The low, low tide is usually negative. Like -1.0 or something like that. Mean low water is 0.0. That is what nautical charts depths are adjusted to. So if its a -1.0 it will be 1 foot lower than the chart says. That is usually only on the low , low. The higher low will usually be very close to the mean low water= 0.0 or maybe higher. There is a higher low and a lower low. It all depends on where the moon and sun are. The moon effects the tides more, but the sun does also. About once every 6 weeks, there is what is called Spring tides, it is when the sun and moon are in the same phase for about 3 days, and tides are much more pronounced, especially in the winter with strong winds blowing offshore or onshore. Wind effects it also, and it can be a strong and lower or higher tide than normal. When there is a very high , higher low, that is called a 2 tide day, as it seems that there is only one high and one low. You do want to get out there on really negative tides, and especially if it has strong offshore winds. That makes it very low.
