Anyone have any experience of using a home made inshore survey set up? I'm nearly there having found an active transducer which will communicate with my Allegro CX data collector and Carlson Survce. I'm not aiming to compete with the bigger hydrographic survey outfits but lots of coastal jobs require a basic inshore survey in shallow water. The attractions are freedom from tide gauge and water level calcs and position accuracy at the antenna at least. I've fitted an outrigger for stability so hopefully no need to do a 'First Nation rotation'!
Pictures man, gotta have pictures!!! Sounds like a cool setup.
We began doing the same thing back at another company; at the time we didn't have a sounder that would export data to a collector, but we were building a setup based on that premise.
The thing that was most important was determining the reference to use from the transducer - sort of like knowing the phase center on a GPS antenna for the purpose of determining HI. After that, we mounted a staff directly over the transducer with a known height, and it was then a simple calc to arrive at a "finished" HR.
I doubt you'd need to worry too much about temperature, pressure and salinity for most of your work, but it could be a factor in soundings over 100 feet or so; sort of like ppm corrections for an instrument shooting distances in the tens of thousands of feet.
For the construction itself, we mounted the transducer on a piece of 1x12 which also had a mount for the rod - I can't remember how we mounted the rod to the board but I remember it looked like a mini umbrella stand. We clamped the board to the hull, and also had a clamp that held the rod to the gunwale, which in turn helped stabilize the whole setup. We always clamped at the stern, that being the most stable location of our particular vessel.
I too would like to see pictures, and good luck!
FYI:
POB April 2011
http://www.pobonline.com/Articles/Article_Rotation/BNP_GUID_9-5-2006_A_10000000000001020803
We just did a hydro survey using a kayak and the HydroLite system. It was for a pipe line crossing in a river. We use our Trimble R8 with the HydroLite. We just used a 2x4 and strapped it to the hull of the kayak in front of the cockpit. We also had an electric trolling motor on the back of the kayak mounted the same as the transducer. It worked out pretty good. I ended up paddling the sections across the river since the current was too strong for the trolling motor to handle. Our set up wasn't as involved as the POB article shows, but it did the trick.
Here is a picture of Mr Lubic as mentioned:
Don't forget to check with your insurance company if you're new to water work. Years ago the firm I was working for looked into doing some very light hydro jobs, and their insurance agent said as soon as an employee sets foot in a boat the company isn't covered for general liability or equipment loss without an upgrade in coverage (and premium).