Would like a buddy for Skyline 5/21

[dieseldude]

this is a morning dive-before 9. We can argue about which current table to use as it gets closer. I would prefer someone who has done this site at least a few times. I have only done it once & wouldnt want to risk someone else because of my lack of familiarity with the site. That said, experienced divers only. current will be an issue. This is still a couple weeks out so I'm hoping someone can swing playin' hookie on a friday.
MJ

[fmerkel]

It's not an exchange I'd recommend unless the date is locked in and you are good with outgoing current.

Right now my theory is the ebb current needs to be larger than the flood current to have a successful reversal.
5/21: 0.3E > 9:44 AM slack > 0.7F

A couple exchanges I've done like this had about 1/2k outgoing with no reversal. If you go shallow, right up to the rocks in a few feet of water, you get out of the current and can make your way back. Lots of stuff to hold on to so not a big deal if you are OK with current and the long swim.

Fritz

[dieseldude]

This is where the different prediction sites mess with me. I have max flood 0.7kt at 7:44am, slack 9:07am, max ebb -1.3 at 1:38m. If I'm understanding you right, the ebb is bigger on this run. The one time I did this dive before, we had to work to get back but it wasnt that big a deal. We stayed shallow as you said. Do you have a link for your current site? I'm using Plan your dive. I have good luck with it in most places.

[fmerkel]

NW Shore Dives (3rd ed - Burrows Pass) > Rosario Straight indicator: -32"

I'm using a commercial Tide/Current program (see below).
JTides has this for Rosario: 0.2F > 10:16 AM > 1.3E
[http://www.arachnoid.com/JTides/]

Whack off 30" and slack is the same. Different currents as my program calculates for the Pass, but the ebb is still larger than the slack. I think when it's that way even if you dive the correct exchange it still does not reverse. I've only done 2 of when ebb was larger and neither cooperated. The fist one was a bit unnerving as I had a new buddy, low viz (I've learned to watch the Skagit dump) and she had never done Skyline. The next time the exchange was very similar so was expecting a swim...and got it.

I haven't used Plan Your Dive before. Googled it and came up with this:

Plan your dive for Skyline-5/21/10

Is that what you used? I'll have to have my wife plug Sunrise into that and see what she finds. She's a Sunrise wizard-a challenging site sometimes.

Here's a good day using my program:

Tides and Currents for Skyline-4/11/10

Check out that last day when you had to crawl back and see how the current ratio stacked up. I'll bet it's ebb larger than flood.

Fritz

[dieseldude]

That is the site I use the most. I'd be interested to hear what you think of it. I believe it's originator is a member of our board.
I'm gonna take your advise on this & look for another dive. I will try to get back to skyline another day. Very cool info to have. Thank you for that. I'll run a search based on that info.
MJ

[whatevah]

Here's a good day using my program:

Skyline_4_11_10.png

Check out that last day when you had to crawl back and see how the current ratio stacked up. I'll bet it's ebb larger than flood.

Fritz

Fritz somewhere along the way you got your floods and your ebbs flipped. You want the ebb larger than the flood for predictable turn-around. In Burrows Pass the floods run to the west and the ebbs run to the east. The site is best when there is either minimal tidal movement for an extended period (ie, swim out and swim back) or timing it around high slack (end of the flood and the beginning of the ebb - so you can drift the flood out to the west and then drift the ebb back to the east). I sometimes use the same program you do, and it has a current station for Burrows Pass as you've noted. Using that current station I feel that the reverse to an ebb is unpredictable if the peak of that ebb is less than 1 knot. If you don't have that program, the best you can do is use the Rosario Strait station - apply the offset to predict the time of slack, and don't do it when the predicted ebb in Rosario is small (under 2 knots).

[fmerkel]

Fritz somewhere along the way you got your floods and your ebbs flipped. You want the ebb larger than the flood for predictable turn-around. In Burrows Pass the floods run to the west and the ebbs run to the east.

That's interesting input and why I'm still gathering data for this dive. Here's a list of some of my dives there:

9/24/05-good, 11:20 splash - 2.4kFld > 11:51slack > 0.3k Ebb
9/05/08-very good: 10:30 splash - 2.35k Fld > 10:52 slack > 0.33k Ebb
4/11/10 Skyline - very good: 4:10 splash- 1.3k flood > 4:30 PM slack > 0.7 ebb

(date not noted) v-bad: 12:30 splash-0.5k Fld> 1:01 slack>1.1k Ebb
4/23/04-bad: 12:00 splash-0.2k Fld> 12:12 slack > 0.8k Ebb

This is all using [Tides and Currents - Fidalgo Head - Burrows Is, between]
Notice on all the good ones the flood is larger than the ebb.
On the 2 outings where the current did not reverse the opposite is true.
I've got maybe 12-15 good dives and 2 that did not reverse. That's where I came up with this theory, but it's still a theory.
It's a long enough drive that I'm not inclined to run up there to merely test it for yucks but sure am interested if I'm on to a viable predictor of reversal or not.

Several of my dives have the ebb less than 1K as long as the flood is larger. The 2 days the reversal did not happen were very flat exchanges. The Anacortes dive shop had indicated not to do it on very low exchanges but I never knew exactly where that cut off is - still don't, but I'm working on it.

[whatevah]

4/23/04-bad: 12:00 splash-0.2k Fld> 12:12 slack > 0.8k Ebb

This is all using [Tides and Currents - Fidalgo Head - Burrows Is, between]

Hrm. Just taking that one day as an example, I see that we're working with different data. For 04/23/04 at that current station I have...

04:23 0.7k Flood
06:13 Slack
09:47 1.3k Ebb
14:17 Slack
17:29 2.9k Flood

Looking at my data, I'd have been looking at an 05:50 splash that day.

Hey - I haven't dove there in a while - maybe we can get together for a dive sometime - test our theories.

I'm thinking of heading to Keystone to catch the late afternoon slack today if anyone's interested in joining me. Mr Kocian?

[fmerkel]

OK-scratch 4/23/04: That's a Friday and I was sure NOT at Skyline.

Should be 4/23/06; 0.2F > 12:12 slack > .08E (Fidalgo-Burrows)


just thumbed through my old log and copied down know Skyline dates and I'll look them over later against the program.

Something I've found out is the Program is OLD (though it still seems to calculate correctly), and daylight saving time is keyed to the old switch over day and is not in synch with the new daylight saving switch. Should have been OK for this date but I could have been off an hour for some which would be a lot at Skyline for some exchanges.

I've obviously got to work on this some more. I'll report back after some data crunching.

Love to meet up with you on a dive at Skyline. It's one of my absolute favorite shore spots. Actually, it's just one of my favorite spots.

Fritz

Skyline-4/23/06: no current reversal

[dieseldude]

Let me know when you are diving Skyline Fritz, you owe me one anyway for trashing my big plans
I live close enough & like this spot enough to want to get it figured out. We'll put together a dive site listing report or something to report the results. And if we guess wrong...like I said, I've had the experience of fighting my way out & it wasnt that big of a deal. I'm glad people like you are out there working out the details for the rest of us.
MJ

p.s. Just remember to bring an extra tank cause we gotta do a 2nd dive somewhere to make the trip worhwhile.

[fmerkel]

Well, given new possible interpretations from whatevah and my apparent level of confusion (jeez, off by 2 YEARS) I think you oughta go up there and get some data. Report back.

I got kitchen painting, aquarium duty tomorrow, club dive planning this weekend, and sundry stuff so I may not get to my Skyline numbers for a few days. I'll kick the thread when I do.

Fritz

[fmerkel]

Got to my Skyline logs quicker than I thought.
I've got 18 dives since 2002. 16 were good, 2 did not have current reversal.
In all good dives the flood current exceeded the ebb.
In all non-reversal (outgoing) dives the ebb current exceeded the flood.
In one case they were equal and it was fine.

The good ones ranged from:
11/30/03 - good: 3.1F >11:02 > 0.8E
7/21/2007 good 10AM splash - 0.7F > 10AM slack > 0.4 E. Minor current.
And many variables in between.

The bad:
3/26/06-bad: 12:30 splash - 0.5k Fld>1:01 slack>1.1k Ebb
4/23/06; bad, but not as bad as 3/26/06: 12:00 splash - 0.2F > 12:12 slack > .08E

The equal:
5/25/03 - good: 0.5 >2:19 > 0.5E manageable out current. Switched late.

All data taken from [Tides and Currents ver. 1.05 (old)] It's up to version 3.6 now.
http://www.nobeltec.com/products/prod_tides.asp
I used [Fidalgo Head-Burrows Island, between]

Until proven otherwise, I'm sticking with my theory.

Fritz