We went up the Essequibo River almost as far as Bartica last Decemer. The BA charts are massively out of date, as are all electronic charts we were able to find. The best resource we found was the Chris Doyle Cruising Guide - his
GPS waypoints and
advice were good as far as Eddie Grant's Island, but there had been some shifting of bars north of that point which ended up with us badly aground for a few days.
The paper charts and digital charts are useful for giving you a (VERY) rough idea of the edges of the river and the islands and landmarks, but the depths and sandbar locations are all wrong. We found that the river banks had also shifted by up to .2nm from the charted positions. Also note that the BA paper charts are NOT WGS 84, you will need to apply a correction to them to be able to plot from
GPS.
We could not find a published tide table online that matched our observed tides on the river, at either Parika or Bartica.
Go read the digital updates on his website as well, we wrote a fairly detailed summary of our info from last December there. If you are going in a relatively
shallow draft boat (< 8 feet) shouldn't be too hard, just only move on the flood tide so if you do hit you can just wait until you float off. We had an 11'
draft and struggled. That being said, there is a channel (un-buoyed) that carries at least 13' at HW past Bartica that is used by small coasters and barges, so another option for deeper
draft vessels would be to wait for one of these to pass (seemed to be at least every other day) and then follow one up or down river, taking waypoints as you go.
Guyana was pretty awesome though - really wish we'd had shallower draft and more time to explore - super friendly people and beautiful country.