Keystone confuses me

[LCF]

It's a busy weekend . . . Quite a while back, I signed up to compete in a horse show in Coupeville this weekend, but then one of Peter's OW students absolutely HAD to get his OW dives done this weekend, so the upshot is that we agreed to meet him at Keystone in the mornings and get the dives done, since my ride times had all come in in the afternoon.

I was very nervous about what kind of experience he was going to have, because my calculations showed that we'd be doing at least the first dive on a strong ebb current, and I had been told those are the worst conditions at Keystone. But time trumped tides today, so it was going to be whatever it was going to be.

The student is the son-in-law of my favorite dive buddy, who was bringing him up to Keystone, which meant that while Peter was teaching, Kirk and I were going to get to do a fun dive. But I didn't even bring my camera, because the last time I dove there, the current was so strong that I really didn't get any good photos, and from what I thought I knew, today was going to be worse.

And in fact, when we got in the water, there was a strong inshore current that made it difficult to get distance from the beach. But when we got to about 25 feet of depth, where we set Peter's float, the current . . . DIED. From there, to the very end of the jetty, there was no water movement at all, and the viz was really quite good. I love Keystone, even when it isn't perfect, but today it was close. We found all kinds of fun things, including a huge ling cod with a brilliant, tiny longfin sculpin perched on his head. Coming back, we did something I don't usually do, which is to move up into the water column and swim among the metridiums and into the kelp stipes. Today, they were full of black rockfish, and outside them the water was literally thick with shiner perch and what I think were sand lances. In addition, we were treated to a good-sized school of BIG pile perch, who would swirl into view and out. I think we sat for a solid ten minutes, just hovering and reveling in the life we saw all around us.

On the way back in, at about 42 minutes into the dive, we started feeling a current pulling us OUT, and it got stronger and stronger as we made our way back to the beach. We were out of the water at about 11:30, which is when the Admiralty Inlet current charts say we should have had slack, but we sure didn't.

It seems clear to me that whatever information I am using to plan these dives, it's not the right stuff. Can anybody give me some better ideas on how to figure out when Keystone is going to be fun? We were very pleasantly surprised today, but I'd rather not have to depend on that

[ljjames]

Fischnallers book gives a good description of what kind of chaos goes on with the currents out there.

First off, I tend to dive Keystone on exchanges that resemble what you'd want to dive the big wrecks, mostly because I want an hour and half or so to take pictures of all the color, and i'd like a second dive there if possible. (for an example, look at Sept. 2nd, you could get out there at a reasonable hour and dive your brains out all afternoon into evening)

Using Fishnaller as a guide, slack before flood today would have been around 10:50 give or take (-:31 min correction to Admiraly) So i give myself 30 min of wankery (I always assume it takes us longer to actually make the trek to the water and ready to dive than we think with cameras and fins and buddy checks and forgotten gear, etc... ) so subtract :30 min from adjusted slack before flood and I want to bracket the slack so subtract another :30 min. That means I'd want to hit the water on that dive somewhere around 10:00, which it sounds like you did.

Additionally, per Fischnaller, there is a second 'slack' during the flood exchange which is why people sometimes get confused. If they don't plan for any adjustment and then have a bit of time spent getting to the water, more often than not they hit the second 'slack during flood' (the flow reversal) and never realize that they actually missed the true slack.

There is no real slack before ebb, it just slows down (because of that flow reversal aka second slack of the flood which I guess I generally considered the slack before ebb and subtracted something like 3 hrs , but you can still find the jetty eddy to play in, but be mindful of the split flow during the ebb, where the current is going inshore for the first half of the jetty, swirly/eddy in the mid jetty, and then tries its best to introduce you to the ferry as you get closer to the end of the jetty

[LCF]

Yes, those are the conditions I'm familiar with at Keystone -- an inshore current to start, nothing in the middle, and turn around when you begin to feel the water plucking at you.

For some reason, my memory was telling me Keystone wasn't IN the Fischnaller book. Now I'm a bit embarrassed, because I should have just looked it up.

[seainggreen]

IIRC, Keystone wasn't in all of the Fischnaller editions, but then again, I haven't looked at other editions than what I own in a very long time.

What I do know is that typically it seems like I've had to plan 30 minutes earlier than what even Fischnaller would say to make the dive work, and I have only had those "dead calm" mid-dive moments on very minimal exchange days. YMMV. I just know that earlier this month when I dove there the correction seemed to be WAY off (eg more than 1.5 hours off). Weirdness.

Laurynn

[fmerkel]

[YMMV. I just know that earlier this month when I dove there the correction seemed to be WAY off (eg more than 1.5 hours off). Weirdness.]

May be something to that. Did Sunrise about a month ago, smallish exchange, probably 1/4-1/2k current the whole dive only slacking at the end for a ride NOT home.
Did DIW on the 16, quite small exchange, expected negligible current. Another 1/4-1/2K the whole dive only slacking at the end of the dive, almost an hour later than expected.

[LCF]

Although I didn't dive the following day, the class did . . . and slack was MUCH later than one would have predicted by the -30 strategy. We talked at some length with the Whidbey Island Diving instructor who was there, and he said predictions are only that, and you just have to watch the kelp and the current lines in the water, and figure out when to go.

We planned the GUE Seattle BBQ trip for the morning slack, and that's where we fought current like crazy the whole dive.

Either Jan has tremendously strong legs, or he's got the secret code . . .

[KneeDeep]

Either Jan has tremendously strong legs, or he's got the secret code . . .

I'm going to say both

[ljjames]

The slacks differ, you can't just call them 'slack' the predictions vary massively with slack before ebb vs slack before flood.
Things also change depending on the exchange. If you haven't had a chance to look at it, the Canadian Current Atlas (one time purchase) that accompanies the Washburn tables show the variability on current in general quite well in a more comprehensive manner I think than standard run of mill tables/charts. Too bad keystone is just outside of their reach (in the version I have at least). What i use it for is to learn about how the underwater bathymetry might possibly be impacting currents, including the upwellings, the flow reversals, etc...