Been researching an upgrade to my Deeper Chirp2, but I'm getting nowhere. Everything pertaining to autonomous boat scanning brings up cagy questions for 2016 at best lol! So I'll lay it out, no cagy questions : ) I've got a Pixhawk controlled bathy boat with a Deeper Chirp 2 sonar (don't laugh) recording to a android tablet via wifi. The tablet is being location GPS spoofed with RTK corrected. GPS corrections come in at 20Hz while the Chirp scans at 15Hz. Problem is while it creates pretty data on the Android device, it only outputs depth in a csv file format. So for a lot of detail requires lots of tracks. From some of the old posts here there was mention of post processing gnss data. I usually scan from the air with lidar, PPK gnss with a KVH 1750 IMU. Even then you still need to post process trajectory and correct lidar points between each flight path. For bathymetry I wouldn't expect this level of accuracy, but I'l like more detailed data from say like a side scan sonar. My research into sonar head units/tranducers is going nowhere. What's with all these crazy marketing terms? Super wide, wide ultra hd, crazy super with super super-duper hd... Ok, I'm making that up. What's an awesome unit to use with Reefmater that's got a compact head unit (relatively)? And how much can Reefmast process this data in terms up update rates and gnss data beyond what was discussed back in 2016 (1m)? I'm under the impression the software takes a slice of the side scan sonar and pieces it togeth like lidar flight lines.

BTW, I found the software from a Ardupilot boat discussion group. The member wanted to do bathymetry but thought the $200 was a lot of money. That's crazy, anything in the lidar world of post processing you can add one of two decimals to that. Seems like really good value for $200!

Hi - sorry, missed this post earlier! Nice looking boat.
One thing I should say straight away is that sidescan does not provide any extra depth information over traditional 2D sonar - you still get depth below the boat only. Although there are now some consumer technologies that can - in theory - give you multi-beam type performance with depths recorded out to the sides (e.g. Lowrance SS3D), we don't yet support them. What RM can do, with the sidescan mosaic module, is piece together sonar imagery that extends to the sides of the boats - just be aware that won't improve any bathymetric maps.
As for a light-weigth head unit, you just go with the smallest screen size in whatever range you are looking at, since this won't affect the data that is recorded. I'm not super up to date on the latest units, so perhaps others will chime in, but anything by Lowrance/Simrad or Humminbird should work well.