Since most of us can appreciate a fair current push to help us along our way, how do we determine the best times to make the Chesapeake and Delaware Canal passage?
For those of you that are just looking for the numbers, we will get them out of the way now:
We will be using the NOAA Tidal Current Tables; you must correct for DST when necessary. For those that prefer you can use Eldridge. Simply look up the C & D canal in "Table #1" and extract the time of "Slack Water Flood" (eastbound vessels) or "Slack Water Ebb" (westbound vessels) at the Chesapeake and Delaware Canal reference station, in this case Chesapeake City, MD. From "Table #2", extract the time corrections for the proper substation, and apply this correction to determine the correct time for slack water.
For our example we will use the NOAA Current Tables and compute the times for the first favorable current of the day on January 1st.
|C & D Canal Fair Current Timing|
|Eastbound Passage||Corrections||Slack Water Flood Begins|
|Chesapeake City - Reference Station (Table #1)||0052|
|"Back Creek" (Table #2 corrections)||-0003|
|Slack Water Flood Begins @ "Back Creek"||0049|
In the table above we are transiting the C & D Canal eastbound from the Upper Chesapeake to the Delaware River. So we need to find out what time we should be at the western entrance of the canal to catch a fair current. We know that the current floods eastbound in the C & D so we will be looking for the first flood current of the day.
For a westbound passage we simply repeat the process using "Slack Water Ebb," since the current ebbs to the west, and use the sub-station at the eastern entrance to the canal, "Reedy Point". (See below)
|C & D Canal Fair Current Timing|
|Westbound Passage||Corrections||Slack Water Ebb Begins|
|Chesapeake City - Reference Station ( Table #1)||0647|
|"Reedy Point Tower" (Table #2 corrections)||-0007|
|Slack Water Ebb Begins @ "Reedy Point Tower"||0640|
On average, a 7 knot vessel will have a about a 3½ hour window from the time of slack water to make the passage and still have a fair current the length of the canal. A higher speed vessel will have an even larger window.
There are 2 ways to approach this problem the "Right Way" and the "Other Way."
Beginning at the entrance to the canal at a specific time, you must first compute the actual velocity of the current for that time.
The "right way" will provide you with improved accuracy, but the 2 things to consider here are:
Hell, you might very well be through the canal by the time you redo all the calculations.
It may be just me, but I am seriously into "the other way!"
In an effort to keep it simple we have done some of the calculations for you (to 1 decimal place). Using the NOAA Tidal Current Tables #2 we extract the average maximum current velocity for the Reference Station as well as all of the Sub-Stations located in the C & D Canal and then take the average.
|C&D Canal Average Maximum Current Velocities|
|Current Station||Ebb Current Avg. Maximum||Flood Current Avg. Maximum|
|Back Creek||1.4 knots||1.2 knots|
|Chesapeake City (Ref. Sta.)||1.9 knots||2.1 knots|
|Chesapeake City Bridge||1.4 knots||2.0 knots|
|Conrail Bridge||1.3 knots||1.9 knots|
|St. Georges Bridge||1.3 knots||1.7 knots|
|Reedy Point Bridge*||2.1 knots||2.6 knots|
|Reedy Point Tower||1.4 knots||1.2 knots|
|Canal Average||Ebb Current 1.5 knots||Flood Current 1.9 knots|
|*Reported by Coast Pilot #3 Chapter 7|
Keep in mind that this is the maximum average current speed, if you are of a more conservative nature you may want to modify this number and use that result for your calculations.
With the known distance of the C & D Canal (15.3 NM), the average current velocity, and our intended cruising speed, we can now calculate the time required to transit.At 10 knots cruising speed (± the average current velocity) will give you your estimated SOG. Then dividing the distance by your SOG will tell you how long it will take to make the passage through the C & D.
So if we are westbound facing a foul current (floods east) for instance, simply take your cruising speed (10 knots) and subtract the average current speed (1.9 knots) giving you a SOG of 8.1 knots. Dividing the distance (15.3 NM) by this SOG will result in the time required to pass through the C & D Canal; about 1 hour and 53 minutes. If you waited for a fair current the same passage would only require 1 hour 19 minutes saving you 34 minutes of traveling time. A 7 knot boat would save almost 1¼ hours.
For those that have stuck around this far and have read this whole thing, you deserve something for your perseverance. So here is an extra we hope you will find useful.
We have talked about the timing to get through the canal with a fair current. The problem is that very few people transit the C & D Canal just to get to the other end. Most seem to have some other destination in mind. Don't get me wrong, I do not mean to imply that oil refineries, nuclear power plants, and spoil areas aren’t visually appealing, it just seems to me that most cruisers have something else in mind.
For an eastbound 7 knot vessel bound north on the Delaware River you will want to enter the C & D canal at Back Creek about 1 hour and 16 minutes (±10 minutes) after slack water flood begins at Chesapeake City. This will provide you with a fair current thru the canal and put you in the shipping channel of the Delaware River just as Slack water flood begins off of Reedy point. This should give you about 6 hours of fair current inbound on the Delaware River.
Regretfully, there is no grand solution if you are southbound for the Delaware Capes or Cape May with a low powered vessel. You will have to decide whether to battle a foul current in the C & D or fight the fight when you are outbound the Delaware. The obvious choice, at least to me, would be to take advantage of the 1 to 2 knot push in the Upper Delaware for the trip to the Capes. Even so, a 7 knot boat will likely run out of the fair current in the vicinity of Miah Maull Light. At 15 knots however, you should be able to make the entire transit to the capes with a fair current. To make best use of this, a 7 knot vessel will want to enter the C & D eastbound approximately 37 minutes after slack water ebb begins at Chesapeake City or 2 hours and 56 minutes before slack water ebb begins in the shipping channel off of Reedy Point.
Vessels westbound for Baltimore should enter the C & D Canal approximately 7 Minutes before slack water ebb begins at Chesapeake City. A 10 knot boat will typically carry a fair current all the way to Baltimore while a 7 knot vessel will likely lose the fair current in the vicinity of Pooles Island.