(1) You should verify these graphs before you use them.
If you don't know how to verify them, ask your local expert.
The original adjustment factors came from this url:
Yes, this is complicated, which is why you should not blindly trust it.
However, I've paddled Discovery Passage many times using the Orange Pt graph, it's been okay so far.
(2) NOAA uses the same current values for Orange Pt and Cape Mudge, but Cape Mudge is 5 minutes later.
So if slack at Orange Pt is 10:15, slack at Cape Mudge is 10:20
Race Pt is 5 minutes earlier than Orange Pt, while current values are 7/5 those of Orange Pt.
(3) Currents are not uniform across the width of Discovery Passage.
They are affected by the width and depth of the channel, and by the shape of the shoreline.
They are usually stronger on the east side. They are usually weaker near shore, unless the current hits a protruding or angled shoreline.
Some areas are prone to tide rips, others have boils and whirlpools.
Certain parts of the shoreline will have a counter current.
(4) Some areas of Discovery Passage are hazardous.
Seymour Narrows is dangerous except at slack, which can be very short. On July 4 2016, with a max ebb of 13 knots and a max flood of 15 knots, the time between 2 knots ebb and 2 knots flood was 35 minutes.
Slack time at Seymour Narrows can be busy as that is the safest time for tugs, barges, yachts, sailboats etc.
The whole area between Seymour Narrows and Race Pt is dangerous during a flood.
Whirlpools form south and east of Race Pt during a flood.
There are usually tide rips off Walcan, April Pt, Quathiaski Cove, and Cape Mudge.
There are swift currents at both ends of Steep Island.
There are boils at Yaculta Bank.
The ferry between Campbell River and Quadra Island is a potential hazard.
Beware the float planes that land and take off near Tyee Spit. There is a white light at the end of the spit that (usually) flashes as a warning.
The Husky boat ramp area (aka Big Rock) can be very busy with small boat traffic and is no longer kayak friendly. Ken Forde park is better.
There is sometimes low visibility due to fog.
A south wind can generate large waves, especially when it meets a flood.
A southeastly against a flood will form a dangerous tide rip off Cape Mudge.
Occasionally log booms are moved by tug from Menzies Bay to Gowlland Harbour.
(5) This graph is updated every day between 4 and 5 am,
if my home computer and my internet provider are both running and talking to each other.
So no guarantees.
If you find this useful, let me know at feedback at alyak dot ca .
(6) The harmonic constants for Seymour Narrows (hence Orange Pt) are the same as those used by DFO, while those for Campbell River are older.
Thus the tide heights will not exactly match the Canadian Tide & Current Tables. But they will match xtide.