Tin has a bearing on the environment

While there is nothing revolutionary in the world of stern tube bearings, Hiroshi Kokaji, sales manager for Japan Marine Technologies, part of Wärtsilä Propulsion, explains: “We have two types of white metal bearing ? one is a tin-based white metal and the other a lead-based white metal. Tin-based white metal is far superior to lead-based white metal which, along with it being more environmentally friendly, is why owners are opting for the tin-based option.

When it comes to bushes, the company also has two options ? ductile iron and cast iron, with many shipyards now requesting the harder ductile iron.

“In this day and age one has to offer the customer environmentally friendly seals, and non-polluting and anti-pollution are key terms we have been using over the past few years,” says Colin Hyde, sales director for Wärtsilä Propulsion (Seals and Bearings).

Wärtsilä Propulsion currently produces two brands of seals. Coastguard is a truly anti-pollutant seal. “Any pollutants can be brought back inside the ship because of an encapsulated system within the seal itself,” Hyde explains. The other one, produced in Japan, is called AirGuard and is an air-induced seal. “This promotes air to the back end and by design we can ensure that any pollutants are again run back into the ship,” says Hyde.

He adds that the seals used to be fitted mainly to cruise ships but that has all changed. “It?s virtually any ship that floats now, with so many horrendous fines and impoundings happening in places such as the US and Japan. The spotter planes are after people who are cleaning bilges out but if your stern tube is leaking that will give you as much of an oil sheen on the water as anything else.”

The trend has changed in that all ships entering ports of some note around the world are very conscious of leaking sterntube seals so the company is seeing a definite change in customer awareness. He told The Motor Ship “Even the operators are now becoming responsible, which is good. If you go back 10 years a lot of people really didn?t care.” n