Departure Wx- Chesapeake to Maine

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
“Difficult to see. Always in motion is the future.” - Yoda
I'm using Predict Wind and Sailflow.  Of course it's too early to trust a forecast but I'm ever watchful.

The forecast yesterday indicated that departing on Friday would give me the smoothest trip (even if it means motoring) down the Delaware Bay. Now it appears that a Saturday departure (my original plan) will be better. It could change a dozen more times between now and then.

The bottom line is: It's about 65-70 miles from Chesapeake City to Cape May, NJ.  I need to depart Chesapeake City at slack flood for a west-to-east transit of the canal. That's around 11am on Saturday or 12:42 pm on Sunday.  I'm looking at 10-12 hours of transit time to Cape May.

There is a low pressure system passing to the south on Fri/Sat/Sun that is causing lots of dynamism.

 

TryGuy

New member
46
35
NJ
Take a look at the tides for Delaware bay rather than the canal. You really want to start down the bay punching the tail end of an incoming tide which will gradually turn fair and help pull you down the bay. Could take hours off your travel time.

 

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
Take a look at the tides for Delaware bay rather than the canal. You really want to start down the bay punching the tail end of an incoming tide which will gradually turn fair and help pull you down the bay. Could take hours off your travel time.
So basically, depart earlier?  I'd prefer that, actually. Waiting until nearly noon to get underway for a 12 hour leg does not excite me.

 

portofdc

New member
2
2
Atlantic
I built a route in Expedition running 66.5 NM from Chesapeake City to the Delaware Bay Entrance. Assumptions: motor continuously at 6 knots through the water, no affects of wind, Delaware Bay currents applied, and route is along main channel.

I ran about 20 optimization runs and found that the minimum time to run south from C City corresponds with departing at C City at LOW tide at Chesapeake City. The maximum time corresponds with departing C City at HIGH tide (opposite of what is said in the Waterway Guide). Runs starting before or after high and low tides have run times that fall in between the two runs starting at high/low tide.

 

portofdc

New member
2
2
Atlantic
Min and max results

Depart High tide Route 66.6 NM Time 11h 47m 50s Avg Speed 5.64kt Finish
Depart Low tide Route 66.6 NM Time 10h 06m 07s Avg Speed 6.59kt Finish

 

Zonker

Super Anarchist
9,145
5,052
Canada
If you are using predict wind, compare the GFS and ECWMF models. Are they in agreement? If so then you can start believing the forecast. 

Keep watching the forecasted period as it gets closer, about 2x/day. Are predicted conditions changing much? i.e. are the models not really reflecting reality because the input conditions keep drifting. 

 

T sailor

Member
429
93
Chesapeake
The GFS and Euro have relevence once you are outside Cape May and in the Ocean.  I would not put too much stock in it for Bay conditions. Too many land affects that don’t get picked up on the Global models.    They are good at picking up large scale weather but pretty bad and localized wind on the Chesapeake and Delaware.  For this route I would look at the 3km NAM model or the HRRR.  These too can be a bit flawed in exaggerating land effects but generally are much more accurate.  I like the NAM 3k over the HRRR but they both have very similar outputs.  I would also look to the OFS models for both wind and current.  These are good but only run out about 48 hours.  

 

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
If you are using predict wind, compare the GFS and ECWMF models. Are they in agreement? If so then you can start believing the forecast. 

Keep watching the forecasted period as it gets closer, about 2x/day. Are predicted conditions changing much? i.e. are the models not really reflecting reality because the input conditions keep drifting. 
They are largely in agreement this morning.  I don't think the GFS is horrible at predicting bay conditions.

If I depart home on Friday, I'll have a sleigh ride down the Delaware bay on Saturday. If I depart home on Saturday, I will merely have "meh" conditions of light and variable breezes from mostly favorable directions on Sunday.  It's still far too early, but Mon/Tues look for a much nicer ride up the coast than Sun/Mon.

 

T sailor

Member
429
93
Chesapeake
If I were making the call right now, I would depart the Rhode on Friday transiting the canal on Sat, late morning.  Looks to be the best conditions for both the Chesapeake and Delaware parts of the trip. Maybe spend two nights in Cape May as Monday looks like the better departure for the Ocean leg.  High pressure looks to be locked in for M-F so you should have pretty decent conditions.  

 

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
If I were making the call right now, I would depart the Rhode on Friday transiting the canal on Sat, late morning.  Looks to be the best conditions for both the Chesapeake and Delaware parts of the trip. Maybe spend two nights in Cape May as Monday looks like the better departure for the Ocean leg.  High pressure looks to be locked in for M-F so you should have pretty decent conditions.  
I agree that Friday looks "better" for getting to Cape May but it's still "OK" on Saturday.  I agree with Monday departure for the Ocean leg.

If I work on Friday, I'll earn an entire extra day of vacation. My boss thinks I've taken Friday off, so I do have the flexibility. Let's give the forecast one more day to firm up.

 

T sailor

Member
429
93
Chesapeake
I totally hear you on the vacation time thing!  I get crap vacation (taking a leave of absence for this trip) and am always trying to optimize the time off that I do get!  I can see if it is only marginally better to go Friday than save the day and go Sat.

 

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
I built a route in Expedition running 66.5 NM from Chesapeake City to the Delaware Bay Entrance. Assumptions: motor continuously at 6 knots through the water, no affects of wind, Delaware Bay currents applied, and route is along main channel.

I ran about 20 optimization runs and found that the minimum time to run south from C City corresponds with departing at C City at LOW tide at Chesapeake City. The maximum time corresponds with departing C City at HIGH tide (opposite of what is said in the Waterway Guide). Runs starting before or after high and low tides have run times that fall in between the two runs starting at high/low tide.
Cheeze and rice, this has me departing Chesapeake City at 1:13am on Sunday if I want the 10 hour transit to Cape May. (Or, depart at 1:57pm but that has me arriving Cape May at midnight. No thanks. I don't want to arrive in a strange place at night.)

The difference between your models (best/worst times) is about 2 hours. If I leave Chesapeake City at 5am, I'll arrive around 4 to 6pm, which is fine. I will have light winds from a favorable direction on Sunday the entire day.

Cape May to Block/Cuttyhunk/Buzzard's Bay, Depart Cape May at 6am:

GFS and Euro match in wind direction and pattern. GFS is slightly more intense for a period of time with winds briefly getting up in the mid 20's along Long Island. Euro says low to high teens and that if I stay closer to shore by making sort of a "dent" in my rhumline that I'll stay in more comfortable breeze. I'm rooting for the Euro.

Either way, I'm going to do much better than a paltry 5 knots up the coast, which is my worst case scenario. 6 - 6.5 knots is optimum because it has me arriving in the vicinity of Cuttyhunk/Buzzard's Bay at dawn.

 
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El Borracho

Sam’s friend
6,349
2,385
Pacific Rim
Wow. Just go. I've never done planning like that. Go when boat and crew are ready. Racers worry about tides. I'd much rather wait around for the tide to change out on the water, even going backwards, than sit in a marina running simulations. Weather forecasts are good for tropical storms and major frontal activity. They are but virtual docklines for keyboard sailors and jawboning on the morning VHF nets. Especially on what amounts to a shakedown cruise for you where any tiny thing might return you to moorings after just five minutes. (I'll let myself out.)

 

Ajax

Super Anarchist
14,509
2,801
Edgewater, MD
Wow. Just go. I've never done planning like that. Go when boat and crew are ready. Racers worry about tides. I'd much rather wait around for the tide to change out on the water, even going backwards, than sit in a marina running simulations. Weather forecasts are good for tropical storms and major frontal activity. They are but virtual docklines for keyboard sailors and jawboning on the morning VHF nets. Especially on what amounts to a shakedown cruise for you where any tiny thing might return you to moorings after just five minutes. (I'll let myself out.)
Now, now I've never aborted a race or a trip due to minor adversities.  I pay attention to the currents in the Delaware Bay because I'm not interested in running my engine to the ground in a foul current. Most people in this area do.  All will be well.

 
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