swiftsure.org web sitecanuck.seos.uvic.ca/swiftsure/swiftsuretides2016/... · jdf-w jdf-e 1 m/s = 2...
TRANSCRIPT
![Page 2: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/2.jpg)
Tidal Heights and CurrentsTidal currents “flood” in from the ocean on a rising
tide and “ebb” out to the ocean on a falling tide.
![Page 3: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/3.jpg)
Surface Slope Drives Tidal CurrentsCurrents flow down-hill, from higher to lower
water.
Racers needn’t worry too much about tidal height, except when anchoring or rock hopping.
Local current patterns are determined by the channels, straits, and sounds in response to these ocean and basin “waves” or “sieches”.
Mean flows in late May: surface water exiting Salish Sea (¼-½ knot), some of this is in the tidal current table values. 2016: >¼ knot
![Page 4: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/4.jpg)
Deep vs Shallow Tidal Currents
Deep water has more inertia, will ride “up-hill” to stop, reversals are lagged/delayed.
Shallow and boundary layer flows have more friction (turbulence/drag), can be slower & will stop and reverse sooner.
Lateral convergence or vertical shoaling can result in accelerated flows.
![Page 5: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/5.jpg)
Points of Sail in a CurrentAlthough the speed of the current is low
compared to the wind (hopefully), a few knots of currents over time will make a difference.
Avoid currents on the windward quarter.
Heading into a tide, try to keep the tide under the leeward bow, (lee-bow).
A current under the lee side is always better than under the windward side: apparent wind and lift.
![Page 6: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/6.jpg)
Tidal Current Station
Tidal Height Station
![Page 7: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/7.jpg)
Reading Tidal Height Tables
PDT=PST+1Victoria (CHS)
![Page 8: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/8.jpg)
Tidal Height: May 28 – 30, 2016
![Page 9: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/9.jpg)
Tidal Current Station
Tidal Height Station
![Page 10: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/10.jpg)
Reading Tidal Current Tables
PDT=PST+1Race
Passage
1 knot =
~0.5m/s
- Ebb
+ Flood
![Page 11: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/11.jpg)
Tidal Currents: May 28 – 30, 2016
Flood
Ebb Start Rounding Finish
Race
Passage
JdF-W
JdF-E
1 m/s = 2 knots
![Page 12: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/12.jpg)
Foreman, et al, 2004
![Page 13: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/13.jpg)
![Page 14: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/14.jpg)
![Page 15: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/15.jpg)
![Page 16: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/16.jpg)
![Page 17: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/17.jpg)
Tidal Currents: May 28 – 30, 2016
Flood
Ebb Start Rounding Finish
Race
Passage
JdF-W
JdF-E
![Page 18: Swiftsure.org Web Sitecanuck.seos.uvic.ca/Swiftsure/SwiftSureTides2016/... · JdF-W JdF-E 1 m/s = 2 knots. Foreman, et al, 2004. Tidal Currents: May 28 –30, 2016 Flood Ebb Start](https://reader034.vdocuments.us/reader034/viewer/2022051921/600ea4cf2494655850592049/html5/thumbnails/18.jpg)
Good Luck!At Swiftsure.org
Race Info Currents During Race
(please save PDF files, don’t print )
Richard Dewey