Tides & Currents Flashcards
Tidal Advisory Broadcast
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.
Mean Range
5 - 6.5’
Diurnal Range
8.4 - 10’
Tides
Tide increases through the sound from North to South. Semi-Diurnal with Large Diurnal inequality.
Currents Admiralty Inlet
In Admiralty Inlet, currents are strong and subject to daily inequalities.
Admiralty Bay
Strong Currents
Pt. Wilson
Heavy rips N of the point. Rips are heaviest with W wind and ebb current.
Point Wilson to Point No Point
Tidal currents can have velocities of 2 to 7 knots. In the winter, when S winds prevail, there is generally a N surface drift which increases the ebb current and decreases the flood current. This effect is about 0.5 knot between Nodule and Bush Point.
Point Wilson and Marrowstone Point
Slack water occurs from 0.5 to 1 hour earlier near the shore than in midchannel.
Bush Point
The flood sets strongly toward Bush Point.
Mutiny Bay
There is frequently an eddy in Mutiny Bay
Double Bluff
Strong tide rips occur, particularly on the ebb with strong NW winds.
Port Townsend Canal
Strong currents through the canal. Strong eddies at the S end on the ebb.
Foulweather Bluff
At times the tide rips around and to the N are sufficiently heavy to be dangerous to small craft and to break up log rafts. This is most dangerous when the ebb current from the main body of Puget Sound meets that of Hood Canal off the point, and particularly so with the ebb against a strong N or NW wind.
Midchannel Bank
Strong cross currents exist.
