: I would like to install some adjustable footrest/pedals in
: my night heron like these.

have a look at -

http://home.clear.net.nz/pages/grantglazer/Kayak/Hints.htm

And go to the page with rudder pedals. The pedals run on a track fitted to the bottom of the kayak, held in by a bar retainer (piece of wood with a slot in it) at the fore end and a nylon bolt epoxied in at the aft end of the bar. Note the way the rudder lines go - they are "auto-adjusting". The only adjustment is by the webbing strap holding the pedal platform.

If you need more pictures, let me know - I'm just finishing off the latest kayak and making a set of pedals for my partner for her latest build.

Alex