Most of the data we have collected so far has been for coastal waters, where this isn't an issue. However I agree that in deeper waters this can be an issue, as well as the waters being too deep for the sounder and so returning a value of 0 or 999 or whatever the sounder manufacturer has programmed in. You can see this if you look at the online data for a boat that went from Malaysia
to the Gulf, where the depth sounder
read 0 for much of the passage
One of the things on the to do list is to be able to filter out these values, probably by creating a global 50m set of contours and looking for rogue values on the deep side of that, but we need to get more data from boats going off the continental shelf to warrant the effort and to see the variations in depth sounder
outputs first. With the data processing framework we have, we can plug
in a module to do this, and it will then trigger recalculation of the affected data points automatically.
By the way, I forgot to mention in the original post that we can handle old data as well as new, we just might have to upload some older tide predictions before the old data is processed.