Mark consider it done!
Sickb4st4rd; the canal changes direction 4 times in a 24 hour period,you have Buzzards bay(west end) at one end and The Cape Cod bay (east end) at the other,both bodies of water have different high and low tide times,so the current flow will always head in the direction of the lowest level of water.The current flow will move west for the beginning of the ebbing tide,because the east end (cape cod bay) is also ebbing ;the water level will get lower at the east end causing the westward flow to slow until it stops,this is whats refered to as slack tide,this is roughly 1 hour and 45 min. from dead low at the east end,the current flow will now change to an easterly direction until it reaches the end of the ebbing tide (at the east end),it will continue to flow easterly into the flooding tide.Cape cod bay will reach the high flood stage before the west end does (Buzzards Bay),so the same thing happens as in the ebbing tide,because the east end is now higher than the west end the tide will slow to slack tide and reverse direction about 1 hour and 45 min. from high tide ,now it will flow west into the remainder of the flooding tide .Confused?
The simplest way is to look at a tide chart for the canal,for example if low tide is at 6:00 am the tide will change to an east directional flow at 4:15 am ,if high tide is at 12:00 noon at the west end the tide will change to a westerly direction at 10:15 am.