Help Predicting Tides

[Graeme]

Hi, I signed up on these forums to hopefully organize some dives in the area. But first I'm hoping someone will be kind enough to help me out with predicting tides. Basically, my attempts in the past to hit slack tide haven't been overly successful, so I figure I must be doing something wrong. It's not rocket science, but it's one of those things that is never really taught in class.

I think the best way for me to learn is using a realistic scenario. As an example let's say that this Friday I'd like to head over to Titlow Beach and do 2 or 3 dives (not sure if 3 is really possible there). For assumptions sake, I expect the shallow dives to take 40 minutes each, and surface intervals of 30 minutes.

If this was you planning the dive, step by step (please include links to actual websites used) how would you calculate safe times and what schedule do you come up with? Please avoid hypotheticals if possible, pretend you are actually doing this dive: I'd like to see the actual schedule you get for this scenerio and see if I can get the same answer myself.

Thanks in advance to anyone who may be able to help me. This is a topic that drives me nuts, and yet at the heart of it I know it's not that complicated.

[cardiver]

For Titlow I would get in the water at around 1645 for a 60-70 minute dive. After the first dive I would pack up my gear and head to Les for dives number two and three.....

[pogiguy05]

I cannot say that I am great at predicting them either but I do have some insight. For places like Day Island Wall, Titlow, Sunrise it is best done when there is a very low exchange between high and low tides. There is a link on this board for tides http://www.dairiki.org/tides/daily.php/sea which uses a wxtide program that you can download onto your computer also. I am sure more will chime in that know more, but I will say this expect to hear about your 30 minute surface interval not being the minimum 60 minutes.

[LCF]

Given the shallowness of Titlow, I'm not sure anybody cares that you sit out 60 minutes between dives.

If you look at the printout from the dairiki site for Friday, you see a long steep flood tide in the early morning, and then a very small afternoon exchange. You can cross-check this by going to the lower right hand corner and clicking on "other current stations", and looking at the data for Tacoma Narrows, North End. It shows a small ebb and a small flood current in the afternoon. Currents at the Narrows are stronger than those at Titlow, which sits in a bit of a backeddy. My guess is that you could probably do two dives in the afternoon there, and would have some mild current to deal with, but nothing horrible. (But don't go diving on my advice and then blame me if I'm not right!)

The Northwest Shore Dives book has current correction times for a wide variety of local sites, and they're pretty accurate. But the first thing you have to decide is whether the exchange you're looking at is safe for the site you contemplate at all. Places like Day Island Wall, for example, can get downright scary on larger exchanges, especially if you don't pick slack precisely (she says, having waded a couple hundred feet against the current after three minutes underwater at the wrong time). But some sites aren't good to dive on exchanges that are too small, like Skyline. And some are deceptive, like Keystone, which is diveable on fairly good sized floods, but not on ebbs.

The books are good, and picking the brains of the most experienced local divers is good, too.

[dwashbur]

The best advice I can give you about predicting the tides and currents is to take Mischi's course on the subject. Details are at pelagiascuba.com and the course is WELL worth the price of admission. That doesn't help in the short run, but it will definitely pay off in the long run.

[Dusty2]

My best advice is to call the local shop and ask before attempting any current sensitive site that you are unfamiliar with. They have actual experience with the sites and will be able to help. Getting it wrong can be more than just scary. It can be downright dangerous if not life threatening. Every site has it's quirks and the charts are seldom right on for a specific site. Make sure that you read the proper chart type for where you are going to dive. I dive Hudson point at Port Townsend allot and I can tell you if you go by a tide chart there instead of the proper current station your in big trouble. The big secret is knowing which station to read and what the time offsets will be for your site.

[defied]

You can also click somewhere on my sig below.

D(B)

[gcbryan]

Ok, for Friday Sept 11...

First look at tides to find the range between high and low tides. If it's 3 feet or so it's a low exchange, if it's 10 or more feet it's a high exchange, in between ...you get the picture!

The size of the exchange determines how much water will be moving that day and in practical terms how long you will have at slack and how much current you will have to worry about after slack.

I usually use : http://tbone.biol.sc.edu/tide/sites_uswest.html

Pick a location near your site, in this case Tacoma Narrow South End current (midstream).

Use this for the current predictions find something for the Narrows without the word current and check this for tides.

Tides for this Friday at the Narrows are low, 10.59 feet high tide to 7.72 feet for low tide so a difference of 2.87 feet...low exchange.

Now check the current chart. Slack before ebb is at 11:45 am, according to the Northwest Shore Dives book (get this book) apply a correction for slack before ebb of +:33 minutes so that would make slack before ebb at Titlow 11:45 + :33 so 12:18pm.

You will have about an hour before you are looking at 1 knot currents (mid-channel), less where you are but still that site is a current sensitive site.

I would get in the water around 11:45 am and do one dive. Then go to Les Davis or Lobstershop Wall for the second dive.

There is a second slack (before flood) at 5:28pm or 5:23pm with the -:05 correction from the book so maybe get in a little before 5:00pm and again do the second dive elsewhere as the currents mid-channel will be a knot or so by the end of your first dive.

There is a lot of folklore about when you can and can't dive but it's really not that complicated. Once you understand throughly how it works and have a little experience with it you can dive most sites on all but the largest exchanges.

Some sites are better to play with current while you are learning such as Keystone and even Sunrise. Sunrise is close to shore as is Keystone and Keystone is a jetty and current can't go through the jetty...it can go along it however!

Day Island is best to do after you have a little more experience since it's further from shore and any mistakes are therefore magnified. I would go to Skyline on any but large exchanges but only at slack before ebb.

Deception Pass...limited opportunities mainly in late winter and early spring.

That's the main current shore dive sites that I can think of at the moment. I'm sure I've forgotten some. OK, Agate Pass maybe some shore dives in the San Juan's.

If you run into current at Titlow get to a shallow area,beach or whatever and then make your way back to the entry.

[HydroGirl]

I would have to agree with taking a class.
Also, keep in mind that slack isn’t necessarily a stop in water movement.

[LCF]

There are other current-sensitive sites -- you can get thoroughly spanked at the Mukilteo Lighthouse Park, for example, or the Alki Junkyard.

[Graeme]

Thanks everyone. Some general comments: I realize asking the dive shops is the best method, but at the same time I don't want to have to take 10 minutes of someone's time (and put all my trust in them) every time I want to go to a site that may be current sensitive, particularly if it is a site I know.

As for courses, any recommendations (links or something), I don't see this sort of course advertised much.

Also that planyourdive site is awesome.

Anyways, I'm going to go a bit deeper with gcbryan's post since this is the sort of example I was hoping to see since it makes it a bit easier to work off of.

The size of the exchange determines how much water will be moving that day and in practical terms how long you will have at slack and how much current you will have to worry about after slack.

If the exchange is too high, does it mean the site isn't diveable that day or just that you will have a shorter dive / need to be more careful planning? What is generally considered the highest acceptable exchange if you're willing to dive in some current but nothing dangerous (rule of thumb: I realize there's no magic number).

Tides for this Friday at the Narrows are low, 10.59 feet high tide to 7.72 feet for low tide so a difference of 2.87 feet...low exchange.

Now check the current chart. Slack before ebb is at 11:45 am, according to the Northwest Shore Dives book (get this book) apply a correction for slack before ebb of +:33 minutes so that would make slack before ebb at Titlow 11:45 + :33 so 12:18pm.

Where did this 11:45 come from? I see high tide is 11:49, but not sure what the "current chart" is you're referring to?

... so 12:18pm

You will have about an hour before you are looking at 1 knot currents (mid-channel), less where you are but still that site is a current sensitive site.

I would get in the water around 11:45 am and do one dive. Then go to Les Davis or Lobstershop Wall for the second dive.

I think this is where I need the most clarification, where did you get at what point you have 1 knot currents? Is this related to the exchange amount?

Also, generally speaking what current levels start to be considered dangerous?

And why 11:45 (about half an hour before slack), is this also based off what point the current speed drops to an acceptable level? Related to level of exchange?

Thanks again, this has been very helpful although I'm still not quite there.

[CaptnJack]

Graeme you are looking at tide charts (height of water). You need to be looking at current charts (horizontal movement of water), gcbryan is looking at current charts. Titlow is based on Tacoma Narrows, north, current tables.

Yes there are plenty of sites which are not divable on certain days or even months.

[gcbryan]

Thanks everyone. Some general comments: I realize asking the dive shops is the best method, but at the same time I don't want to have to take 10 minutes of someone's time (and put all my trust in them) every time I want to go to a site that may be current sensitive, particularly if it is a site I know.

As for courses, any recommendations (links or something), I don't see this sort of course advertised much.

Also that planyourdive site is awesome.

Anyways, I'm going to go a bit deeper with gcbryan's post since this is the sort of example I was hoping to see since it makes it a bit easier to work off of.

The size of the exchange determines how much water will be moving that day and in practical terms how long you will have at slack and how much current you will have to worry about after slack.

If the exchange is too high, does it mean the site isn't diveable that day or just that you will have a shorter dive / need to be more careful planning? What is generally considered the highest acceptable exchange if you're willing to dive in some current but nothing dangerous (rule of thumb: I realize there's no magic number).

Tides for this Friday at the Narrows are low, 10.59 feet high tide to 7.72 feet for low tide so a difference of 2.87 feet...low exchange.

Now check the current chart. Slack before ebb is at 11:45 am, according to the Northwest Shore Dives book (get this book) apply a correction for slack before ebb of +:33 minutes so that would make slack before ebb at Titlow 11:45 + :33 so 12:18pm.

Where did this 11:45 come from? I see high tide is 11:49, but not sure what the "current chart" is you're referring to?

... so 12:18pm

You will have about an hour before you are looking at 1 knot currents (mid-channel), less where you are but still that site is a current sensitive site.

I would get in the water around 11:45 am and do one dive. Then go to Les Davis or Lobstershop Wall for the second dive.

I think this is where I need the most clarification, where did you get at what point you have 1 knot currents? Is this related to the exchange amount?

Also, generally speaking what current levels start to be considered dangerous?

And why 11:45 (about half an hour before slack), is this also based off what point the current speed drops to an acceptable level? Related to level of exchange?

Thanks again, this has been very helpful although I'm still not quite there.

Go to the link I posted and look for Tacoma Narrows South (mid-channel) current. There is a entry on that page that is described that way. Click on that. Enter the date and change the 2 day forecast to 1 day and you will have the same information that I gave you. Then you apply the corrections that you can get from the Northwest Shore Dives book which I provided.

For the tide info that I used look in the same area that you find the description for Tacoma Narrows current and find a description that doesn't have the word current in the description this will be tide information (it sounds like you found this one).

Regarding how large an exchange you want to deal with it depends on your experience level and the dive site. It does mean that the slack period will be less but more importantly it means the penalty will be much greater if you miss slack. Meaning the ramp up to max current will occur more rapidly...as in you may have a very difficult time fighting the current while you're trying to get out.

A dive like Day Island Wall which is well off shore is not one that most people would do on a high exchange day...you might not make it back in! On the very highest exchanges like we have in the summer sometimes most people would not dive any of the current sensitive sites. On more moderate higher exchanges (relative terms I know) you might do Keystone or even Sunrise since you are always close to shore but any current intensive site would be best to limit to no more than moderate exchanges.

In general you might want to get into the water 1/2 hour before slack just for manageable currents on both sides of slack but this is just a general rule. If the currents are wicked on one side (large exchange) and mild on the other side of slack then you might get in just before slack.

As far as how I know the predicted current an hour from slack...you can change the settings on any of the current predicting pages to give predictions in any time limit that you want as in every minute or every 1/2 hour or just the default of slack and max current. I use 30 minutes and locate slack and then see what the current is doing before and after that.

I agree that asking dive shops is hardly the long term answer. It's not even the short term answer in many cases.

[Narkd]

The best advice I can give you about predicting the tides and currents is to take Mischi's course on the subject.

This is absolutely the best advice you have been given. Her Current and Tide Tables book also has a wealth of information for planning dives. You say this isn't covered much in class. Your profile says you are AOW certified with 26 dives. If tides and currents weren't covered much, you either certified somewhere other than Puget Sound or you needed a better instructor. Asking others for dive times is risky business. These are just PREDICTIONS. You really need to be comfortable in checking your own dive times if you are going to lead dives. Most people I know are reluctant to give out dive times to someone they are not familiar with. There are only a few divers I know that I ask about dive times.
Another good idea is to go on some dives organized by the local shops (or clubs) and compare your predictions with the scheduled dive times and the actual conditions. Good luck.

[Graeme]

This is absolutely the best advice you have been given. Her Current and Tide Tables book also has a wealth of information for planning dives.

Is this a member on here? Are they associated with any shop or have a website or whatever?

You say this isn't covered much in class. Your profile says you are AOW certified with 26 dives. If tides and currents weren't covered much, you either certified somewhere other than Puget Sound or you needed a better instructor.

Well AOW doesn't really have any academics. Open Water I think my instructor taught very much by the book. This is probably the norm from what I've heard, but in hindsight I kind of wish I'd tried to find an instructor who added on more about the local environment and went beyond the standard criteria. I can see why some people become very disillusioned with PADI.

Another good idea is to go on some dives organized by the local shops (or clubs) and compare your predictions with the scheduled dive times and the actual conditions. Good luck.

I actually kind of did that the last time (at Titlow actually) and realized that I needed some improvements in my calculations.

[Graeme]

Go to the link I posted and look for Tacoma Narrows South (mid-channel) current. There is a entry on that page that is described that way. Click on that. Enter the date and change the 2 day forecast to 1 day and you will have the same information that I gave you. Then you apply the corrections that you can get from the Northwest Shore Dives book which I provided.

For the tide info that I used look in the same area that you find the description for Tacoma Narrows current and find a description that doesn't have the word current in the description this will be tide information (it sounds like you found this one).

Regarding how large an exchange you want to deal with it depends on your experience level and the dive site. It does mean that the slack period will be less but more importantly it means the penalty will be much greater if you miss slack. Meaning the ramp up to max current will occur more rapidly...as in you may have a very difficult time fighting the current while you're trying to get out.

A dive like Day Island Wall which is well off shore is not one that most people would do on a high exchange day...you might not make it back in! On the very highest exchanges like we have in the summer sometimes most people would not dive any of the current sensitive sites. On more moderate higher exchanges (relative terms I know) you might do Keystone or even Sunrise since you are always close to shore but any current intensive site would be best to limit to no more than moderate exchanges.

In general you might want to get into the water 1/2 hour before slack just for manageable currents on both sides of slack but this is just a general rule. If the currents are wicked on one side (large exchange) and mild on the other side of slack then you might get in just before slack.

As far as how I know the predicted current an hour from slack...you can change the settings on any of the current predicting pages to give predictions in any time limit that you want as in every minute or every 1/2 hour or just the default of slack and max current. I use 30 minutes and locate slack and then see what the current is doing before and after that.

Thanks, I think I'm starting to get this, I never understood the relation between tide tables and current charts before. For some perspective though, how fast is 1 knot? I know people are reluctant to answer this since there are so many variables, but generally speaking what speed would you consider starting to get potentially dangerous for newer divers?

Also, I'm a bit confused why you said you'd have about an hour before it hit 1 knot? Looking at the current chart, there are 2.5 hours between slack and max flood, but max flood is only -1.57 knots. Is the increase in speed not linear or were you just being very rough? Because if it was linear, then the current is increasing about 0.63 knots an hour, so it would be at least an hour and a half before it reached one knot?

I agree that asking dive shops is hardly the long term answer. It's not even the short term answer in many cases.

It's the good text book answer, but not particularly realistic long term.

[BASSMAN]

Keep doing what you are doing. Asking the questions to everyone you dive with, the dive shops and divers on this board.
You keep asking the questions and I'll keep reading.
BTW, 30 min SI at Titlow is very reasonable given the typical depths there.
But I too, ony do one dive there. and then move on to another site.
I like to plan for Day Island and then do Titlow for a second dive after Day Island.
Day Island seems to be a bit tricky to plan. Sometimes I've dove 30 min befor slack and other times 90 min before slack.
I think it depends on wich slack you are planning for, before a flood or before an ebb. I have not figured it out yet.
All I do know is, I have yet to successfully dive the South wall at Day Island. ](*,)

Keith.

[cardiver]

Keep doing what you are doing. Asking the questions to everyone you dive with, the dive shops and divers on this board.
You keep asking the questions and I'll keep reading.
BTW, 30 min SI at Titlow is very reasonable given the typical depths there.
But I too, ony do one dive there. and then move on to another site.
I like to plan for Day Island and then do Titlow for a second dive after Day Island.
Day Island seems to be a bit tricky to plan. Sometimes I've dove 30 min befor slack and other times 90 min before slack.
I think it depends on wich slack you are planning for, before a flood or before an ebb. I have not figured it out yet.
All I do know is, I have yet to successfully dive the South wall at Day Island. ](*,)

Keith.

And don't try two dives at DIW. No matter how enticing it might seem........

[gcbryan]

Thanks, I think I'm starting to get this, I never understood the relation between tide tables and current charts before. For some perspective though, how fast is 1 knot? I know people are reluctant to answer this since there are so many variables, but generally speaking what speed would you consider starting to get potentially dangerous for newer divers?

Also, I'm a bit confused why you said you'd have about an hour before it hit 1 knot? Looking at the current chart, there are 2.5 hours between slack and max flood, but max flood is only -1.57 knots. Is the increase in speed not linear or were you just being very rough? Because if it was linear, then the current is increasing about 0.63 knots an hour, so it would be at least an hour and a half before it reached one knot?
[

I've been in a drift dive at 4 knots. If you turn perpendicular to the current and kick as hard as you can you will make no progress. At 2 knots you can kick and make some progress as in trying to get out. In general you don't want to actually have to kick into much more than 1/2 knot but you can deal with 1 knot. Remember, in most cases when you see a current figure it's still probably a little less where you actually are. I don't plan on being in the water if the prediction is more than a knot at the end of my dive and I plan on it actually being quite a bit less where I am.

To answer your question about where I came up with the numbers...play around with the controls at that site for the current locations. The default is to tell you when slack and max current occur but you can change the settings to tell you what the current is predicted to be for a minute by minute prediction if you want. I set it to :30. That's where I read the numbers I gave to you. It's not a linear thing.

The bottom line is you try to minimize current and deal with whatever you can't eliminate.

One other point regarding current and how it works. In other sections of the country you may notice using this same program that there aren't many current reporting stations...they are mostly tide reporting stations. The difference here is that we are not on the coast...we are 90 miles inland otherwise there wouldn't be much difference between high and low tide and slack. We also have hundreds of miles of inland coast line. It is possible to have slack be as much as an hour apart for sites that are only 1 mile apart. Once you push all that water in Puget Sound it takes a while to get through all the restrictions.

One other point regarding Titlow in case you haven't been there before. There are the pilings straight out from the entry point. These are interesting (I guess) with a lot of stuff growing on them. There is another area way over to the left and out from the building on stilts. If you look out from there you will see some vertical pilings with a horizontal cross member. If you go out there, there are ledges that usually have quite a few GPO. I don't go to Titlow much but when I do that is where I go.

If you have more questions just post. Classes are nice but if you want to dive next Friday they don't do you much good. It's not a difficult subject but it's not one that anyone is born knowing either!

[Narkd]

This is absolutely the best advice you have been given. Her Current and Tide Tables book also has a wealth of information for planning dives.

Is this a member on here? Are they associated with any shop or have a website or whatever?

You say this isn't covered much in class. Your profile says you are AOW certified with 26 dives. If tides and currents weren't covered much, you either certified somewhere other than Puget Sound or you needed a better instructor.

Well AOW doesn't really have any academics. Open Water I think my instructor taught very much by the book. This is probably the norm from what I've heard, but in hindsight I kind of wish I'd tried to find an instructor who added on more about the local environment and went beyond the standard criteria. I can see why some people become very disillusioned with PADI.

Another good idea is to go on some dives organized by the local shops (or clubs) and compare your predictions with the scheduled dive times and the actual conditions. Good luck.

I actually kind of did that the last time (at Titlow actually) and realized that I needed some improvements in my calculations.

Mischi can be found at http://www.pelagiascuba.com . A GOOD AOW does have some academics. It is easy to "become very disillusioned with PADI" but there are PADI instructors who do teach at a higher level than "the book" just like there are SSI instructors that worry more about their ego than their students learning, and so on. It isn't the agency, it IS the instructor. Your hindsight will serve you well moving forward with your diving. There is a good thread about interviewing instructors...dig around and read it. Your already have some good questions to ask based on your experiences. You are now starting to learn. I'd suggest finding an really respected and knowledgeable instructor for a Tides/Currents/Drift Diving specialty. I always think of a martial art parallel...I wouldn't want to take martial arts from a black belt, I would seek out the true master. Go forth, Grasshopper...

[Graeme]

Mischi can be found at http://www.pelagiascuba.com . A GOOD AOW does have some academics.

Alright thanks, I'll watch the site. All AOW has some academics, but mine was largely just rehashing the book and going over the answers to the basic questions. Nothing really about currents (at least nothing useful).

It is easy to "become very disillusioned with PADI" but there are PADI instructors who do teach at a higher level than "the book" just like there are SSI instructors that worry more about their ego than their students learning, and so on. It isn't the agency, it IS the instructor.

Right, but you're basically saying that in order for an instructor to be good they need to ignore the agency (not as in ignore the standards, but ignore what the agencies tells them is an appropriate amount of material). This says to me there is a problem with the agency. Additionally, while I don't have personal experience with them, agencies like GUE and UTD have tougher curriculums and keep close tabs on all instructors so a good couse is less about the instructor.

our hindsight will serve you well moving forward with your diving. There is a good thread about interviewing instructors...dig around and read it. Your already have some good questions to ask based on your experiences. You are now starting to learn. I'd suggest finding an really respected and knowledgeable instructor for a Tides/Currents/Drift Diving specialty. I always think of a martial art parallel...I wouldn't want to take martial arts from a black belt, I would seek out the true master. Go forth, Grasshopper...

haha ya I think I'm getting smarter (reading online is a huge help) and won't go into classes anymore without some familiarity with the instructor.

[Graeme]

I've been in a drift dive at 4 knots. If you turn perpendicular to the current and kick as hard as you can you will make no progress. At 2 knots you can kick and make some progress as in trying to get out. In general you don't want to actually have to kick into much more than 1/2 knot but you can deal with 1 knot. Remember, in most cases when you see a current figure it's still probably a little less where you actually are. I don't plan on being in the water if the prediction is more than a knot at the end of my dive and I plan on it actually being quite a bit less where I am.

Thanks, that is very helpful

To answer your question about where I came up with the numbers...play around with the controls at that site for the current locations. The default is to tell you when slack and max current occur but you can change the settings to tell you what the current is predicted to be for a minute by minute prediction if you want. I set it to :30. That's where I read the numbers I gave to you. It's not a linear thing.

Ah I didn't see all the options you could set. So when I look at the currents at 5 minute intervals, it looks like roughly 11:15 - 12:30 are the 'safe' diving times, but you need to add the correction to that, so you get about 11:45 - 1:00?

It also looks like late afternoon has a slower exchange, and if you were comfortable diving anything less than 1 knot you could go right from 4 until 6:30? Is this correct?

One other point regarding current and how it works. In other sections of the country you may notice using this same program that there aren't many current reporting stations...they are mostly tide reporting stations. The difference here is that we are not on the coast...we are 90 miles inland otherwise there wouldn't be much difference between high and low tide and slack. We also have hundreds of miles of inland coast line. It is possible to have slack be as much as an hour apart for sites that are only 1 mile apart. Once you push all that water in Puget Sound it takes a while to get through all the restrictions.

I had no idea about that, that's interesting.

One other point regarding Titlow in case you haven't been there before. There are the pilings straight out from the entry point. These are interesting (I guess) with a lot of stuff growing on them. There is another area way over to the left and out from the building on stilts. If you look out from there you will see some vertical pilings with a horizontal cross member. If you go out there, there are ledges that usually have quite a few GPO. I don't go to Titlow much but when I do that is where I go.

If you have more questions just post. Classes are nice but if you want to dive next Friday they don't do you much good. It's not a difficult subject but it's not one that anyone is born knowing either!

I actually have been to Titlow but have never gone out towards the bottle field area, hopefully I can sometime when I'm with someone who knows where it is. And I'm not actually planning to go out Friday (I actually have work) it was just an example to use.

One kind of random question though, I've heard from someone that at one point they needed to use knives to get back at Edmonds Park? This site isn't one I've heard of for being current sensitive and had no issues when I went there. Could this actually be possible?

[gcbryan]

I'll just add classes are good and are one way but not the only way. I'm pretty sure (not positive) that Mischi learned this on her own as did I.

Bob Bailey teaches an excellent class in gas management but I believe he learned it they way I did...through reading on the internet, diving and talking with more experienced divers.

Regarding your comments it sounds like you have it figured out now.

Having to use a knife at Edmonds...yes, anything is possible. It does get some current on higher exchange days. I can't say I've ever been there where I would need to use a knife to crawl back in. That depends more on how well you know how to handle current though. You never (rarely) really have to use a knife to get out of current as in ...there are better ways however I have been in current where you could have used that approach. It's not a reason to go out and buy a big jungle knife however.

Basically places like Edmonds, the Junkyard, Mukilteo City Park do get some current but the beach is so long that getting out isn't nearly the problem you have when the exit area is limited and you are in current. The latter two dive sites do get more current than Edmonds however.

[Graeme]

I'll just add classes are good and are one way but not the only way. I'm pretty sure (not positive) that Mischi learned this on her own as did I.

Bob Bailey teaches an excellent class in gas management but I believe he learned it they way I did...through reading on the internet, diving and talking with more experienced divers.

Regarding your comments it sounds like you have it figured out now.

Having to use a knife at Edmonds...yes, anything is possible. It does get some current on higher exchange days. I can't say I've ever been there where I would need to use a knife to crawl back in. That depends more on how well you know how to handle current though. You never (rarely) really have to use a knife to get out of current as in ...there are better ways however I have been in current where you could have used that approach. It's not a reason to go out and buy a big jungle knife however.

Basically places like Edmonds, the Junkyard, Mukilteo City Park do get some current but the beach is so long that getting out isn't nearly the problem you have when the exit area is limited and you are in current. The latter two dive sites do get more current than Edmonds however.

Great, thanks. I think I understand everything except for the "correction" which I'll need to see the NW Shore Dives book before I know if it makes sense or not.

The reason I originally asked for a step by step example of what you'd do is it made it way easier to clarify what I didn't understand and test myself when working through an actual example. And in the end I think that worked.

I guess with Edmonds or similar spots it never hurts to check beforehand what the currents will be like.

[gcbryan]

I guess with Edmonds or similar spots it never hurts to check beforehand what the currents will be like.

It never hurts to know when slack is. It never hurts to know when high tide is either. At shallow sites in particular the visibility can be better at the higher tides and if it's a really shallow site very low tides may be difficult to deal with...tripping over stubs of pilings that are usually underwater and not being able to get away from the kelp or whatever.

There's a booklet issued yearly available at most dive stores called "Tidelog" that most divers have even keep in the car in many cases. It's a quick graphic way of looking at tides (and currents) for a particular day so when you're thinking about diving next week for example you can quickly look at the graphic and see whether you should be planning on a non-current sensitive site or whether another site would be possible. That and the North West Shore Dives book are all you need.

For each site in the book it will have corrections to the nearest current reporting station for that particular site and the corrections will be for slack before ebb and slack before flood. You may for example have :30 minutes to add as a correction before one slack and :05 to subtract for the other.

It's pretty self-explanatory when you have the book to look at. The first chapter in the book (before all the site reviews) also talks a bit about dive planning.

Finally, since we've been fairly complete with this thread and others may review it at a later time...slack before ebb is the slack that is occurring in the high tide range and slack before flood is the slack occurring in the low tide range.

If you were close to the coast flood would mean the water is flooding into the strait of Juan de Fuca and ebb would be when it's flowing out. However, once you get inland you need to read in the book which ebb or flood moves which way at that particular site. In other words water flowing into the beach you are at isn't necessarily a flood. At Skyline Marina Wall ebb is when the current is flowing back to the beach so you know that just by reading the book or looking at a chart to see how it affects a particular spot rather than just thinking about in or out.

Buy the book and the TideLog for this year and you're good to go for most any site in Washington (saltwater shore dive that is).