Have recently purchased Navonics, all UK and Ireland, 20euro for my Nokia N8. Good value as East coast Ireland cost 130euro 5 years ago for my laptop.
Charts have good detail and appear up to date. The GPS function on the phone works intermittently
and I haven't figured out the problem yet.
Was heading into port in the dark recently, harbour light out all summer, and was able to double check position on the plotter function. Was spot on.
I also have Wind Guru but without the direction arrows?, UKHO Easy Tide and our local met service set up.
A very useful sit here is In Your Footsteps(lite for phones), great entry, facility and why visit detail on all Irish harbours.