That looks terrific Glen - great job!! Mine is now ready for varnishing, then I'll do the final bits (anti-slip tape on upright, rubber on the seat & Velcro strap). I've made a few extra mods to mine:
a. I've used 3/8" t-nuts & bolts instead of 'lag screws' to anchor the bottom support beams to the uprights - it allows me to remove the support beams for storage/transport of the chair. Not sure of t-nut's longevity since they're 'liquid nailed' into place ... will see how that pans out;
b. I've made a support beam for the rear upright in addition to the front support beam to help make the chair more stable;
c. I've made the uprights 42" long instead of 32" to give me more reach for my 14" dob;
d. Extra screws here & there to improve the rigidity of the seat.
I've also bought a small cushion to put on the seat to delay the onset of a numb bum
If I had to do this again, I wouldn't use pine decking timber - it's cheap and looks good when sanded but was a pain to make it look ok. Further, I'd buy only just enough materials; I seem to have plenty left over! Alex