Cape Cod Canal Tides

Cape Cod Canal Tides

Ebb and flow…such a simple concept, but not in the Cape Cod Canal!

While planning a delivery this weekend, I had to grapple with the complicated nature of the famously-swift water movement through the Cape Cod Canal.  Although I grew up not far from there, I never appreciated all of the complexities until now.

The Canal is more difficult to understand than most waterways because its movement is not entirely contingent on the tides around it.  For example, on this particular delivery day, slack tide in Sandwich at the eastern entrance (Cape Cod Bay side) is at 6:45AM; however, slack tide within the canal is at 5AM.  How can this be?

Steve in Mass from Stripersonline.com explained this phenomenon well:

This is all because the water levels (high and low tide) on the west end (Buzzards Bay) occur about 2.5 - 3 hours before the same high or low water occurs on the east end (Cape Cod Bay). In addition, the tidal difference from high to low in Buzzards Bay is only about 4.5-6 feet, whereas the tidal difference between high and low in Cape Cod Bay can be anywhere frmo about 8 feet to as much as 12 feet plus (depending on the moon cycle).

So, we get a crazy current cycle that takes a special chart to examine and plan for.  Ryan Collins also had a great article on understanding the Canal.

Most important to remember is the general direction of flow: east-west for an outgoing tide, west-east for an incoming tide.  In addition, know that in the brutal current flow, which can easily exceed 6 Knots, your vessel must be able to transit the Canal in a specific amount of time.  OffshoreBlue.com notes:

All vessels, including pleasure vessels, must be able to transit the land cut portion of the canal, between the Cape Cod Canal Control Station in Buzzards Bay and the East Mooring Basin in Sandwich (approximately 5.9 NM) within 2 hours and 30 minutes against a 6 knot foul current.

That means that a 7-knot sailboat or an 8-knot trawler may not transit the Canal during adverse current conditions (against the current).  Therefore, planning your transit ahead of time is a must!

There is no limit to the learning curve when it comes to boating…in this case, the Cape Cod Canal is its own mini waterway system, and it pays (in time, and in fuel) to know the right way to make the journey.