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 Post subject: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 8:32 pm 
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Okay, this is a topic towards all of you tech minded individuals out there or school owners.

I need to come up with a faster way to creating my lesson schedules that are based around the changing tides. Due to the huge tidal changes in my area, I am forced to schedule most of our lessons within a 4-5 hour window around low tide. If you can imagine, this can be very time consuming when you are trying to plan out an entire season around this since everything is constantly changing. I know this seems like it would be pretty basic seeing as the tides are typically changing every 6 hours and move back about 50 minutes everyday but, overtime it will get messed up because the it isn't always exactly 50 minutes etc.

At the same time, I also plan out paddleboarding tours around the tides. Certain tours only work an hour before slack tide or a changing tide. We have extremely strong currents in the rivers that we give tours on and it is very difficult to teach a beginner paddleboarder to fight the currents while they are still learning to use their paddle and stand on their board.

I already understand how to create our schedule around this but I am looking for a faster and more efficient way of doing this. Any ideas, suggestions or comments would be greatly appreciated. If you need more info, i can share that as well.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 8:55 pm 
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try

http://www.tides4fishing.com/

select your area and the closest reference point, then you can customise it at the bottom of the site.

i think the monthly overview at the end is what you are looking for.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 9:07 pm 
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I do a lot of mathematical modeling. I would think if you can pull the data and clearly identify your constraints then this could be done in a simple spreadsheet model. I can probably help build something simple for you. That is if you can get the data.

1. I do not know where you are located, but in the US there are a lot of free sources to pull tide data and paid sources to get more detailed data. So for free I can usually get a month of tides for a specific location, with times, height, and sunrise sunset.

D
Quote:
ay High Tide Height Sunrise Moon Time % Moon
/Low Time Feet Sunset Visible

Sa 1 Low 3:07 AM 0.0 7:02 AM Rise 7:56 AM 1
1 High 8:40 AM 1.3 5:29 PM Set 7:55 PM
1 Low 3:48 PM -0.1
1 High 9:15 PM 1.2


2. What is important to note is that not all tides are the same, the more full the moon is the more extreme the tide changes are. So in my opinion the length of your working period changes. You would need to identify at what point it is too deep or shallow to refine you model.

3. What are your other constraints?
How short can a lessen be
What are your working hours
Prior to closing when is the last lesson
How many concurrent lessons
... other limitations

If I was doing this I would download tide data and build a spread sheet model with some VBA to show possible blocks. Then have the ability to grab an available block and fill it in with assignment.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 9:09 pm 
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Also if you can describe how you do it manually, that will help understanding your constraints and how to automate it.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 9:34 pm 
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Thanks for the great response.

So here is how i've been doing it now.

I find a tide table just like you've suggested. It is typically free and very easy to find. It normally states the sunrise and sunset. I then consider the fact that our lessons don't begin before 9:00 am and must end near sunset. So between those times, i find the low tide and make a five hour block of time. One instructor can have (2) two hour lessons within that time or (1) 4 hour lesson within that time. We don't book more than 4 hours of lessons. I will manually go into my calendar and create these "blocks" for future scheduling. The depth of the water will of course change based around the moon schedule but we don't really need to mark that as a detail of concern. We are mainly concern because the waters stay shallow enough 2 or 3 hours after high tide anyways (typically).

For paddleboarding, we have a couple different tours that we schedule about 30 minutes prior to slack tide whether it be a low or a high. This way, we can either go out of a river with the tide and back with the tide or as little current as possible. For this, I just look at a tide schedule and mark out the times where this works each day based around low tide and high tide as well as if it falls between 9am and an hour before sunset .

I have heard of someone using a spreadsheet of some sort to do this but i'm not sure where i would begin. I'm not really familiar with using formulas etc. Right now, i use an online scheduling program called "supersaas" . It is very time consuming to have to enter each individual time slot for each day.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Sun Jan 26, 2014 10:15 pm 
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Are you tied to SuperSaas? Are you doing a lot of other scheduling on it? Are you using the free version or paid? The reason I ask is that from what I just read there may be some ways to automate it, by synching with external sources. I just do not know enough about it.
If you have MS Outlook or Windows Live Mail (which have calendars) it may be easier to manipulate them. Do you have either of these. If you have MS Outlook it will be very easy to do this in VBA. Another option may be to use a Google Calendar, because they expose an API to allow you to manipulate it. SuperSaas does also
http://www.supersaas.com/tutorials/api, but may be limited to read only.
Can you provide a link to your tide data. I am going to try some techniques if I get a chance. I would probably build a small application stand alone application in .Net to see if I can pull the data, determine the teachable blocks, and push these to some type of calendar (local and web based).


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 Post subject: Re: Scheduling Around Tides
PostPosted: Mon Jan 27, 2014 12:52 am 
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Location: Labia
i use Jtides and has a nice graphic that you can easily see tide heights and times for my general areas
Found it very useful, world-wide, tidal prediction programme: JTide. Written in JavaScript it will run on any computer.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Mon Jan 27, 2014 7:00 am 
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Not necessarily an answer to your question, while we are on the subject of tides...

This is a good rule of thumb when gauging the strength of a tide at a given time. I used it when commercial fishing in an area that had up to 25ft tides.

Example
If a flood or ebb tide is ~6 hours
The tide is rising 18ft ( I know the rest of you are metric, but it will have to do :) )

1st hour = 1/12th of the total movement of the tide which = 1.5 feet
2nd hour = 2/12ths of the total movement of the tide which = 3 feet
3rd hour = 3/12ths of the total movement of the tide which = 4.5 feet
4th hour = 3/12ths of the total movement of the tide which = 4.5 feet
5th hour = 2/12ths of the total movement of the tide which = 3 feet
6th hour = 1/12th of the total movement of the tide which = 1.5 feet

Not all tides are 6 hours so you just take the know tide time length divided by 6 even periods of time. if you have a 7.5 hour tide you would have 6 time periods of 1 hour and 15 minutes each. The water movement would happen in the first 1 hour and 15 minutes and the last 1 hour and 15 minutes would be 1/12th each (of the total flood or ebb tide)

Note that 1/2 of the tide moves in the middle 2 periods of a tide.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Mon Jan 27, 2014 8:09 am 
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I have done exactly as SSK suggests. I have written an Excel program that uses drop down lists to display the tide graphically. You can use bars or limit lines to define the windows of opportunity.

https://db.tt/XSp8y3ip

The first two tabs are the important ones. Tab 1 is the display, Tab 2 is a sheet with the drop down list.
Tabs 3, 4, and 5 are the workings of the program. You can hide them, if you wish. You would have to populate the sheet tabbed "Tidetable" with data relevant to your area.

This is a stripped down version of a program I had written about 15 years ago. The full program has hyperlinks that generate windmaps for my area (Durban), using data from the NOAA servers. If anybody is interested, I can upload that one as well.


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 Post subject: Re: Scheduling Around Tides
PostPosted: Tue Jan 28, 2014 4:15 pm 
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Joined: Thu Aug 30, 2012 2:04 am
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ZigZag,
Can you provide a link to your program. I get an error on that link. Are you able to connect directly to a NOAA database to pull tide data? Interested in how to do that. Like to see your full model. I have been playing with the Google Calendar APIs and have built a small program in .Net that can push the tide information and teachable blocks to a Google Calendar. But now I have to do an import of the tide data manually first. I am a hobbyist programmer, not a real programmer so this is a learning experience.

Mcampa20,
Could you use a Google Calendar instead? I think I can do this with Google since there is a lot of information on using the API. Not sure about the SS program.


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