If you’re not already a reader of Barge Hawthorn’s blog, may I suggest that you start now? The account of the descent into Dublin along the Royal Canal, over three days, features mounting tension, a really superb photo of the M50 aqueduct and a happy ending when Effin Bridge lifted when required.
You can work your way backwards through earlier posts to find the how and the why.
Irish waterways history 
quite how casual tourist hirers could cope with all this, I really do not know! “Cruising ring, my arse”, one might contend…..
Nonsense, my dear chap. Where’s your spirit of adventure? True canal-goers like that sort of thing and rarely travel without angle-grinders, large poles, bolt-cutters, wetsuits and welding gear. bjg