RickB's avatar photo
I'm not sure if RickB's creative avatar photo is implying a "manual" bow thruster or a way to propel the boat.* But it reminds me of a somewhat similar technique that was widely used on the canals in England.
The canals occasionally run through tunnels, some of which are quite long, like the famous Harecastle Tunnel*which is*1.6*miles long and the recently re-opened*Standedge Tunnel which is 3.1* miles long.* And there are many shorter tunnels, ranging from 30 or 40 yards to a quarter mile or more.
Until the very late 1800s the narrowboats were pulled by horses.* But canal construction including tunnel construction was totally manual labor in the late 1700s and early 1800s when the bulk of the British canals and their aqueducts over rivers*and tunnels under hills*were built.* So making a tunnel wide enough for a towpath was economically out of the question.
So the boats, most of them 70' long and 6-1/2 feet wide, were propelled through the tunnels by professional "leggers,' men who lay on top of the loads in the holds of the narrowboats and "walked" along the walls of the tunnel.* While they did this, the horse was led over the top of the hill to the tunnel portal on the other side.
Steam tugs that hauled strings of narrowboats through the tunnels*and later self-powered narrowboats made the practice of legging obsolete.* But I found this photo of some guys legging a narrowboat through the Standedge Tunnel on the web.
We've been through the Harecastle Tunnel many times with a diesel-powered narrowboat and it takes about 45 minutes. It took nearly three times that to leg a boat through.* The second photo shows the northern entrance to the Harecastle.* The original tunnel is to the right.* For awhile both tunnels were used, one for northbound traffic and one for southbound.* Eventually subsidence caused the closure of the original tunnel.* The mouths, like the edges of bridges, are painted white for visibility at night.* The water is red because of the extremely*high iron content in the hill the tunnel goes under.
So if RickB could cut*a few more sets of*holes in the bottom of the boat he's in and gather a bunch more guys, they could propel the craft along in shallow water like a centipede.* The breathing thing would have to be sorted out, though.
-- Edited by Marin on Tuesday 13th of July 2010 05:55:56 PM