From flat steel to ship, growth in a shipyard.

By Robert Haynes

I’m Robert, and I’m a naval architect. It’s a bit of an unusual job, but I think it’s a really great one - I design ships and oversee their construction. I did a degree in Naval Architecture at the University of Strathclyde before starting work back in 2011. Since then I’ve worked on everything from tugboats to aircraft carriers!

The theme of Science Week this year is growth; while that might make you think of something like a forest – and there’s nothing wrong with that, forests are awesome – you can think of anything that’s built out of smaller parts as growing. Ships are some of the biggest moving objects that humans create; imagine a tower block turned on its side, and you’re not far off!

Most ships are built out of steel, which comes in two kinds. There are steel plates, which are the big flat bits that actually make up the hull, decks (floors) and bulkheads (walls). There are also steel sections, which are long, thin bits of metal used to stiffen the plates.

At a shipyard, all the steel is delivered ahead of time and kept in a steel stockyard until it’s needed. This means that the shipyard can get the best price by ordering in bulk, and if there’s a delay to a delivery work can carry on. The steel can now be cut and bent into the right shapes for the ship by computer-controlled machines. For the most difficult shapes, they have to be made out of lots of smaller shapes bent individually – similar to how a football is made from hexagons and pentagons.

Once the steel has been prepared, the shipyard basically has a flat-pack ship. The first step in putting the ship together is carried out in an area known as the ‘prefabrication shop’. to take a plate, and weld the stiffening sections to it. This is always done with the plate on the bottom, because this is the easiest position for welding. This creates simple units known as panels or sub-assemblies.

At this stage the shipyard can start adding pipes and other equipment. Putting these in at an early stage is best, because the workers can easily carry them in at ground level without having to go up and down ladders. Larger bits of equipment, like engines, can’t be installed until the ship is more complete, but as early as possible is best.

Ship units being completed in the assembly hall at Portsmouth dockyard. Source:

If you’ve ever been lucky enough to build a large LEGO set, the rest of the process will be familiar; small sections of the finished object are brought together, making bigger and bigger parts at each step.

In the shipyard, sub-assemblies are welded together in an assembly hall to make units, which are usually the size of a small building, typically weighing a few hundred to a thousand tonnes. These are joined together to make blocks, which are basically slices of ship – sometimes as big as thirty or forty metres on a side and weighing thousands of tonnes.

These blocks are rolled out on huge self-propelled transporters into the final assembly area, which might be a dry dock or concrete platform, where they can be joined together. Once everything is ready and the ship has been made watertight, it can finally be launched. It may take several years for a ship to grow, in stages, from simple materials to a finished item.