Monday, October 06, 2008

Canal easycalc mark1

For some time now I've been using spreadsheets to work out how long it will take to get from one place to another when we're cruising. I get my distance data from the wonderful Canalplan site, import it into Excel and manipulate it to give times in hours and minutes to get to any place from the start (typically our home base). The finished sheets look a bit like this.
Kath complains that you have to subtract one time from another to get the time between intermediate points, so I started thinking about something simpler to use. So here is mark one of my canal easycalc disc.

This one is for a trip from our base at High Line Yachting (HLY) in Iver, to Paddington basin - about five and three quarter hours usually. I picked this one because there are no locks to make it simpler.

The outer pink ring shows elapsed time in hours and the inner yellow disc, which is free to rotate shows places along the way. I worked out the angle for each place in 360ths of the whole journey time , then just used a protractor to draw them on.

So looking at the first picture you can see it takes about one and three quarter hours from the start to get to Bulls Bridge. Easy. Now the really cool bit comes next. By rotating the yellow disc, I can easily see that it will take two hours to get to Kensal Green when I am at the Back Horse. Neat.

The idea is to make a set of these discs for typical journeys we take e.g from Iver to Marsworth. This particular version uses the whole journey time to make up the 360 degrees, but next time I might just make a 6 hour outer disc (or a 6 day outer disc or whatever), without necessarily taking up all the circle on the total distance. (If you get my drift - don't worry if not :-) )

What do you think?


Halfie said...

I like it! I'd say: yes, definitely have a fixed "standard" outer disc, so "all" you have to make for each trip would be the inner disc. Twelve hours would seem to be an obvious choice, to mimic a clock face, but that would possibly leave you with awkward overlap problems for a long cruise. Perhaps 24 hours would be better. Then I suppose when making up the inner discs you could give an hour or two overlap. Of course, with a standard outer disc the conversion from time to degrees is simpler: 30 degrees/hour for the 12 hr disc; 15 degrees/hour for the 24 hr disc. And you could keep your Excel programme, adding a column for it to work out the number of degrees for you. Perhaps the ultimate would be to plug it all into a pie chart programme which would give you the discs simply to print off!

VallyP said...

Very clever indeed ;-)

Anonymous said...

Now all you need to do is work with Nick and get CanalPlan to offer your clocks as an optional output !