9th December 1903 Cleethorpes
Cleethorpes had arrived on the Humber from her builders in Dundee on 21st November and had spent the next couple of weeks lying alongside at New Holland whilst receiving the finishing touches to make her ready for service.
By the week commencing Monday 7th December all was set so the boiler was lit to start the process of raising steam. With these sorts of traditional boilers this is best done over about three days from cold so that the boiler is heated up gently and so is not subjected to violent stresses and strains.
On the first day a warming fire would have been lit in just one furnace. As the heat started to percolate through the boiler the warmer water would have started to rise displacing cold water which would have fallen thereby setting up natural convection currents circulating within the boiler. By the end of that first day the top of the boiler would have been hot to the touch but the bottom would still have been stone cold.
On the second a day a more vigorous fire would have been lit encouraging the convection currents of water within the boiler to circulate more speedily. By the end of that day the whole boiler would have been very hot to the touch top and bottom and starting to make a little bit of steam at the top.
Then on the third day steam would have been raised. It is a long old process but it is best done this way. To start making steam when the top of the boiler is hot and the bottom still cold introduces unwelcome stresses and strains in a boiler structure which do it no good at all.
So with steam up Cleethorpes sailed away from New Holland Pier for trials in the river on Wednesday 9th December 1903.