May 27, 2023
Cover Photo: Smith Bay, Prince Edward County, Ontario
As I wake up in the county of Prince Edward, Ontario and look out the windows of our small cabin, my heart soars to see the sun rising over the water with a blue cloudless sky and light winds. WOW! It is going to be a perfect day for shipwreck hunting!
So, how do you locate a shipwreck underwater?
We are used to life with cell phones and google maps, you simply enter an address and away you go as it precisely guides you to your destination.
My boat is equipped with an advanced chart plotter (GPS for on boats) and sidescan sonar unit. Since the wreck was located by the Fabulous Four over two decades ago you would think that we just need to enter the latitude and longitude and it would guide us directly to the wreck.
Reality is completely different and the lake loves to keep her secrets!
Twenty years ago, GPS is not what it is today. Originally built for the military it was transitioning in the late 90’s to civilian use and accordingly the accuracy could vary greatly from region to region based on both satellite coverage and the quality of the GPS device you were using.
Each of our four shipwreck hunters had their own boats with different types of GPS units. Having plotted the coordinates that each of them gave us on a map, we found they were up to 300 meters apart. On land, with this amount of variation it may take a bit of time but you would ultimately find your target. On the water with the ship hidden 40 meters below it can be like searching for a needle in a haystack.
In movies sidescan sonar images always shows the target in beautiful detail. Once again, reality is completely different. Thermocline are changes in water temperature at different depths that can reflect the sonar beams making it look like there is nothing there. Plus when working perfectly there is still an art to reading sidescan imagery. On high resolution passes shipwrecks do show up very clearly but they only reach out a short distance on either side of the boat. Low resolution passes can look further away but lack clarity and detail, hence the art of reading them.
So, our plan is to keep our fins crossed and offer a prayer to the sonar gods for successful search!