Using the S-lay installation method, pipe joints are welded together onboard the vessel in a horizontal production line. The seagoing pipe is supported by a stinger to control the radius when the pipe bends towards the seabed. The stinger is generally installed at the stern of the vessel and can be an arc over 120m long to keep the bending stress within limits.
Due to the high production rate and the possibility to install concrete coated pipe, S-lay is extremely suitable for pipe installation in shallow and intermediate waters. Greater water depths are also possible, but require a relatively long stinger and a large vessel to support it.
An example of a Huisman designed and delivered S-lay system can be found onboard the Seven Borealis. This vessel combines a 600mt S-lay system with a J-lay tower for pipelaying purposes and a 5,000mt Offshore Mast Crane for heavy lifting and deep water construction.