Monthly Archives: February 2014

The Tide

Something that was unexpectedly difficult for me was calculating the state of the tide as a percentage so I decided to post what I came up with in-case someone needs it.

It takes one of the day’s high tide times and the time you wish to know the percentage of, both in hours.

public function get_level($high, $time){
    return cos(pi()/6.2103 * ($time - $high)) * 50 + 50;


The 3 new self priming pumps were the first to arrive, the ones I ordered cost £7.12 each, have a max current of 1.2A at 12V which is less than the old pumps, hopefully without a significant loss of ability to move water. One thing that I wasn’t sure about was if the the pumps already incorporate a one way valve to prevent water flowing backwards though them but after testing I found that it would be necessary so I’ve ordered some.


The second thing was the new relay array for controlling the 12V supply for the solenoid valves and pumps which tidies things up and reduces the amount of soldering. The pressure sensors will be part of a separate circuit board.

Along with the valves I’ve also ordered some more 6mm PVC tubing. With the time for orders to arrive and without any hard deadlines and the inevitable flexibility of self imposed deadlines progress is slow but I’m hopeful it’ll be functional fairly soon.