Hi,
I'm new to boating and have just bought a 55ft narrowboat with 35hp Lister Petter engine. On my maiden voyage from Braunston to Napton I found the boat was cruised smoothly at around 3-4 mph at 650 revs with very little prop wash. However at times she slowed and as I applied power to 1000 rpm there was no noticeable increase in speed but a great deal of prop wash, and increased noise. I've read a bit about shallow water affecting boats but I thought that was larger vessels but just thought I'd ask if this Is a natural effect of varying water depth in the canals.
Martin