STC Trade, Better than steel

It doesn’t corrode, it is lighter and more efficient. Arriving from Holland are polyethylene filters for all vessels, from 10 to 150 meters

by Niccolò Volpati

As hard as steel. It is a common saying, and stainless steel is definitely a material that is widely used aboard yachts. The belief is true that it is very resistant, including to corrosion. And it is no coincidence that filters are made in stainless steel. Any onboard tubing that needs to filter water has a kind of metal basket inside it. The smallest ones are the size of a cup, while larger ones are as big as to waste bins and the ones for cargo ships get to a meter and a half in height and half a meter in diameter. What is the problem? That, as is often said, a boat is a big floating filter. It filters seawater which, after being passed through the membrane of a desalination device, is used as drinking water. Water is used in the engine room to cool engines and other systems, and this also has to be filtered, and then there is bilge water. So basically, there is a lot of water on board, but it is also an excellent conductor and metal becomes exposed to galvanic corrosion, especially when a yacht is made with different alloys because they produce a sort of “battery” effect.

STC filters are made in HDPE (High-Density Polyethylene), a polymer that resists pressure, is a flame retardant and above all doesn’t corrode.

But now there is an alternative to metal filters that has arrived from Holland. These are high-density polyethylene filters made by STC. What advantages do they provide?  They don’t know the meaning of corrosion, and even if galvanic corrosion were present, they break the circuit and block it. They are also very much lighter, and in addition to the benefit that the weight reduction has on fuel consumption, maintenance is easier. The filters have to be cleaned and to do that you have to lift them out.


That is something that is normally done in the engine room, where there isn’t a lot of room, and – as you can easily imagine – if the filter is made of plastic, and thus lighter, it is easier to lift out and thus also to clean. We are used to thinking that there is nothing stronger than steel. STC’s patented polyethylene filters are IMO certified, crushproof, and guaranteed to stop the spread of fire. As the standards demand, they are subjected to lateral pressure without breaking or changing shape, exactly like steel.

Polyethylene is patented, and a filter made from it has the same capacity as one made in metal.

Aboard a mega yacht, even without particular corrosion problems, filters are changed at least once a year. With the right maintenance and cleaning, the polyethylene ones – by contrast – last a lot longer, and that means saving for boat owners. The cost of production is slightly higher, in part because they are custom made, but the benefits can be seen in how long they last, and how efficient they are. STC has been supplying Dutch yards that make new yachts for over ten years. But in the Mediterranean, it is more likely that they are requested during refitting work. What can happen is that, after having had a corrosion problem, people look for a solution and find it in these polyethylene filters. But isn’t prevention better than cure?

STC Trade
T. +31 6 51790638
[email protected]

Above, photo by Guillaume Plisson

(STC Trade, Better than steel – – June 2022)