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The intricate launching calculations had been worked out by a computer – a week’s work reduced to 30 minutes compared with the normal methods with the slightest error having to be eliminated. Many factors had to be considered for the river was narrow and the ship was long.
The problems of a launch of this size were enormous. Very early on in the proceedings, John Browns had to decide the width and slope of the slipway on which the liner would slide down to the water. The effects of temperature on the launch lubricant grease mixture had to be considered and a host of other factors had all to be checked, evaluated and re-checked.
John Starks, assistant managing director heading John Brown’s design team:
“The first step is, obviously, to make sure that it will move. When it starts to move the first things that starts to happen is that the stern begins to lift. As it does so pressure on the forward end of the slipway is increased very considerably as it is taking the whole weight of the ship, apart from any buoyancy that the water is taking. One must, therefore, make sure that the ship is then strong enough to take the stress at the forward end.
“You also have to ensure by calculation that the ship will float off the slipway as opposed to dropping off and you also have to make sure that it is waterborne while it is reasonable clear of the slipway. The next thing that you have to decide is how far the ship can be expected to travel and you have to decide what drag chains you are going to attaché at what points to prevent the ship from going too far.
“What most people do not appreciate is that the ship takes a very rough ride during its launch. She bends during the course of the launch and we have to make sure that all her structure is absolutely sound. We, therefore, inspect the ship very carefully. She probably gets far more local stresses during the launch than she ever will during the course of her working life.
“The most critical factor by far in the launch is the depth of water available at the aft end of the slipways. The River Clyde is extremely tempremental; sometimes the water is deficient and sometimes is it excessive. If we have too much water, the danger is that the ship will really be afloat before she is clear at the end of the slipway and the danger is that, since high water is usually associated with high wind, if she is not clear at the end of the ways she could damage herself on one of the cranes. The problem usually solves itself because if the wind and water are that high, it is obviously no condition in which to launch a ship. This happens very infrequently and is obviously something to be avoided, but nevertheless the problem is still there.
“We, therefore, watch the weather forecasts very carefully before the day. We also measure the heights of the tides for a good many days before the launch to check whether the river is running true to form, under prediction or over prediction. We also measure the river in Greenock and Glasgow as a precaution and we are halfway between the two we can get a very good idea of what the river is doing. Having obtained this information we then can, within certain limits, ballast the ship to aim off for weather conditions, but obviously in a ship of this size the resources pen to us are limited”.
The man responsible for the slipway was Robert Craig, head foreman shipwright. He had worked at John Brown’s since he left school in 1918 and Q4 would be his 47th launch as head foreman. He built the slipway from the information given to him. Its declivity (downward inclination towards the river) was ½ inch to the foot. Every square foot of the sliding and standing (fixed) ways to bear a weight of more than two tons – he claimed for Q4 it was 2,089 tons.
He used 16,300 feet of 12” square timber to build the supporting poppets (cradles) at each end of the ship. Once the ship rested on 300 keel blocks but these had now been knocked away; the berth had been stripped of the huge shores like tress trunks, bilge blocks and wedges.
Q4 rested on two sliding ways, each formed of 25 lengths of timber 30 feet long, six feet wide and 12 inches thick. The sliding and standing ways had been greased with a concoction of nine tons of tallow compound, 70 gallons of sperm oil, 14 cwt. of soft black soap and seven gallons of fine spindle oil. Robert Craig took responsibility for this.
Q4 was held by six mighty triggers, each with its eight inch wooded tongue set into the sliding ways. Wires trailed from a tiny electrical device to the button on the high platform where the Queen would perform the launching ceremony. As the Queen pressed the button the powerful trigger arms would snap back in their pits with a report like an artillery salute. Then Q4 would glide towards the river; and just in case the liner is reluctant to leave the berth, two hydraulic rams would give her a nudge – a push with the power of 1,200 lbs per square inch behind it.
In the river six tugs would be waiting to handle the ship – three at the fore and three at the aft. Another will be standing by for any emergency. Lines would be rocketed from the tugs to the new Cunarder and towing lines would be secured and the new ship would move towards her fitting-out berth.
