Confusing Tide and Currents Info for Malibu Rapids

[scross]

In double checking our Princess Louisa cruise itinerary, I found some very conflicting info for tide and current forecasts for Malibu Rapids. We plan on going through Malibu Rapids on August 30th and then coming out on September 1st.
I was told at the Points North Seminar (confirmed by other on line sources too) that the best way to determine the tides at Malibu Rapids was to add 35 minutes to the low water times at Pt. Atkinson and add 25 minutes to the high water times.
For August 30th, the Canada Fisheries and Oceans Canada website http://www.tides.gc.ca/eng/data/table/2 ... ef/7795#s4
says the Pt Atkinson low tides are at 6:08 AM and 6:48 PM with high tides at 1:47 PM and 11:14 PM. This would give Malibu Rapids times of 6:43 AM and 7:23 PM for low tide and 2:12 PM and 11:39 PM for max high tides.
I am assuming slack water at Malibu Rapids would be near the time of max low and high tides.
Two of the most popular referenced on line tide and currents website gives a very different set of times for minimum currents however! Dairiki.com shows currents at Malibu Rapids
http://www.dairiki.org/tides/daily.php/pli/2017-08-30
to be slack current at 12:02 AM and 9:03 AM with a low current (0.6 kts) at 5:13 PM.
Another site http://tides.mobilegeographics.com/loca ... 7&m=8&d=30 gives the exact same info as Diariki.com
Which one of these references these is right?
Can slack current times really be several hours different than max high and low tide times in the passes?

 

[Larry H]

First up, the tide table from Fisheries and Oceans is in standard time. Add one hour to the table reading for daylight time.

It is possible for the time of slack current to be different from the time of high/low tides. During the flood/ebb tide the water is moving into or out of the waterway. When high/low water is reached, the momentum of the moving water continues the tidal current for some time. In inlets with rivers, the ebb current can be stronger and last longer than the flood as the rivers add to the ebb.

I have always used the official Canada Tide and Current tables as I have found the various commercial publications sometimes do not match the official tables.

I would plan on arriving off Malibu Rapids early, perhaps 30 min. Stand off and check out the flow and the other boats entering or leaving. When you decide the time is right, put out a 'Security' call on VHF ch 16 to notify any other boats of your intention to pass thru the rapids.

I like to arrive before the slack preceding flood current if entering or preceding ebb current when leaving. That way the current will be changing in your favor at slack.

Once inside Princess Louisa Inlet, proceed at 'no wake' speed as a courtesy to the other boats. The vertical walls will reflect your wake and churn up the water. The folks already at the dock will not be happy if you speed to the dock dragging your wake with you.

 

[scross]

Larry - Thanks for the info! I did not catch that the Fisheries and Oceans tables were in PST. Correcting to PDT reduces the difference between high/low tide times and slack currents per the on line sources to about 2 hours instead of 3 hours.
To bad the F&O tables do not have current data for Malibu Rapids.
After reading your post, I called three commercial locations in the area and could not get a straight answer on the 2 hour difference between high/low tides and slack currents being accurate....
Knew about the no-wake zone in PLI and the use of Channel 16 to call out both directions. I think I will get there about 1 hour before the low current time to evaluate everything and get prepared. As long as I can go through the Rapids with 1 knot or so of current it should be OK.
Hopefully most of the smoke will be gone when we get up that way. Bad visibility here in Southern Oregon right now too.

 

[Red Raven]

Hi Al,

I was confused by this as well. We went to Princess Louisa in late June. Fantastic place. You won't regret it.

We used the Point Atkinson reference and found it was spot on. Note that the Point Atkinson reference is referring to slack "current" at Malibu vs. high and low "tides" at Point Atkinson. They are many miles from each other so would not normally have any relationship but someone at the Canadian Fisheries and Oceans has figured out there is a correlation.

I do not know what the other web sites use for their reference as there is no tide or current station at Malibu. One thing to note that I think is exacerbating the difference in times on this particular day is that the currents are very minimal even worse case (2.5 knots). There is only around a 6 foot tide change at Point Atkinson in the morning low and less than 2 feet in the afternoon high.

The good news is that you likely will have a very wide range of transit times. It looks to me that anytime around either reference will be relatively slack. As always, check what's happening as you approach to make sure it is safe but it looks to me you are good to go on entry between around 7 and 10 am and 3 to 6pm PST on Aug. 30 (Or essentially anytime during daylight hours after 7 am since you can easily handle 2.5 knots which would be worse case!).

Curt

 

[scross]

Thanks Curt! I was hoping someone who had been there recently would explain how they calculated the slack current and if it was accurate. Yes, I see the reference here
http://www.princesslouisa.bc.ca/princes ... l-plis.php
says Malibu Rapids is a secondary current station based on Pt Atkinson tides. For me, this verbiage was a bit like mixing apples and bananas but when read carefully makes sense.
Not sure why both the on-line sites I linked earlier are a full two hours off! Since it's a 3-4 hour retreat down the Jervis Inlet if you get the afternoon slack times wrong I really wanted to get this right.
I'll plan on getting to Malibu Rapids by 2:45 PM then and wait for slack current at 3:12 PM. The water level should be high and the current at a manageable rate for a number of hours around that time as you said. Still, prefer to make getting through a non-event rather than an adventure.
Went through Gabriola Passage three weeks ago into a 2.4 kt current just to see what that was like. Following a couple of sailboats convinced me I could do it too. Other than maneuvering around a couple of eddies and dodging some big logs it very straightforward.
We have an "extra" 3 days built into the schedule to get across the Strait just in case of adverse winds and/or waves. Looking forward to the trip and getting out of the heat and smoke down here!

 

[knotflying]

If this is any help. What I did was set the mouth of Malabu Rapids as my destination. I was then able to adjust my speed (faster/slower) to arrive exactly when I wanted to. Everyone is usually mulling around outside waiting for the first boat (guinea pig) to go in and then report back. It was a fairly benign experience if you time it correctly.

Enjoy!!

 

[walldog]

Be aware you may encounter a go fast tour boat mid stream that did not announce their intentions. Be watchful and careful and no problems.

 

[Spinner]

The timing of the Malibu Rapids is very well explained in an entry in the current Wagonner Guide.

Use the Ports & Passes book, which covers Washington, British Columbia and SE Alaska. It's corrected for daylight savings time, and is always correct!

 

[scross]

Thanks for all the good info on PLI!
In planning for this trip I had read the section in the Wagonner Guide and, with the info I heard at the Points North Seminar, thought I had the slack water timing figured out before running into the conflicting data. Messed up on not knowing the Canada Fisheries and Oceans data was not corrected for DST.
My 2017 copy of Ports and Passes is sitting in Our Journey on the dining table - which is 535 miles from where I am writing this at my home. Good to know that it's data is correct and that I don't have to worry about a daylight time correction with P&P.
So, not having the P&P reference handy, I went on line trying to get the info. And that's when I ran into the conflicting data. Usually Dairiki.com has been accurate in it's slack water times for other passages when I have referenced it in the past. But obviously both Dairiki.com and tides.mobilegeographics.com are really messed up about slack water times at Malibu Rapids!
And thanks for the heads up about some of the tour boats not bothering to announce on Channel 16 when going through Malibu Rapids. I know you are suppose to pass port-to-port in those situations but there's not a whole lot of room right there!
Also, I've been watching the smoke from Camp Malibu at their webcams. http://www.malibuhydro.com/
Hasn't been very scenic up there these past two weeks. Hoping that the forecast change in the weather does clear things out later next week.

 

[Larry H]

In Canada, if the current is running in a pass, the boat going WITH the current has 'right of way'. The boat going against the current shall hold and maneuver to allow the other boat to pass.

This is because the 'with the current ' boat has less maneuverability than the 'against the current' boat.

 

[scross]

Eleven months later we made it to PLI for 3 nights. Went in at low, low slack within 2 minutes of published time and still encountered 4 knots against the bow. Said at the time, “Well if that 40 ft sailboat that just cut in front of me makes it, I can too!” Going out 3 days later at 40 minutes before high slack was a cakewalk - less than 1 knot! Ports and Passages references were the key.
Beautiful place! A must see for all PNW tug owners!!

 

[Red Raven]

Al and Vicki,

Enjoy your time at PLI. Glad to hear you made it with no problems. It is a special place!

Curt and Tracy