Tides & Currents

Question 1

Tidal Advisory Broadcast

Answer 1

Seattle VTS will broadcast an advisory when tide level is predicated to be in excess of 11ft. Broadcasts begin at least 30 minutes prior to the predicted tidal level of 11ft and continue every 30 minutes until the predicted tidal level has dropped below 11ft. Vessel to transit at safe speed to reduce risk of wake damage when tide exceeds 11ft.

Question 2

Mean Range

Answer 2

7-8ft

Question 3

Diurnal Range

Answer 3

10-12ft

Question 4

Tides

Answer 4

Semi-Diurnal with Large Diurnal inequality.

Question 5

Rich Passage Current

Answer 5

Velocities increase from E to W. Strongest current observed are 4 kts on the flood and 5 kts on the ebb., between Pt Glover and Pt White. Currents of at least 6 kts have been reported at light 10.

Eddies and counter currents on the ebb reduce the effective width of the pass and increase velocities in the channel.

Outbound deep draft vessels making the sharp turn may be set well towards the E shore, making meeting inbound vessels stbd to stbd necissary.

Question 6

Port Washington Narrows

Answer 6

Tidal Current can be in excess of 4 kts, with rips off Rocky Pt on the W side of the N entrance to the Narrows.

Question 7

Elliot Bay

Answer 7

Tidal Currents have little velocity. At times during a falling tide, a current will set NW along the waterfront.

Question 8

Port Orchard

Answer 8

Tidal Current is week.

Question 9

Eagle Harbor

Answer 9

Minimal, varies with tidal influence.

Question 10

West Waterway

Answer 10

Strong currents on ebb and during freshets at the Fisher Mills wharf.