Re: Bainbridge Currents for Sept 12, 2015


Steve Bennett
 

Tom,
Nice work.  I defer to your analysis. You have caught my error:  I either foolishly or mistakenly equated the flood at Agate and Rich. Slack at Rich is over an hour later at noon.  The tide is at ebb in Rich until then. 
I think the Counter-Clockwise distance to Agate Bridge from Fort Ward is 15 miles, however.
 
Steve

From: "'Tom Kreyche' tkreyche@... [SoundRowers]"
To: 'Steve Bennett' ; SoundRowers@...
Sent: Wednesday, September 9, 2015 10:47 PM
Subject: RE: [SoundRowers] Bainbridge Currents for Sept 12, 2015

 
Steve,
 
Here’s my revised analysis based on a start at Ft. Ward at about 9:45 and a 4 hour racer. This disagrees with yours a fair bit, except we’re both suggesting CW would be best if the predicted N wind sticks.
 
Any other opinions?
 
…Tom
 
Overview
This estimate is for Saturday September 12, with racers starting from Fort Ward. Without considering wind, CCW may be more favorable since racers will spend less time fighting the current in Rich Passage. CCW may also have a slight advantage with the current through Agate Passage. However winds are forecast to be out of the N, which would tip the balance towards CW direction. The 9-mile E side of the island is exposed and a downwind leg is preferred.
 
Counter-Clockwise
A 3kt ebb will push racers to a quick exit from Rich Passage. On the S and SE end of the island a weak ebb will be beneficial. By the time racers reach Agate Passage (11 miles from the start) at about 11:15 a.m., they will be aided by a weak but building flood of 1.5 to 2kt. The current will aid racers on the NW side of the island, and transition to hindering them on the SW side as the flood into Rich Passage takes effect. A 2kt flood tide will hinder the entrance into Rich Passage with it weakening to 1kt near Ft. Ward.
 
Clockwise
Racers will immediately face a 3kt ebb through Rich Passage, and will also be hindered around the SW side of the island. The W and NW should be mostly slack. The entrance into Agate Passage is about 15 miles from the start - it is slack at 10:47 and builds rapidly to flood. Early arrivals will see slack or a light flood, but later arrivals will face 1.5 by 11:30 a.m. A weak flood will aid racers on the E side of the island and back into Rich Passage. One strategy would be to work hard the first part of the race to get out of Rich Passage and through Agate early, then cruise downwind on the E side of the island.
 
Tidal Currents
Agate Passage N End - Flood Direction, 230 True, Ebb (-) Direction, 032 True
Max Current -2 kt (ebb) at 7:44 a.m.
Slack Water 10:45 a.m.
Max Current +1.7 kt 2:03 p.m.

Agate Passage S End - Flood Direction, 216 True, Ebb (-) Direction, 037 True
Max Current -3.9 kt (ebb) at 7:56 a.m.
Slack Water 10:48 p.m.
Max Current 4.2 kt (flood) 2:10 p.m.

Rich Passage W End - Flood Direction, 238 True. Ebb (-) Direction, 055 True
Max Current -3.4 kt (ebb) at 9:05 a.m.
Slack Water 11:29 a.m.
Max Current +3.2 kt (flood) at 2:55 p.m.

Rich Passage Off Pleasant Beach
Max Current  -3.1 kt (ebb) at 9:26 a.m.
Slack Water 11:59 a.m.
Max Current 1.7 kt (flood) at 2:48 p.m.
 
 
 

From: Steve Bennett [mailto:bennett_seattle@...]
Sent: Wednesday, September 09, 2015 4:43 PM
To: tkreyche@...; SoundRowers@...
Subject: Re: [SoundRowers] Bainbridge Currents for Sept 12, 2015
 
So then, with the start now at Fort Ward, our hat is cocked; the tables turned.  Here's my new read:
 
Leaving Fort Ward, clockwise, within an hour of slack, a 5 hour racer should arrive at the Agate Pass Bridge with a favorable current of 2 kt, and slower paddlers will benefit even more.  Had he opted for counter-clockwise he would be fighting 3.5 kt at the bridge.  There'll likely  be no contrarians this year.
 
Also for your planning:
 
·         It is 15 miles from Fort Ward to the Agate Pass Bridge counterclockwise.
·         It is 11 miles from Fort Ward to the Agate Pass Bridge clockwise
·         Halfway is at about the middle of the big bay that extends from Agate Point to Point Monroe (which is just around the corner to the north from Fay Bainbridge)


    Any other thoughts ?
 
Steve



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