Diving on IWSS

Wärtsilä Sternguard IWSS

Fully in-water serviceable seal

Wärtsilä Sternguard IWSS

The Wartsila Sternguard In-Water Serviceable Seal (IWSS) is a fully underwater serviceable seal. This provides segments including commercial, cruise & ferry, merchant and in-land waterway vessels with opportunities to reduce down-time as there is no requirements for dry-docking, habitat usage and shaft withdrawal.

This reduces costs as there is no requirement to drain the stern tube oil or aid and transfer vessels to a dry dock slot. In addition, there is no need to unload cargo for an underwater overhaul.

The Sternguard IWSS has been designed to provide a reliable and faster service as well as improved operational performance. Environmentally Acceptable Lubricants (EALs) and mineral oil lubricant are accepted and the seal is compliant with the 2013 US EPA Vessel General Permit rules.*

*when used with EALs


The Wärtsilä Sternguard IWSS can be used to retrofit any other seal type and is available for a wide range of segment areas including merchant, offshore and cruise & ferry vessels, running on mineral or bio oil (EAL’s).

The pressure springs ensure a continuous pressure between the lapped surfaces and enables axial movement of the static section. A sealing device exists inside the static section, which prevents lubricant leakage during axial movement.
underwater services
Sternguard In Water Serviceable Seal-661px
Using qualified divers that are fully trained to service the seal under water, we provide global coverage and easy-to-ship diving support that allows us to be present anywhere in the world, when needed.
To enhance serviceability, the seal is equipped with an inflatable seal which eliminates the need for draining the whole stern tube during overhaul. In addition, the inflatable seal minimises the possibility of leakage of lubricant to the environment during in water service.
This seal is available partially split for installations with shaft removals in dry dock, but also fully split for in-water overhauls or dry dock installations. 


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