Course To Steer Calculator - Volunteers to test required

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SimonFa

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Some people while away the horrible winter days doing jigsaws, reading, making matchstick models of Parliament or any number of hobbies. Me, I've been trying to keep the brain active by learning JavaScript and writing a webpage that does course to steer calculations to replace a spreadsheet I'd done when I was on my theory course.

I think it might be useful to everyone, especially novices, so I'm making it public but before it gets too widely publicised I'd appreciate some testing and feedback from experience sailors. I have tested the maths a few times and am fairly confident, but with these things its easy to convince yourself you're right so some bashing away at the calculations would be really appreciated.

It might not seem user friendly at first because, as I say in the help page, I've tried to de-clutter the screen and used toooltips for help because once you've used it a couple of times it should be straight forward, even for a novice sailor.

I know its always tempting to click straight through warning screen so if you do please take a few minutes to read the about, help and bugs pages.

Thanks in advance,

Simon

http://cts.fawthrop.me.uk/
 
Nothing wrong with the theory but I wonder about the practicality. Its very similar to my hand crafted method using a tides proforma, it takes the drudgery out of the vector sums that I generally guess at. Its the precision that bothers me, I tried it on a cross channel Needles - Cherbourg trip. Though I put in 6 knots I know thats going to vary, I may not be able to sail the course anyway and I generally check position halfway over and recalc if necessary.

Where it would really score would be the ability to transfer tidal data from the ReevesFowkes pages into the spreadsheet :) cos thats the really laborious bit. So, would I use it ? probably not - sorry

Edit: Also notice that the Predicted Passage plot doesnt scale with the 12 mile set to the E that my numbers created. Using FireFox on Windows
 
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Sorry to be negative but I already have that on board at no extra cost. I enter a waypoint on my gps, press goto, press Track on my autopilot and sit back. It then takes me direct to the waypoint adjusting the steering to keep on the great circle course to within 0.01 of a mile.
 
snowleopard said:
Sorry to be negative but I already have that on board at no extra cost. I enter a waypoint on my gps, press goto, press Track on my autopilot and sit back. It then takes me direct to the waypoint adjusting the steering to keep on the great circle course to within 0.01 of a mile.
Click to expand...

And on a cross tide trip you'd watch all the other boats enter harbour before you whilst you first fought the tide one way then fought it back the other while they did the shortest course through the water. But if boat is fast and tides are light then the difference is much smaller than when I used to cross to Chanel du Four in a 24 footer.
 
RupertW said:
And on a cross tide trip you'd watch all the other boats enter harbour before you whilst you first fought the tide one way then fought it back the other while they did the shortest course through the water. But if boat is fast and tides are light then the difference is much smaller than when I used to cross to Chanel du Four in a 24 footer.
Click to expand...

If you have a slow boat and the trip takes more than one tide or if you are racing it would make a difference. With a cruising average of 7 knots, I'm not bothered.
 
I admire the effort and ingenuity involved, in fact, I wrote a spreadsheet ( not half as smooth looking though and without the plotting) to do the same sort of thing when I was doing my RYA courses.

But with so many free (or very cheap) apps that do the same thing, often adding in wind angles and polars as well, are you not re-inventing the wheel?
 
I found paper and a pencil faster. A few of the passages I make are not straight lines, e.g. Exe - Alderney and there is a small issue of the TSS in the way so that needs to be calculated for.
 
I tried on an IPad (safari) and an android (chrome) tablet and both machines crashed when I went to enter the tide direction data (the webpage would not respond and I had to close the browser to get back out)

How are you supposed to populate the tidal stream data ? By measuring the streams off of a tidal atlas? Don't you need to know where your position is to find the stream at that location? If you do need to know your position it would be good to see something like an XTE on the table as a guide as to where to look.

good luck
 
Thanks everyone who's taken the time to have a go. I haven't responded earlier because I've aggravate a long standing back problem which left me on my back and only able to read from my iPad and make the odd short comment.

I haven't been able to make it crash but obviously something is wrong and I'll have a god look at the code and see if I can replicate it.

In answer to some of the questions, I know there's other apps out there but this was project to help me get to grips with JavaScript and other computing coding issues I wanted to understand rather than trying to solve a problem.

As I said in the OP, its not much more than a spreadsheet and at this stage it does require the user to have the ability to be able to read their own tidal stream data and carry out interpolation if it isn't neaps or springs. I don't think it will ever be able to read in that data, not least because it costs money and this is a hobby not a commercial product.

I'll let you know if I ever find the bug that's causing it to crash.
 
for info I have been using: 09:55,22:54 HW Times, 180T, 5kn,60NM, 09:55 depart. and trying to put 0.02kn @ 270 deg in tide table 0955 entry. I haven't been able to move away from the 270 direction entry
 
Feature request: What I tried to do a little while ago then gave up due to LOI was to get the lat and long of each node of the passage. Then they could be plugged into the plotter & perhaps the autopilot so that I could see if I was getting more or less leeway etc than I had allowed for or to automatically compensate for the leeway
 
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