Originally Posted by
BigEndBob
Would be interesting experiment to suspend a spoon inside a large glass vacuum flask, then play water over back of spoon then see what happens?
Think no one theory explains lift, they all do.
I also noted one day a good example of the venturi effect whilst standing next to a canal near a bridge.
The canal narrows to pass under bridge and leaves floating on the surface speeded up as they passed under the bridge and slowed down on the other side as the canal widened.
Also the QEII had a problem some years back where it travelled fast off the US coast and scrapped its bottom in shallow sea.
Theory was that the bottom got sucked down and hit some rocks that it should have easily sailed past.
I wrote a paper on Shallow Water Shiphandling when I was on the staff of the Royal Navy Navigation school in the late 80's - I can't remember all the formulae now but there was a rule of thumb which (I think) suggested squat was a risk when depth < 1.4x ship's draught. Also built some reasonably complex spreadsheets to predict the actual amount of squat vs depth for different classes of ship, based on hull form. Funnily enough, this was only a few months before the QE2 incident.
Interaction between ships due to increased pressures at some points and reduced at others has caused quite a few accidents over the years - we always had to be wary of it conducting Replenishment at Sea operations, when ships approached each other and then steamed alongside.