The recent collision between two oil tankers off the South Coast of Britain has focused attention on the steering and braking problems of these mammoth vessels.
LV (voice over) Model tanker in water
CU Technician watches as model goes astern (2 shots)
SV and CU Superintendent of Shipping Division faces reporter
CU Superintendent speaks, using hands to demonstrate rudder
CU and SV voice over, model rotates in own length
SV and CU another model
CU hand points out hole in bows
CU hole in aft of model
CU technician with model
CU Superintendent speaking
SV voice over, shots of model tankers manoeuvring
TRANSCRIPT: REPORTER: "With a conventional rudder big tankers are hard to manoeuvre at the best of times. At slow speeds manoeuvrability is even worse and if the ship is going astern the rudder is useless. But the rudder being used on these 12 - foot models at the National Physical Laboratory offers some dramatic improvements. It is explained by the Superintendent of the Shipping Division, James Parfit."
PARFIT: "This is a rudder, it looks very much like the ordinary ship's rudder. This is the leading edge, trailing edge. The propellor would normally be rotating here. Now, your ordinary ship's rudder you can turn over to about 30 degrees and then it stalls. It's like an aeroplane's wing - it loses lift - and it's no good going beyond 30 degrees because you get no force out of it. But by quite a simple modification - this is a quite well-understood principle that's been in the literature for many years - by a simple modification to this rudder you can replace the leading edge by a rotating cylinder. It may not be obvious to the camera but this portion here rotates, it goes round. We can twiddle it with this shaft up here. And if you do that at the necessary speed, your rudder can be turned through 30 degrees, 40 or 50, in fact in some version up to 90 degrees, and you are still getting a very big sideways force from this rudder. And we've shown with ship's models that a ship fitted with this kind of rudder can turn literally in her own length."
REPORTER: "The Laboratory is also developing a more effective braking system for tankers which involves taking in water through the bulbous bow of the ship and letting it out further up, thus slowing the ship down much more quickly. Important developments - but have they yet been tried out on a full-size ship?"
PARFIT: "No, we haven't but we live in hopes. What we really want is a shipowner with the faith and the money to say 'Here's a real ship, try it out; if it fails well that's just too bad'. Bright ideas, we say around here, bright ideas are ten a penny. It's very easy to produce a whole range of inventions which will work on this model scale but which for one reason or another fall by the wayside as you are getting to the full-scale. You don't have materials strong enough, pumps with big enough capacity, you can't afford the money - the big trouble I think in this country is not making inventions in the first place, but in conveying whose inventions right through to the full-scale ironmongery."
Script is copyright Reuters Limited. All rights reserved
Background: The recent collision between two oil tankers off the South Coast of Britain has focused attention on the steering and braking problems of these mammoth vessels.
Experiments being conducted at Britain's National Physical laboratory with new rudder and braking systems give hope of important future developments which could reduce the danger of further accidents.