Just remembered that our recent two-week trip along the Trent & Mersey, Macclesfield and Peak Forest was memorable for the absence of one of those annoying events - a trip down the weed hatch to clear the propeller. These events can sometimes happen on canals that appear quite clean but they are perhaps more common where water is shallow and of course are common in urban areas.
Given the environs of Stoke and the renown shallow nature of the Macclesfield & Upper Peak Forest canals, I was waiting most days for the dreaded signs of "stuff" around the prop - lack of progress and black smoke from our Ruston. I did on a couple of occasions experience what must have been some build up of vegetation around the prop at the notoriously tight bridge holes on the Macclesfield, but this was easily cleared by a short burst of reverse.
We must of either been lucky or perhaps the steady stream of boats using the route had cleared the way - summer boating.
I expect that now I have posted about it the next time we leave the marina we will probably pick up something very nasty! Am I chancing my arm mentioning it?