Bob Wood wrote: > 2008/7/17 Brian J Goggin [EMAIL PROTECTED]: > >> "Having reached the highest level of the great table-land, we >> traversed a space of fifteen miles without a lock; and here a curious >> phenomenon, illustrating the incompressibility of water, arrested our >> attention. About every twenty or thirty minutes, the horses are >> obliged to stop for five or six minutes, to take breath, the cause of >> which was this: --- The velocity of the boat impelled the water with >> such force that it gradually rose so as to approach the summits of >> the banks, when it began to recoil, so as actually to form a >> back-water or stream, when the horses were unable to make head, and >> therefore stopped until the equilibrium of the canal was restored." >> >> I have not heard of that phenomenon before. Has anyone else come >> across it? > > > I think everybody who has tried to go too fast along a narrow and > shallow canal has suffered from this effect.
A 30ton boat that has moved one boat length (70ft) has displaced 30 tons of water - that either goes around and under the boat, or is pushed forwards - the ratio of which depends on the available "gap" between the boat and the canal sides/bottom. We've all experienced the difference between shallow and deep canals - I remember coming out of Kingswood Junction many years ago (into the GU) and we felt the back of the boat sink slightly and the speed went right up as we came into deep water. Ron Jones Process Safety & Development Specialist Don't repeat history, unreported chemical lab/plant near misses at http://www.crhf.org.uk Only two things are certain: The universe and human stupidity; and I'm not certain about the universe. ~ Albert Einstein
