understanding the Garmin world yet so maybe...

 

[Dougcole]

Following this closely, very interesting.


Sounds like it would be a much better solution than my way, which is to line up landmarks on shore and poke an oar down toward the bottom. Lol.

 

[MYTraveler]

Several years ago, Furuno came out with a feature to their NN3D system, which they call PBG -- Personal Bathymetric Generator. It will be a feature to their most current system TZT3, but that has not been released yet. There is also a facility to export and import data from one system to another. It sounds like this would do what you want. For all I know other manufacturers have come up with something similar, though I have not seen it.

 

[Gabe n Em]

I've got a hummingbird in the dinghy with sidescan. I drive in there, recording, and then go home. I have a computer with reefmaster software ($200) that stitches it all together, with a variety of options (mosaic, bottom hardness, depth offsets, etc). It can export in a variety of formats, one being Garmin gpx. I put that on a sd card and plug it into the 1022 on the mother ship.

When I get around to upgrading the dinghy electronics, I'll go all Garmin. Just make sure there are two sd slots on the mother ship. You could just copy over any charted areas using quickdraw

 

[danderer]

When I get around to upgrading the dinghy electronics, I'll go all Garmin. Just make sure there are two sd slots on the mother ship. You could just copy over any charted areas using quickdraw

This is what I think I'm looking for. To clarify"

- Are you saying I can just take the card from the <Garmin to be determined> in the tender and plug it into the 2nd slot on the mothership?
- What is the "copy over.. using quickdraw" process?

Like I say, I don't have Garmin figured out all that well yet.

 

[Lepke]

You need to factor in the tide when establishing soundings. Usually soundings are adjusted to mean lower low water by charting agencies.
I make new or modify charts of some difficult anchorages. I use my tender to chart so I can get the big boat in safely. But I do it the old fashioned way with a sextant turned horizontally and taking angles of landmarks. I think it's more accurate than gps.

 

[MYTraveler]

You need to factor in the tide when establishing soundings.

The furuno PBG system, at least, does auto tide correction. (And it saves both the raw data and the correction factor.)

 

[Portage_Bay]

You need to factor in the tide when establishing soundings. Usually soundings are adjusted to mean lower low water by charting agencies.
I make new or modify charts of some difficult anchorages. I use my tender to chart so I can get the big boat in safely. But I do it the old fashioned way with a sextant turned horizontally and taking angles of landmarks. I think it's more accurate than gps.

I agree there is inaccuracy, but I think it's the charts not the GPS. Charted objects and depths in a local area are accurately placed relative to each other. But the charted area can be a bit displaced on the surface of the earth. Lightly traveled areas with charts based on old surveys can be off enough to cause problems. A real cartographer could step in here and tell us the how and why.

Horizontal sextant angles are incredibly accurate. Another method is to launch the dingy and tour the channel looking for safe water. Then run it again with a hand held GPS zig zagging in crossing over your intended course. Drop a mark as you hit the deep spots. Back on the big boat stitch the dots together to make your entrance course. If you need the extra confidence run your newly plotted entrance channel in your dingy to ensure you haven't made a mistake.

In areas with significant tidal ranges if you make your dingy survey at low tide and bring the big boat in at high tide it's easy peasy.

How you get the course from your hand held to your big boat's nav system is system dependent. I use a Garmin hand held and either Coastal Explorer or OpenCPN so it's a simple export / import of a GPX file. Once you are comfortable with the technique a world of anchorages ignored by everyone else opens up to you.

If you're squeaking into really tight spots you'll need to know where your GPS antenna is relative to your bow and stern.

 

[Gabe n Em]

Yes, sorry. To clarify: quickdraw is garmin's charting feature. It takes fish finder and gps inputs and makes a chart on the fly. It's not as accurate as I would like, but for the ease of use, I'm planning to go that way.

Our Garmin 1022 mfds have two sd card slots. You can copy from one to the other, right in the mfd. Or just build your charts and waypoints from both at the same time.

Cheers

Gabe

This is what I think I'm looking for. To clarify"

- Are you saying I can just take the card from the <Garmin to be determined> in the tender and plug it into the 2nd slot on the mothership?
- What is the "copy over.. using quickdraw" process?

Like I say, I don't have Garmin figured out all that well yet.

 

[cafesport]

Been doing our own bottom charts via dinghy and kayak for several years. There is now technology available to automate this. Using an iPad connected via wireless to a device from digital yachts allows you to do real time tide adjusted bottom charts using apps from navionics, aqua map or tz iboat. How you get that to your primary mfd depends on which app you use. Go to your app’s manual for specifics on how to do this.

 

[bowball]

I'm late to this, but considering the same thing now for my tender, with the main boat using furuno tz3 mfd's.

I would like to be able to map tide adjusted the bottoms with the tender and have that transfer to my tz3's.

I thought about the side scan feature that Furuno has with their PBG 3d feature ... but it was hard to convince myself of the expense for this use. I wish Furuno would create a system though where we crowdsource and share this data, to create far more accurate maps (as long as everyone is using the SC20 satellite gps system).

Any insights here for me? Using an iPad on the tender running TZ iBoat app somehow? If the iPad is visible in the sunlight. I would prefer something more permanently mounted.