Hi hoghunter, thanks for coming back on this and apologies for the delay in replying.
I'm looking at tide tables, i.e. UTC or local times (AST), of high and low tide in St Georges Grenada
using two sources, the Navionics iPad
app and an on-line tide table on Windfinder. I appreciate that the tidal range is only about 30cm and therefore inconsequential in its own right, but the tidal streams change direction in sympathy with the tide times and the cross track streams are significant over an open water
passage and I would like to know what the tidal stream is doing.
My preferred ready access source for tide and tidal stream data is the Navionics package on my iPad
, however, when comparing the high/low tide time data from Navionics and that published on Windfinder, which I assume comes from NOAA or local sources, there are discrepancies of more than an hour in some cases and the times never agree although heights are close. Navionics times are UTC and local sources AST (=UTC -4) and I have allowed for the difference. Interestingly, sunrise and sunset times are identical. Incidentally, I've checked several on-line sources and they all agree although their prime source is probably the same and they all could be wrong
As things stand there's no way I would be sure which is correct although I'm inclined to believe the Windfinder data but won't trust either until I've sorted this out.
I probably need to contact Navionics but I'm interested to see if anyone on here has had a similar experience or can throw some light on the problem.