--- In [email protected], "Phil & Anne Irons" <ve1...@...> wrote: > > On Thu, Dec 31, 2009 at 10:35 AM, John, <j...@...> wrote: > > > >SNIP< > > > > On no thanks - it was only a sort of generalised 'I wonder' with respect to > > the topic under discussion, I don't have a boat so have nothing but a > > moderate interest in the topic. We do from time to time on Sky TV repeats > > see an ice breaker at work on the St Lawrence which has the capability of > > blowing vast jets of air up it's sides to further assist the break up of ice > > but I doubt that that is relevant to narrowboats! Many thanks for your > > interest and all the best for the New Year to you. > > John > > > > > When the ship is under way, the plumes of spray you see flying up the sides > of the ship are mostly from pieces of ice fracturing under great pressure. > Pneumatic 'bubbler' systems are used mainly to keep ice from forming around > the hulls of moored vessels--these are the Great Lakes carriers, which are > nothing more than narrow boats writ LARGE. The ones seen on Lake Ontario > and the St. Lawrence Seaway are 730 ft long--those on the upper lakes (above > Lake Ontario) are up to 1000 ft. long and their passage is restricted by the > size of the Welland Canal locks. Sound familiar? > > Bubbler systems are used on icebreakers too, to assist in breaking the > friction between the hull and the pieces of ice alongside. If you recall in > Laurence's video, narrowboat crews were seen rocking their boats from side > to side; this also breaks the friction, and is accomplished on large > icebreakers by pumping fairly large quantities of water ballast from one > side of the ship to the other. On smaller icebreakers, which also service > floating aids to navigation during the summer, the inclining of the vessel > is accomplished by swinging one or two buoy anchors on the vessel's derrick. > The anchors used are usually in the 3 to five ton range. > > cheers, > > Phil & Anne Irons > nb pedantic > Sydney, Nova Scotia > > > [Non-text portions of this message have been removed]
The information was most interesting Phil. I can't see how this could be achieved on a Narrowboat over here, unless you had a willing crew, (Suitably dressed for cold weather), standing on the gunwales and rocking the boat from side to side! Down in the West of England this Monday morning (08:30am) Somerset, the temperature is an unusual low at -6.5c. I wouldn't be surprised if your weather is slightly warmer, from the information you gave me the other day! Regards ~Allan~ >
