Originally Posted by billows
Can anyone explain, low tide heights are kinda important as a lot of ribbers with busted props will testify
Well, tides are estimated and v. dependant on Pressure and Wind direction/speed, so I'd be wary of using 0.85m as a prop guard. The variation may be down to the different platforms using different algorithms* to calculate tidal heights, different datum points and possibly (more likely) in this case, different times, i.e. summer/winter - have you checked? Also, your plotter software may need updated? For the craic, compare tidal peaks on printed charts to various electronic sources - they will likely all vary a tad.
*The prediction of Tidal data made by viewing the movements of seaweed...